I-P_A19_Ch09.fm

9.1

CHAPTER 9

HEALTH CARE FACILITIES

REGULATION AND RESOURCES........................................... 9.1

Air Conditioning in Disease Prevention and Treatment ........... 9.2

Sustainability ............................................................................. 9.3

HOSPITAL FACILITIES............................................................ 9.3

Air Quality ................................................................................. 9.3

Facility Design and Operation .................................................. 9.6

Specific Design Criteria............................................................. 9.7

OUTPATIENT HEALTH CARE FACILITIES ......................... 9.16

Dental Care Facilities.............................................................. 9.17

Continuity of Service and Energy Concepts............................. 9.17

RESIDENTIAL HEALTH, CARE, AND

SUPPORT FACILITIES ....................................................... 9.17

ONTINUAL advances in medicine and technology necessitate

Cconstant reevaluation of the air-conditioning needs of hospitals

and medical facilities. Medical evidence shows that air conditioning

can affect certain clinical outcomes, and ventilation requirements

exist to protect against harmful occupational exposures. Although

the need for clean and conditioned air in health care facilities is high,

the relatively high cost of air conditioning demands efficient design

and operation to ensure economical energy management. It is a chal-

lenge to establish a balance between patient outcomes, safety, and

higher operating costs. Often, there is little research or data to quan-

tify the effect of the HVAC system on patient outcomes; whereas

energy costs are relatively easy to quantify. The following is a sug-

gested prioritization of the HVAC system design characteristics for

a healthcare facility (Turpin 2013):

1. Performance (infection control, comfort, patient outcome)

2. Safety (fire, life safety, potential injuries)

3. Reliability

4. Maintenance cost

5. Energy cost

6. Adaptability

Health care occupancy classification, based on the latest occu-

pancy guidelines from the National Fire Protection Association’s

(NFPA) Life Safety Code

and applicable building codes, should be

considered early in project design. Health care facilities are unique

in that there may be multiple, differing authorities having jurisdic-

tion (AHJs) overseeing the design, construction, and operation of the

facility. These different AHJs may use different standards or differ-

ent versions of the same standards. Health care occupancy classifi-

cation is important to determine for fire protection (smoke zones,

smoke control) and for future adaptability of the HVAC system for a

more restrictive occupancy.

Health care facilities are increasingly diversifying in response to

a trend toward outpatient services. The term clinic may refer to any

building from a residential doctor’s office to a specialized cancer

treatment center. Integrated regional health care organizations are

becoming the model for medical care delivery as outpatient facilities

take on more advanced care and increasingly serve as the entry-

way to the acute care hospital. These organizations, as well as long-

established hospitals, are sometimes constructing buildings that look

less like hospitals and more like luxury hotels and office buildings.

However, when specific health care treatments in these facilities are

medically consistent with hospital-based treatment activity, then

the environmental design guidance applicable to the hospital-based

treatment should also apply to the clinic’s treatment environment.

For the purpose of this chapter, health care facilities are divided

into the following categories:

• Hospital facilities

• Outpatient health care facilities

• Residential health care and support facilities

The general hospital provides a variety of services; its environ-

mental conditions and design criteria apply to comparable areas in

other health care facilities. The general acute care hospital has a core

of patient care spaces, including rooms for operations, emergency

treatment, delivery, patients, and a nursery. Usually, the functions of

radiology, laboratory, central sterile, and pharmacy are located close

to the critical care space. Inpatient nursing, including intensive care

nursing, is also within the complex. The facility also incorporates a

kitchen, dining and food service, morgue, and central housekeeping

support.

Outpatient surgery is performed with the anticipation that the

patient will not stay overnight. An outpatient facility may be part of

an acute care facility, a freestanding unit, or part of another medical

facility such as a medical office building.

Nursing facilities are addressed separately, because their funda-

mental requirements differ greatly from those of other medical facil-

ities in regards to odor control and the average stay of patients.

Dental facilities are briefly discussed. Requirements for these

facilities differ from those of other health care facilities because

many procedures generate aerosols, dusts, and particulates.

1. REGULATION AND

RESOURCES

The specific environmental conditions required by a particular

medical facility may vary from those in this chapter, depending on the

agency responsible for the environmental standard. ANSI/ASHRAE/

ASHE Standard 170 represents the minimum design standard for

these facilities, and gives specific minimum requirements for space

design temperatures and humidities as well as ventilation recommen-

dations for comfort, asepsis, and odor control in spaces that directly

affect patient care.

Standard 170 is in continuous maintenance by ASHRAE, with

proposed addenda available for public review/comment and pub-

lished addenda available for free download from www.ashrae.org. It

is republished in whole approximately every four years with all pub-

lished addenda incorporated. See Table 1 for an excerpt of require-

ments found in ASHRAE Standard 170.

Standard 170 is also included in its entirety in the Facility Guide-

lines Institute’s Guidelines for Design and Construction of Hospitals

and Outpatient Facilities and Guidelines for Design and Construc-

tion of Residential Health, Care, and Support Facilities (FGI 2014a,

2014b). The FGI Guidelines are adopted in more than 42 U.S. states

by AHJs overseeing the planning, construction, and operation of

health care facilities in those states.

Many outpatient facilities are B-occupancy, and may require

compliance to ASHRAE/ANSI Standard 90.1 or other energy regu-

lations, which may also cover ventilation. ASHRAE Guidelines 10

The preparation of this chapter is assigned to TC 9.6, Healthcare Facilities.

9.2 2019 ASHRAE Handbook—HVAC Applications

and 29 may be especially applicable to the design of health care

facilities. The HVAC Design Manual for Hospitals and Clinics

(ASHRAE 2013) presents enhanced design practice approaches to

health care facility design and greatly supplements the information

in this chapter. The ASHRAE Learning Institute (ALI) provides

many applicable courses, including Designing High Performing

Health Care HVAC Systems and Health Care Facilities: Best Prac-

tice Design and Applications.

ASHRAE Standard 188-2015 requires health care buildings to

establish a water management program to control growth of Legio-

nella. The program must include a systematic analysis of building

water systems, including the locations of end-point uses of potable

and nonpotable water systems; the location of water processing

equipment and components, and how water is received and pro-

cessed, including how it is conditioned, stored, heated, cooled, re-

circulated, and delivered to end-point uses. A process flow diagram

is required to graphically describe the step-by-step detail of where

building water systems are at risk of harboring or promoting Legio-

nella growth and dissemination. Those areas so identified must have

control measures and limits established to allow monitoring of con-

ditions and corrective actions to ensure the system is operating as

designed.

NFPA Standard 99, which has been adopted by many jurisdic-

tions, provides requirements for ventilation of medical gas storage

and transfilling spaces. It also has requirements for heating, cooling,

and ventilating the emergency power system room.

American Society for Healthcare Engineering’s (ASHE) mono-

graphs and interpretation tools are an important resource to help

integrate facility management considerations into the built environ-

ment. The American Conference of Governmental Industrial

Hygienists’ (ACGIH 2013) Industrial Ventilation: A Manual of Rec-

ommended Practice for Design includes guidance on source control

of contaminants.

Agencies that may have standards and guidelines applicable to

medical facilities include state and local health agencies, the U.S.

Department of Health and Human Services (including the Centers

for Disease Control and Prevention [CDC], Indian Health Service,

Food and Drug Administration [FDA], U.S. Public Health Service,

and Medicare/Medicaid), U.S. Department of Defense, U.S.

Department of Veterans Affairs, and The Joint Commission’s Hos-

pital Accreditation Program.

Other medically concerned organizations with design and/or

operational standards and guidelines that may be applicable to health

care facility design include the United States Pharmacopeia (USP),

American Association of Operating Room Nurses (AAORN), and

Association for the Advancement of Medical Instrumentation

(AAMI).

FGI (2014a, 2014b) requires the owner to provide an infection

control risk assessment (ICRA) and prepare infection control risk

mitigation recommendations (ICRMR) that are intended to pre-

identify and control infection risks arising from facility construction

activities. The ICRMR and ICRA are then to be incorporated in the

contract documents by the design professional. Therefore, it is essen-

tial to discuss infection control objectives with the hospital’s infec-

tion control committee.

International standards for health care ventilation sometimes con-

tain suggestions that differ significantly from those in this chapter.

International standards include the following:

• Canada’s CSA Group’s Standard Z317.2

• Australasian Health Facility Guidelines (AusHFG), available at

www.healthfacilityguidelines.com.au

• U.K. Department of Health and Social Care’s Healthcare Techni-

cal Memorandum 03-01 premises

• German Institute for Standardization’s (DIN) Standard 1946-4

Ventilation and air conditioning—Part 4

• Spain’s AENOR/UNE Standard 100713:2005

• Department of Health–Abu Dhabi (HAAD) Health Facility Guide-

lines, available at www.healthdesign.com.au/haad.hfg/

•World Health Organization’s (WHO) Natural Ventilation for In-

fection Control in Health-Care Settings

ASHRAE international associate societies (e.g., India’s ISHRAE)

may have health care resources specific to the local culture and cli-

mate; see www.ashraeasa.org/members.html for a list of associate

organizations.

Along with HVAC requirements for normal operation, many

health care facilities are considered essential facilities and have pro-

grammatic requirements to remain operational after earthquakes or

other naturally occurring events. Building code importance factor

designation and application can require structural and restraint fea-

tures not normally included in other types of facilities. Many health

care facilities have on-site diesel engine generated electric power,

which can necessitate EPA fuel storage permitting, security require-

ments, and potentially air permitting issues.

1.1 AIR CONDITIONING IN DISEASE

PREVENTION AND TREATMENT

In hospitals, air conditioning can play a role beyond the promo-

tion of comfort. In many cases, proper air conditioning is a factor in

patient therapy. Patients in well-controlled environments generally

show more rapid physical improvement than those in poorly con-

trolled environments. Examples of HVAC considerations for vari-

ous patients include the following:

• Patients exhibiting thyrotoxicosis (related to hyperthyroidism) may

be more sensitive to hot, humid conditions or heat waves (Pearce

2006).

• Extreme ambient heat is a public health threat, especially for the

elderly and persons with preexisting health conditions (Richard et

al. 2011).

• Cardiac patients are often unable to maintain the circulation nec-

essary to ensure normal heat loss. Air conditioning cardiac wards

and rooms of cardiac patients, particularly those with congestive

heart failure, is necessary and considered therapeutic (Burch and

Pasquale1962).

• Individuals subjected to operations and those with barbiturate

poisoning may be susceptible to hypothermia (Belani et al. 2013).

HVAC systems may reduce this risk.

Table 1 Sample of ASHRAE Standard 170 Design Parameters

Function of Space

Pressure

Relationship to

Adjacent Areas

Minimum

Outdoor

ach*

Minimum

Total

ach*

All Room Air

Exhausted Directly

to Outdoors

Air Recirculated

by Room Units

Design

Relative

Humidity,%

Design

Temp.

°F

Operating room Positive 4 20 NR* No 20 to 60 68 to 75

Emergency department public waiting area Negative 2 12 Yes NR* max. 65 70 to 75

AII rooms Negative 2 12 Yes No max. 60 70 to 75

Patient room NR* 2 4 NR* NR* max. 60 70 to 75

*ach = air changes per hour, NR = no requirement.

Health Care Facilities 9.3

• Symptoms of rheumatoid arthritis are correlated to humidity of

the environment (Patberg and Rasker 2004). Some have suggest-

ed the benefit of dry environments (less than 35% rh).

• Dry air increases the difficulty in terminally cleaning spaces and

causes particles to remain airborne for longer periods of time.

Pathogen transmission through the air is greater when the air is

dry, and infectious particles travel deeper into the lungs when they

are small. Cilia in the respiratory system, which are responsible

for clearing particulates out of the bronchial tubes, have reduced

function in dry conditions. Dry air also leads to cracks in the skin

and increased cortisol production.

• Clinical areas devoted to upper respiratory disease treatment and

acute care are often maintained at a minimum of 30% rh. The

foundation and associated clinical benefit of this practice have re-

cently come under question, so the designer is encouraged to

closely consult the latest design guidance and the facility owner

when establishing this design criterion.

• Exposure to dry environments may have a negative impact. Taylor

(2016) found an increase in the number of healthcare associated

infections in patients in a medical-surgery wing and in an oncol-

ogy wing when the relative humidity dropped below 40% rh.

• Patients with chronic pulmonary disease often have viscous respi-

ratory tract secretions. As these secretions accumulate and in-

crease in viscosity, the patient’s exchange of heat and water

dwindles. Under these circumstances, inspiration of warm, hu-

midified air is essential to prevent dehydration (Walker and Wells

1961).

• Patients needing oxygen therapy, those with tracheotomies, and

other mechanically ventilated patients require warm, humidified

air (Jackson 1996). Cold, dry oxygen or bypassing the nasopharyn-

geal mucosa presents an extreme situation. Rebreathing techniques

for anesthesia and enclosure in an incubator are special means of

addressing impaired heat loss in therapeutic environments.

• Warm, moist air has been shown to be beneficial in treatment of

burn patients (Liljedahl et al. 1979; Zhou et al. 1998). A ward for

severe burn victims should have temperature controls (and com-

patible architectural design and construction) that allow room tem-

peratures up to 90°F db and relative humidity up to 95%.

Reducing hospital-acquired infections (HAIs; also called nos-

ocomial infections) is a focus of the health care industry. It is diffi-

cult to draw any general conclusions about HVAC’s contributions or

ability to affect infections (DeRoos et al. 1978; Jacob et al. 2013).

True airborne infection is somewhat rare (5 to 15%), compared to the

direct route of infection (Short and Al-Maiyah 2009),although there

is evidence that too little ventilation increases risk of infection (At-

kinson 2009). The exact ventilation rates needed to control infectious

agents in hospitals are not known (Li et al. 2007; Memarzadeh

2013). It was previously believed that 100% exhaust or 100% out-

door air was necessary. ASHRAE research project RP-312 found

that recirculation of most hospital air is appropriate (Chaddock 1983).

HVAC engineering controls, such as required differential pressure

relationships between spaces, directional airflow, methods of air

delivery, air filtration, overall building pressurization, etc., directly

contribute to maintaining asepsis. Well-designed HVAC systems

also affect indoor environmental quality and asepsis integrity

through specifically HVAC related factors (e.g., thermal comfort,

acoustics, odor control). Therefore, HVAC system effectiveness

can also lead to an improved healing environment for the patient,

contributing to shorter patient stays and thereby minimizing the

risk of HAIs. ASHE (2011) provides an engineering perspective on

the topic with many additional references.

1.2 SUSTAINABILITY

Health care is an energy intensive, energy-dependent enterprise.

Hospital facilities are different from other structures in that they

operate 24 hours a day and year round, require sophisticated back up

systems in case of utility shutdowns, use large quantities of outdoor

air to combat odors and to dilute microorganisms, and must deal with

problems of infection and solid waste disposal. Similarly, large quan-

tities of energy are required to power diagnostic, therapeutic, and

monitoring equipment, and to support services such as food storage,

preparation, and service and laundry facilities. Control strategies

such as supply air temperature reset on variable-air-volume systems

and hydronic reheat supply water temperature reset on variable

pumping systems can often be applied with good results, but should

be applied with care: undesired impacts on temperature and (espe-

cially) humidity can result. Resources to help ensure efficient, eco-

nomical energy management and reduce energy consumption in

hospital facilities include ASHRAE Standard 90.1 and the Advanced

Energy Design Guides on hospitals (ASHRAE 2009, 2012). ASH-

RAE Standard 189.3 provides guidance for design, construction, and

operation of high-performance, green health care facilities.

Hospitals can conserve energy in various ways, such as using in-

dividual zoning control with advanced control strategies and energy

conversion devices that transfer energy from building exhaust air to

incoming outdoor air. The critical nature of the health care environ-

ment requires design and operational precautions to minimize the

chances of heat exchangers becoming a source of contaminants in

the supply air stream. Use of heat pipes, runaround loops, enthalpy

wheels, and other forms of heat recovery is increasing; ASHRAE

Standard 170 addresses their use. Large health care campuses use

central plant systems, which may include thermal storage, hydronic

economizers, primary/secondary pumping, cogeneration, heat re-

covery boilers, and heat recovery incinerators. Integrating building

waste heat into systems and using renewable energy sources (e.g.,

solar under some climatic conditions) provide substantial savings

(Setty 1976).

Selecting building and system components for cost effective

energy measures requires careful planning and design. Life-cycle

cost analysis can show the full effect of design decisions, considering

fuel and labor costs, maintenance costs, desired performance (com-

fort and air quality), replacement costs, cost of downtime, and the

value of investment dollars over time.

2. HOSPITAL FACILITIES

Although proper air conditioning is helpful in preventing and

treating disease, application of air conditioning to health care facil-

ities presents many problems not encountered in usual comfort con-

ditioning design.

The basic differences between air conditioning for hospitals (and

related health care facilities) and that for other building types stem

from the (1) need to restrict air movement in and between depart-

ments; (2) specific requirements for ventilation and filtration to

dilute and remove contamination (odor, airborne microorganisms

and viruses, hazardous chemicals, and radioactive substances); (3)

different temperature and humidity requirements for various areas;

and (4) design sophistication needed for accurate control of environ-

mental conditions.

2.1 AIR QUALITY

Systems should provide air virtually free of dust, dirt, odor, and

chemical and radioactive pollutants. In some cases, untreated out-

door air is hazardous to patients suffering from cardiopulmonary,

respiratory, or pulmonary conditions. In such instances, consider

treatment of outdoor air as discussed in ASHRAE Standard 62.1.

Infection Sources

Bacterial Infection. Mycobacterium tuberculosis and Legio-

nella pneumophila (Legionnaires’ disease) are examples of bacteria

that are highly infectious and transported in air (or air and water

9.4 2019 ASHRAE Handbook—HVAC Applications

mixtures). Wells (1934) showed that droplets or infectious agents of

5 m or less in size can remain airborne indefinitely.

Viral Infection. Examples of viruses that are transported by, and

virulent within, air are Varicella (chicken pox/shingles), Rubella

(German measles), and Rubeola (regular measles). Research indi-

cates that many airborne viruses that transmit infection are origi-

nally submicron in size, though in air they are often attached to

larger aerosol and/or as conglomerates of multiple viruses, which

may be more easily filtered from the airstream.

Molds. Evidence indicates that some molds such as Aspergillis

can be fatal to advanced leukemia, bone marrow transplant, and

other immunocompromised patients.

Chemicals. Hospitals use various chemicals as disinfectants,

which may require control measures for worker or patient safety.

Many pharmaceuticals are powerful chemical agents.

Control Measures

Outdoor Air Ventilation. If outdoor air intakes are properly

located and areas adjacent to the intakes are properly maintained,

outdoor air is virtually free of infectious bacteria and viruses com-

pared to room air. Infection control problems frequently involve a

bacterial or viral source within the hospital. Ventilation air dilutes

indoor viral and bacterial contamination. If ventilation systems are

properly designed, constructed, and maintained to preserve cor-

rect pressure relations between functional areas, they control the

between-area spread of airborne infectious agents and enable proper

containment and removal of pathogens from the hospital environ-

ment.

Filtration. Some authorities recommend using high-efficiency

particulate air (HEPA) filters with test filtering efficiencies of

99.97% in certain areas. Although there is no known method to ef-

fectively eliminate 100% of the viable particles, HEPA and/or

ultralow-penetration (ULPA) filters provide the greatest air-cleaning

efficiency currently available.

Pressure Differential. Directional airflow created by differen-

tial pressures, which result from controlling the HVAC system in a

particular manner, is a common control measure to help prevent dis-

persal of contaminants between adjoining spaces.

Anterooms. Isolation rooms and isolation anterooms with ap-

propriate ventilation/pressure relationships are a primary means

used to prevent the spread of airborne contaminants from space to

space in the health care environment. The addition of the anteroom

allows for the dilution and control of air that passes from one space

to another every time a door is opened and closed.

Contaminant Source Control. Certain aerosol-generating ac-

tivities may also benefit from local control techniques to minimize

virus dissemination and other contaminants. Exhausted enclosures

(e.g., biological safety cabinets, chemical fume hoods, benchtop

enclosures) and localized collection methods (e.g., snorkels, direct

equipment connections) are typical control measures. Physical lo-

cations of supply air diffusers and return/exhaust grilles in a space

can be designed to help control contaminant dispersal within the

room.

Temperature and Humidity. These conditions can inhibit or

promote the growth of bacteria, and activate or deactivate viruses.

Some bacteria, such as Legionella pneumophila, are basically wa-

terborne and survive more readily in a humid environment. Codes

and guidelines specify temperature and humidity range criteria in

some hospital areas for infection control as well as comfort. His-

torical use of flammable anesthetics also influenced the minimum

relative humidity requirements of various governing documents.

Where flammable anesthetics have been phased out, there is con-

siderable interest in lowering minimum humidity requirements

because of the humidification systems’ increased energy usage

and operational and maintenance challenges. Medical equipment

static electricity concerns and transmission and growth of various

potential contaminants in differing humidity environments have

also been examined, and led to a relaxation of some minimum rel-

ative humidity requirements in ASHRAE Standard

170. Special-

ized patient care areas, including organ transplant and burn units,

should have additional ventilation provisions for air quality control

as may be appropriate.

Ultraviolet Light, Ionization and Chemicals. ASHRAE guid-

ance on the use of ultraviolet energy as an adjunct infection control

measure may be found in Chapter 60 of the 2015 ASHRAE Hand-

book—HVAC Applications and Chapter 17 of the 2016 ASHRAE

Handbook—HVAC Systems and Equipment. Current guidance from

the U.S. Centers for Disease Control and Prevention can be found in

CDC (2005) and NIOSH (2009). Ionization devices and/or chemical

fogging/mists are not recommended in occupied environments and

should only be considered for terminal cleaning applications in un-

occupied spaces.

Increasing Air Changes. Whether achieved by introducing

clean fresh air or filtration, increasing a room’s air change rate re-

duces its airborne burden of microorganisms, thus reducing oppor-

tunities for airborne exposures. Table 2 notes the theoretical time to

remove particles from a room being flushed with clean, filtered air,

assuming perfect mixing/perfect ventilation effectiveness in the

space (ASHRAE 2013).

Outdoor Air Intakes. These intakes should be located as far as

is practical (on directionally different [i.e., compass directions]

exposures whenever possible), but not less than 25 ft, from combus-

tion equipment stack exhaust outlets, ventilation exhaust outlets

from the hospital or adjoining buildings, medical/surgical vacuum

systems, cooling towers, plumbing vent stacks, smoke control

exhaust outlets, and areas that may collect vehicular exhaust and

other noxious fumes. Air intakes should be located at least 30 ft

from any Class 4 air exhaust discharges as defined in Standard 62.1-

2010. The bottom of outdoor air intakes serving central systems

should be located as high as practical (minimum of 12 ft recom-

mended) but not less than 6 ft above ground level or, if installed

above the roof, 3 ft above the roof level.

Exhaust Air Outlets. These exhausts should be located a min-

imum of 10 ft above ground level and away from doors, occupied

areas, and operable windows. Preferred location for exhaust out-

lets is at roof level projecting upward or horizontally away from

outdoor air intakes. Care must be taken in locating highly con-

taminated exhausts (e.g., from engines, fume hoods, biological

safety cabinets, kitchen hoods, paint booths). Prevailing winds,

adjacent buildings, and discharge velocities must be taken into

account (see Chapter 24 of the 2017 ASHRAE Handbook—Funda-

mentals). In critical or complicated applications, wind tunnel studies

or computer modeling may be appropriate. ASHRAE Standard 170

contains additional minimum requirements for certain exhaust dis-

charges.

Air Filters. The purpose of filters is to remove contaminants

from the air. While there is no generally accepted ratio of organic to

Table 2 Effect of Air Change Rates on Particle Removal

Air Changes

per Hour, ach

Time Required for Removal

Efficiency of 99%, min

Time Required for Removal

Efficiency of 99.9%, min

2 138 207

469 104

646 69

835 52

10 28 41

12 23 35

15 18 28

20 14 21

50 6 8

Source: CDC (2003).

Health Care Facilities 9.5

inorganic particles, it is generally accepted that the presence of more

airborne particles correlates to a greater number of airborne micro-

organisms that cause surgical site infections (Birgand et al. 2015).

As with most HVAC design considerations, the engineer must guide

the owner to make the best choice of filters, considering life cycle

cost and efficacy for each air handler and space.

As described in 2017 ASHRAE Handbook—Fundamentals Chap-

ter 11, air contaminants are generally classified as

• Particles: These may be aerosols or particulate matter. Particles

may be organic, inorganic, viable, or non-viable. Particles of

interest are often 0.1 to 10 m.

• Gases: These include gases and vapors considered at the molecu-

lar level. Chapters 10 and 12 in the 2017 ASHRAE Handbook—

Fundamentals discuss techniques to manage odors.

HVAC filters, which may include prefilters, second-stage filters,

and final-stage filters, should be tested in accordance with ASH-

RAE Standard 52.2. This standard is written for testing filters un-

der controlled conditions (laboratory environment) and establishes

the minimum efficiency reporting value (MERV) of an air filter.

Filters are classified as MERV 1 to 16. Tests are based on removal

efficiency (%) in three particle size ranges: 0.3 to 1 m, 1 to 3 m,

and 3 to 10 m. The higher the MERV rating, the better the overall

removal. ASHRAE Standard 145.2 is written for testing gaseous

air contaminant filters under controlled conditions (laboratory en-

vironment) and establishes efficiency ratings for contaminants that

represent broad classes of organic chemicals and ozone.

Air filters necessitate a comprehensive management program,

including installation, monitoring, replacement, and disposal. Typ-

ically, the priorities for selecting an air filter are

1. Contaminant removal efficiency (MERV, MERV-A)

2. Initial and operating cost (Total cost of ownership)

3. Structural integrity

Some filters exhibit different behavior under field conditions. ISO

Standard 29462 describes testing of HVAC filters for removal effi-

ciency in field conditions. See Chapter 29 of the 2016 ASHRAE

Handbook—HVAC Systems and Equipment. All central ventilation

or air-conditioning systems should be equipped with filters having

efficiencies no lower than those indicated in ASHRAE Standard

170. Appropriate precautions should be observed to prevent wetting

the filter media by uncontrolled condensation or free moisture from

humidifiers. The filter system should be designed and equipped to

allow safe removal, disposal, and replacement of contaminated

filters.

Guidelines for filter installations are as follows:

• HEPA filters are required by Standard 170 only for protective-en-

vironment rooms. These rooms are used for patients with a high

susceptibility to infection due to leukemia, burns, bone marrow

transplant, chemotherapy, organ transplant, or human immunode-

ficiency virus (HIV). HEPA filters should also be considered for

discharge air from fume hoods or biological safety cabinets in

which infectious, highly toxic, or radioactive materials are pro-

cessed. Some hospitals choose to use HEPA filters on exhaust

originating from airborne infectious isolation rooms and on sup-

ply air to very sensitive patients, such as those in orthopedic sur-

gery. Filter seals or gaskets should be installed to prevent leakage

between filter segments and between the filter bed and its support-

ing frame. A small leak that allows any contaminated air to escape

through the filter significantly reduces performance. Leakage can

occur due to poor gaskets, warping of the rack, or holes in the

rack. Ensure that the rack is designed to withstand high lateral

pressure. Diagonal supports may be necessary to maintain the

integrity of the filter rack. Maintaining the rated filtration effi-

ciency over the entire installed service life of the filter should be

considered, particularly if the initial removal efficiency is based

on an electrostatic charge on the filter.

• High-efficiency filters should be installed in the system, with ade-

quate facilities provided for maintenance and in situ performance

testing without introducing contamination into the delivery

system or the area served. Also keep in mind maintenance work-

ers’ safety. High-efficiency filters are expensive. Energy costs

associated with the pressure drop can be 70% of the total cost of

ownership. Consider filter life, first cost, energy cost, and main-

tenance (installation, removal, and disposal). Provide a local

manometer to measure pressure drop across each filter bank. Be

sure the gauge range is appropriate (usually 0 to 2 in. of water).

Mark the gage with the manufacture’s recommended initial and

final pressure drops. In addition, BAS control sequences to

monitor and alarm, including ability to normalize or benchmark

pressure drops and associated airflows, indicate when replace-

ment is necessary even when air handlers operate at less than full

flow. Filter system life-cycle costs can be calculated and various

scenarios compared for overall optimization (Eurovent/CECO-

MAF 2005). Installing a lower-efficiency prefilter upstream of the

high-efficiency filter keeps coils cleaner and extend the life of the

high-efficiency final filter.

• During construction, openings in ductwork and diffusers should

be sealed in accordance with ASHRAE Standard 170 to prevent

intrusion of dust, dirt, and hazardous materials. Such contamina-

tion is often permanent and provides a medium for growth of

infectious agents. Existing or new filters as well as coils may rap-

idly become contaminated by construction dust. The final filter

should be installed downstream of all the chilled-water coil.

Air Movement

Table 3 illustrates the degree to which contamination can be

dispersed into the air by routine patient care activities. The bacte-

rial counts in the hallway clearly indicate the spread of this con-

tamination.

Because of the bacteria dispersal from such necessary activities,

air-handling systems should provide air movement patterns that

minimize spread of contamination. Undesirable airflow between

rooms and floors is often difficult to control because of open doors,

movement of staff and patients, temperature differentials, and stack

effect, which is accentuated by vertical openings such as chutes, ele-

vator shafts, stairwells, and mechanical shafts. Although some of

these factors are beyond practical control, the effect of others may

be minimized by terminating shaft openings in enclosed rooms and

by designing and balancing air systems to create positive or negative

air pressure in certain rooms and areas.

Pressure differential causes air to flow in or out of a room through

various leakage areas (e.g., perimeter of doors and windows, utility/

fixture penetrations, cracks). A level of differential air pressure

(0.01 in. of water) can be efficiently maintained only in a tightly

sealed room. Therefore, it is important to obtain a reasonably close

Table 3 Influence of Bedmaking on Airborne

Bacterial Count in Hospitals

Item

Count per Cubic Foot

Inside Patient

Room

Hallway near

Patient Room

Background 34 30

During bedmaking 140 64

10 min after 60 40

30 min after 36 27

Background 16

Normal bedmaking 100

Vigorous bedmaking 172

Source: Greene et al. (1960).

9.6 2019 ASHRAE Handbook—HVAC Applications

fit of all doors and seal all walls and floors, including penetrations

between pressurized areas. Opening a door between two areas imme-

diately reduces any existing pressure differential between them,

effectively nullifying the pressure difference. When such openings

occur, a natural interchange of air takes place between the two rooms

because of turbulence created by the door opening and closing and

personnel ingress/egress. For critical areas requiring both mainte-

nance of pressure differentials to adjacent spaces and personnel

movement between the critical and adjacent areas, consider using

anterooms. The purpose of differential pressurization is to inhibit

movement of potentially infectious particles from dirty areas to clean

ones. Figure 1 illustrates controlling airflow through pressurization.

More air is supplied to the cleanest areas, with less air supplied to

less clean areas, and air is exhausted from dirty areas.

In general, outlets supplying air to sensitive ultraclean areas

should be located on the ceiling, and several perimeter exhaust out-

lets should be near the floor. This arrangement provides downward

movement of clean air through the breathing and working zones to

the floor area for exhaust.

Airborne infectious isolation (AII) rooms should locate the ex-

haust outlets over the patient bed or on the wall behind the bed. Sup-

ply air may be located above and near the doorway and/or near the

exterior window with ceiling-mounted supply outlets. This arrange-

ment controls the flow of clean air first to parts of the room where

workers or visitors are likely to be, and then across the infected

source into the exhaust. Because of the relatively low air exchange

rates and minimal influence of the exhaust outlet, this arrangement’s

ability to achieve directional airflow is limited. The supply diffusers

must be carefully selected and located such that primary air throw

does not induce bedroom air to enter the corridor or anteroom (if

provided) or overly disturb the function of the exhaust to remove

contaminants (Memarzadeh and Xu 2011).

The laminar airflow concepts developed for industrial cleanroom

and pharmaceutical use have applications in surgical suites. There

are advocates of both vertical and horizontal laminar airflow sys-

tems, with and without fixed or movable walls around the surgical

team (Pfost 1981), as well as air curtain concepts. Vertical laminar

airflow in surgical operating rooms is predominantly unidirectional

where not obstructed by extensive quantities of ceiling-mounted

swing-arm booms.

Ventilation system design must, as much as possible, provide

air movement from clean to less clean areas. In critical-care areas,

use constant-volume systems to ensure proper pressure relation-

ships and ventilation. In noncritical patient care areas and staff

rooms, variable-air-volume (VAV) systems may be considered for

energy conservation; if VAV is used, take special care to ensure

that minimum ventilation rates as required by codes are main-

tained, and that pressure relationships between various spaces are

maintained. With VAV systems, a method such as air volume

tracking between supply, return, and exhaust could be used to con-

trol pressure relationships (Lewis 1988).

Smoke Control

As the ventilation design is developed, a proper smoke control

strategy must be considered. Both passive and active smoke control

systems are in use. Passive systems rely on fan shutdown, smoke

and fire barriers, and proper treatment of duct penetrations. Active

smoke control systems use the ventilation system to create areas of

positive and negative pressures that, along with fire and smoke par-

titions, limit the spread of smoke. The ventilation system may be

used in a smoke removal mode in which combustion products are

exhausted by mechanical means. NFPA Standard 99 has specific

guidance on smoke control and other safety provisions, which have

changed in each edition. The engineer and code authority should

carefully plan system operation and configuration with regards to

smoke control. Refer to Chapter 53 and NFPA Standards 90A, 92A,

and 101 as enforced by the AHJ.

2.2 FACILITY DESIGN AND OPERATION

Zoning

Zoning (using separate air systems for different departments)

may be indicated to (1) compensate for exposures caused by orien-

tation or for other conditions imposed by a particular building con-

figuration, (2) minimize recirculation between departments, (3)

provide flexibility of operation, (4) simplify provisions for opera-

tion on emergency power, and (5) conserve energy.

Ducting the air supply from several air-handling units into a

manifold gives central systems some standby capacity. When one

unit is shut down, air is diverted from noncritical or intermittently

operated areas to accommodate critical areas, which must operate

continuously. This, or another means of standby protection, is

essential if the air supply is not to be interrupted by routine mainte-

nance or component failure.

Separating supply, return, and exhaust systems by department is

often desirable, particularly for surgical, obstetrical, pathological,

and laboratory departments. The desired relative balance in critical

areas should be maintained by interlocking supply and exhaust

fans. Thus, exhaust should cease when supply airflow is stopped in

areas otherwise maintained at positive or neutral pressure relative

to adjacent spaces. Likewise, supply air should be deactivated

when exhaust airflow is stopped in spaces maintained at a negative

pressure.

Heating and Hot Water Standby Service

When one boiler breaks down or is temporarily taken out of ser-

vice for routine maintenance, the remaining boilers should still be

able to provide hot water for clinical, dietary, and patient use; steam

for sterilization and dietary purposes; and heating for operating,

delivery, birthing, labor, recovery, intensive care, nursery, and gen-

eral inpatient rooms. Some codes or authorities do not require

reserve capacity in climates where a design dry-bulb temperature of

25°F is equaled or exceeded for 99.6% of the total hours in any one

heating period, as noted in the tables in Chapter 14 of the 2017

ASHRAE Handbook—Fundamentals.

Boiler feed, heat circulation, condensate return, and fuel oil

pumps should be connected and installed to provide both normal

and standby service. Supply and return mains and risers for cooling,

heating, and process steam systems should be valved to isolate the

various sections. Each piece of equipment should be valved at the

supply and return ends.

Some supply and exhaust systems for delivery and operating

room suites should be designed to be independent of other fan sys-

tems and to operate from the hospital emergency power system in

the event of power failure. Operating and delivery room suites

should be ventilated such that the hospital retains some surgical and

delivery capability in cases of ventilating system failure.

Boiler steam is often treated with chemicals that may be released

into the air-handling systems serving critical areas where patients

may be more susceptible to respiratory irritation and its complica-

tions. In this case, a clean steam system could be considered for

Fig. 1 Controlling Air Movement through Pressurization

(ASHRAE 2013)

Health Care Facilities 9.7

humidification. ASHRAE Standard 170 provides minimum require-

ments for steam treatment additives where direct injection steam is

used.

Mechanical Cooling

Carefully consider the source of mechanical cooling for clinical

and patient areas. The preferred method is to use an indirect refrig-

erating system using chilled water. When using direct refrigerating

systems, consult codes for specific limitations and prohibitions, and

refer to ASHRAE Standard 15. Until recently, it has been difficult

to maintain desired temperatures and humidity with direct expan-

sion (DX) systems. Newer technology has provided additional

means of maintaining temperature and humidity in spaces. Use care

when selecting DX equipment.

Insulation

Linings in air ducts and equipment must meet the erosion test

method described in Underwriters Laboratories Standard 181. These

linings (including coatings, adhesives, and insulation on exterior

surfaces of pipes and ducts in building spaces used as air supply ple-

nums) should have a flame spread rating of 25 or less and a smoke

developed rating of 50 or less, as determined by an independent test-

ing laboratory, per ASTM Standard E84.

ASHRAE Standard 170 does not allow duct lining to be used

downstream of the second filter bank (final filter). Duct lining with

an impervious cover may be allowed in terminal units, sound atten-

uators, and air distribution devices downstream of the second filter

bank. This lining and cover will be factory installed. Internal insu-

lation of terminal units may be encapsulated with approved materi-

als, but metal lining is preferable. Duct lining should be avoided

except where necessary for acoustical improvement; for thermal

purposes, external insulation should be used. The use of acoustical

materials as duct interior linings, exposed to air movement, should

be carefully reviewed for the application and regulatory standards in

effect. Duct-mounted sound traps, where necessary, should be of the

packless type or have polymer film linings over acoustical fill.

Testing, Adjusting, and Balancing (TAB) and

Commissioning

For existing systems, testing before beginning remodeling con-

struction (preferably before design completion) is usually a good

investment. This early effort provides the designer with information

on actual system performance and whether components are suitable

for intended modifications, as well as discloses additional necessary

modifications.

The importance of TAB for modified and new systems before

patient occupancy cannot be overemphasized. Health care facilities

require validation and documentation of system performance char-

acteristics. Often, combining TAB with commissioning satisfies

this requirement. See Chapters 39 and 44 for information on TAB

and commissioning.

Operations and Maintenance

Without routine inspection and maintenance of HVAC system

components, systems might operate outside of their optimum per-

formance parameters. This variance can affect delivered system per-

formance. Often, manufacturers’ maintenance information applies

only to their components, not the entire system. ASHRAE Standard

180 addresses the often inconsistent practices for inspecting and

maintaining HVAC systems in health care buildings where the pub-

lic may be exposed to the indoor environment. The standard estab-

lishes minimum HVAC inspection and maintenance requirements to

preserve a system’s ability to achieve acceptable thermal comfort,

energy efficiency, and indoor air quality.

The American Society for Healthcare Engineering (ASHE) (of

the American Hospital Association [AHA]) and the International

Facility Management Association (IFMA) jointly published O&M

Benchmarks for Health Care Facilities (ASHE/IFMA 2000). Health

care facility management professionals at 150 different health care

facilities, representing a broad cross section of the field, were sur-

veyed for the report, which discusses facility age and location,

utility costs and practices, maintenance costs and staffing, environ-

mental services, waste streams, linen services, and operational

costs. In addition to common facility benchmarks (e.g., cost per ar-

ea, cost per worker), the report’s analysis also includes metrics that

hospital leaders recognize, such as adjusted patient days and adjust-

ed discharges.

ASHRAE Standard 170 provides recommended operations and

maintenance procedures for certain health care specific rooms in its

Informative Appendix A. Chapter 40 of this volume also discussed

operation and maintenance.

A common cause of operational problems is the control system.

Often, sensors are out of calibration. Maintenance and/or controls

personnel often alter set points and sequences to provide short-term

fixes. Training and persistent commissioning are necessary to keep

the systems operating correctly.

Planning. Standard 170 requires that an operational facility

plan be established to ensure that the number and arrangements of

system components can best support the owner’s operational goals.

The plan should take into account the age and reliability of the

HVAC equipment, capabilities of different areas of the facility and

their criticality to the facility mission, and available personnel

resources. This plan typically examines loss of normal power sce-

narios, loss of certain pieces of HVAC equipment, back-up fuel

sources, redundant systems, temporary measures, and abnormal

events. In the event of power loss, inpatient areas should allow for

potential 24 h operation and nonambulatory patients who may not

be able to be relocated. The capital outlay for imaging and treat-

ment equipment and their associated operating personnel can be

balanced against additional potential outlays for redundant cooling

or other features as adjusted for the risk of failure.

2.3 SPECIFIC DESIGN CRITERIA

There are seven principal divisions of an acute care general

hospital: (1) surgery and critical care, (2) nursing, (3) ancillary,

(4) administration, (5) diagnostic and treatment, (6) sterilizing and

supply, and (7) service. Environmental requirements of each depart-

ment/space in these divisions differ according to their function and

procedures carried out in them. This section describes the functions

of these departments/spaces. ASHRAE Standard 170 provides

details of HVAC design requirements for spaces in the hospital that

directly affect patient care. If additional regulatory or organizational

criteria must be met, refer to those criteria for specific space require-

ments. Close coordination with health care planners and medical

equipment specialists in mechanical design and construction of

health facilities is essential to achieve the desired conditions.

Surgery and Critical Care

No area of the hospital requires more careful control of aseptic

environmental conditions than the surgical suite. Systems serving

operating rooms, including cystoscopy and fracture rooms, require

careful design to minimize concentrations of airborne organisms.

The greatest amount of bacteria found in the operating room

comes from the surgical team and is a result of their activities during

surgery. During an operation, most members of the surgical team are

near the operating table, creating the undesirable situation of con-

centrating contamination in this highly sensitive area.

Operating Rooms. Past studies of operating room air distri-

bution devices (e.g., Memarzadeh and Manning [2002]) and ob-

servation of installations in industrial cleanrooms indicate that

delivering air from the ceiling, with a downward movement to sev-

eral exhaust/return openings located low on opposite walls, is the

9.8 2019 ASHRAE Handbook—HVAC Applications

most effective (and current code requirement for) air movement

pattern to minimize contamination of the surgical field. Complete-

ly perforated ceilings, partially perforated ceilings, and ceiling-

mounted diffusers have been applied successfully (Pfost 1981).

Memarzadeh and Manning (2002) found that a mixture of low and

high exhaust opening locations may work slightly better than either

all-low or all-high locations, with supply air furnished at average

velocities of25 to 35 fpm from a unidirectional laminar-flow ceil-

ing array. It appears that the main factor in the design of the venti-

lation system is the control of the central region of the operating

room (surgical or sterile field). The laminar flow concept generally

represents the best option for an operating room in terms of con-

tamination control, as it results in the smallest percentage of parti-

cles impacting the surgical site. Figure 6 shows a typical operating

room layout.

Operating room setback (night setback or unoccupied setback) is

a proven energy saving strategy in all climates. Love (2011) details

these strategies. Operating room suites are typically used no more

than 8 to 12 h per day (except trauma centers and emergency depart-

ments). Temperature is typically allowed to drift during setback.

Lowering the set point during unoccupied times reduces reheat ener-

gy; however, positive space pressure must be maintained. Design of

the setback solution should consider local climate, facility type, user

needs, existing conditions (where applicable), relevant code require-

ments, and cost. There are several approaches to setback. Each has

trade-offs between the level of control, complexity, and cost. Com-

mon approaches include

• Two-position supply with shutoff dampers in return/exhaust

• Pressure-independent valves on supply and return

• Modulating control damper or terminal box on return

If a return terminal box is used, consider adding a filter upstream

of the terminal box to protect the airflow sensor.

A separate anesthesia waste gas disposal vacuum system should

be provided for removal of trace gases (NFPA Standard 99). One or

more outlets may be located in each operating room to connect the

anesthetic machine scavenger hose.

Although good results have been reported from air disinfection

of operating rooms by irradiation, this method is seldom used. The

reluctance to use irradiation may be attributed to the need for special

designs for installation, protective measures for patients and person-

nel, constant monitoring of lamp efficiency, and maintenance.

Ultraviolet germicidal irradiation (UVGI) air and surface treatments

have emerging applications in health care facilities; see Chapter 60

for general information on their application.

The following conditions are recommended for operating, cath-

eterization, and cystoscopy rooms:

• Temperature set points should be adjustable to suit the surgical

staff, and relative humidity should be maintained within the

required range. Systems should be able to maintain the pro-

grammed space temperature and temperature rates of change for

specialized procedures such as cardiac surgery. Tolerable tem-

perature ranges are not intended to be dynamic control ranges.

Special or supplemental cooling equipment should be considered

if this lower temperature negatively affects energy use for sur-

rounding areas.

• Air pressure should be kept positive with respect to any adjoining

rooms. A differential-pressure-indicating device should be in-

stalled to help monitor air pressure readings in the rooms.

Fig. 2 Operating Room Layout

(ASHRAE 2013)

Health Care Facilities 9.9

Thorough sealing of all wall, ceiling, and floor penetrations are

essential to maintaining pressure differential.

• Humidity and temperature indicators should be located for easy

observation. Occupant control of temperature may result in an

unintended change in relative humidity.

• Filter efficiencies should be in accordance with ASHRAE Stan-

dard 170 and the user’s requirements. Supply air HEPA filtration

has been applied for some orthopedic surgical suites where long

procedures with large open wound sites and significant genera-

tion of aerosols caused by use of surgical tools may occur. HEPA

filtration has also been applied for high-air-change-rate recircula-

tion systems where required by the surgical team.

• Air should be supplied at the ceiling with exhaust/return from at

least two locations near the floor spaced approximately half of the

room apart. Endoscopic, laparoscopic, or thoracoscopic surgery

procedures aided by camera, and robotic or robot-assisted surgery

procedures, require heat-producing equipment in the operating

room. Exhaust/return openings located above this equipment can

capture the more buoyant heated air and prevent it from being re-

entrained in the ceiling supply airstream. The bottom of low open-

ings should be at least 3 in. above the floor. Supply diffusers

should be unidirectional (laminar-flow), located over the patient

and the surgical team. High-induction ceiling or sidewall diffus-

ers should be avoided.

• Total air exchange rates should address lights and equipment

(e.g., blanket and blood warmers, fiber-optic equipment, robotic

consoles) as well as the peak occupancy of the space and the po-

tentially lower temperature required.

• Generally, all humidification should be done at the air handler.

Where there is an unusual requirement for different humidity lev-

els in different ORs, then sufficient lengths of straight, watertight,

drained stainless steel or aluminum duct should be installed

downstream of humidification equipment to ensure complete

evaporation of water vapor before air is discharged into the room.

Consider also providing a viewing window in the ductwork to

allow easy verification of system performance.

Obstetrical Areas. The pressure in the obstetrical department

should be positive or equal to that in other areas.

Delivery (Caesarean) Rooms. The delivery room design should

conform to the requirements of operating rooms.

Recovery Rooms. Because the smell of residual anesthesia

sometimes creates odor problems in recovery rooms, ventilation is

important, and a balanced air pressure relative to that of adjoining ar-

eas should be provided.

Intensive Care Units. These units serve seriously ill patients,

such as postoperative and coronary patients. HVAC is similar to

general inpatient rooms unless used for wound (burn) intensive care.

Nursery Suites. Air movement patterns in nurseries should be

carefully designed to reduce the possibility of drafts. Some codes or

jurisdictions require that air be removed near floor level, with the

bottoms of exhaust openings at least 3 in. above the floor; the rela-

tive efficacy of this exhaust arrangement has been questioned by

some experts, because exhaust air outlets have a minimal effect on

room air movement at the relatively low air exchange rates involved.

Finned-tube radiation and other forms of convection heating should

not be used in nurseries.

Full-Term Nurseries. The nursery should have a positive air pres-

sure relative to the work space and examination room, and any

rooms located between the nurseries and the corridor should be sim-

ilarly pressurized relative to the corridor.

Special-Care Nurseries. This type of nursery is usually equipped

with individual incubators to regulate temperature and humidity. It

is desirable to maintain these same conditions in the nursery proper

to accommodate both infants removed from the incubators and

those not placed in incubators. Pressurization of special-care nurs-

eries should correspond to that of full-term nurseries.

Observation Nurseries. Temperature and humidity requirements

for observation nurseries are similar to those for full-term nurseries.

Because infants in these nurseries have unusual clinical symptoms,

air from this area should not enter other nurseries. A negative air

pressure relative to that of the workroom should be maintained in

the nursery. The workroom, usually located between the nursery

and the corridor, should be pressurized relative to the corridor.

Emergency Rooms. Emergency rooms are typically the most

highly contaminated areas in the hospital because of the condition

of many arriving patients and the large number of persons accom-

panying them. Waiting rooms and triage areas require special con-

sideration due to the potential to house undiagnosed patients with

communicable airborne infectious diseases. Clean-to-dirty direc-

tional airflow and zone pressurization techniques should be main-

tained, to reduce the potential of airborne exposure for health care

personnel assigned to the emergency room reception stations.

Trauma Rooms. Emergency trauma rooms located with the

emergency department should have the same temperature, humidity,

and ventilation requirements as those of other applicable operating

rooms.

Anesthesia Storage Rooms. Anesthesia storage rooms must be

mechanically ventilated in conformance with several detailed re-

quirements in NFPA Standard 99. Building codes may impose ad-

ditional requirements on the storage of compressed gases.

Nursing

Patient Rooms. Each patient room should have individual tem-

perature control. Air pressure in general patient suites can be neutral

in relation to other areas. Most governmental design criteria and

codes require that all air from toilet rooms be exhausted directly out-

doors. The requirement appears to be based on odor control, though

recent research has documented the ability of toilets to generate

droplets and aerosols (Johnson et al. 2013). Where recirculating

room unit systems are used within patient rooms, it is common prac-

tice to exhaust through the adjoining toilet room an amount of air

equal to the amount of outdoor air brought in for ventilation. Venti-

lation of toilets, bedpan closets, bathrooms, and all interior rooms

should conform to applicable codes.

HVAC energy consumption by patient rooms can be a major con-

tributor to a hospital’s overall HVAC energy usage because they are

constantly occupied. This high occupancy rate, along with the

space’s minimum air change requirements, should be a focus of

methods to minimize energy use. Design requirements for mini-

mum air changes may result in excessive reheating of supply air

from central air-handling units in certain climate zones and building

exposures.

Protective Environment Isolation Units. Immunosuppressed

patients (including bone marrow or organ transplant, leukemia,

burn, and AIDS patients) are highly susceptible to diseases. Some

physicians prefer an isolated laminar airflow unit to protect the

patient; others feel that the conditions of the laminar cell have a psy-

chologically harmful effect on the patient and prefer flushing out the

room and reducing pathogens in the air. An air distribution of 12 air

changes per hour (ach) supplied through a nonaspirating diffuser is

often recommended. With this arrangement, the clean air is drawn

across the patient and removed at or near the door to the room. Pro-

tective environment rooms are sometimes treated as clean spaces

with design considerations such as an anteroom, supply air HEPA

filtration, and particle count testing evaluated during design.

In cases where the patient is immunosuppressed but not conta-

gious, positive pressure must be maintained between the patient

room and adjacent area. Some jurisdictions may require an ante-

room, maintenance of differential pressure, and local pressure mon-

itoring or alarming. Exam and treatment rooms for these patients

9.10 2019 ASHRAE Handbook—HVAC Applications

should be controlled in the same manner. Positive pressure should

also be maintained between the entire unit and adjacent areas to pre-

serve clean conditions.

Exceptions to normally established negative and positive pressure

conditions include operating rooms where highly infectious patients

may be treated (e.g., operating rooms in which bronchoscopy or lung

surgery is performed) and infectious isolation rooms that house

immunosuppressed patients with airborne infectious diseases such

as tuberculosis (TB). When a patient is both immunosuppressed and

potentially contagious, combination airborne infectious isolation/

protective environment (combination AII/PE) rooms are pro-

vided. These rooms require an anteroom, which must be either pos-

itive or negative to both the AII/PE room and the corridor or common

space. Either of these anteroom pressurization techniques minimizes

cross contamination between the patient area and surrounding areas,

and may be used depending on local fire smoke management regu-

lations. Pressure controls in the adjacent area or anteroom must

maintain the correct pressure relationship relative to the other adja-

cent room(s) and areas. A separate, dedicated air-handling system to

serve the protective isolation unit simplifies pressure control and air

quality (Murray et al. 1988). Figure 3 shows a typical protective envi-

ronment room arrangement. The differential pressure (DP) sensor

measures the differential pressure between the patient room and the

corridor. If the patient room becomes negative with respect to the

corridor, alarm lights are triggered to alert staff of the change in

pressurization.

Airborne Infection Isolation Unit. The airborne infection iso-

lation (AII) room protects the rest of the hospital from patients’ air-

borne infectious diseases. Multidrug-resistant strains of

tuberculosis have increased the importance of pressurization, air

change rates, filtration, and air distribution design in these rooms

(Rousseau and Rhodes 1993). Temperatures and humidities should

correspond to those specified for patient rooms.

The designer should work closely with health care planners and

the code authority to determine the appropriate isolation room

design. It may be desirable to provide more complete control, with

a separate anteroom used as an air lock to minimize the potential

that aerosol from the patients’ area reach adjacent areas. Design

approaches to airborne infection isolation may also be found in

CDC (2005). AII room exhaust may include HEPA filtration where

there is a concern over recirculation of the exhaust air into nearby

building air intakes or due to concern of the location of where main-

tenance workers may be working. Figure 4 shows a typical AII room

arrangement with an anteroom. The differential pressure (DP) sen-

sor measures the differential pressure between the patient room and

the corridor. If the AII patient room becomes positive with respect

to the corridor, alarm lights are triggered to alert staff.

Some facilities have switchable isolation rooms (rooms that can

be set to function with either positive or negative pressure). CDC

(2005) and FGI (2014a) have, respectively, recommended against

and prohibited this approach. The two drawbacks of this approach

are that (1) it is difficult to maintain the mechanical dampers and

controls required to accurately provide the required pressures, and

(2) it provides a false sense of security to staff who think that this

provision is all that is required to change a room between protective

isolation and infectious isolation, to the exclusion of other sanitizing

procedures.

Biocontainment Treatment Areas (BTAs). These patient treat-

ment areas (also called biocontainment patient care units) are of

increasing interest and should possibly adopt the previously dis-

cussed clean-to-dirty zoning and airflow paradigm. BTAs are spe-

cial and often isolated clinical and supporting areas specifically

designed to minimize nosocomial transmission during treatment of

patients with suspected or confirmed highly contagious and hazard-

ous illnesses. The design focus for these areas is to protect both the

hospital and attending healthcare workers, while providing an envi-

ronment conducive to patient treatment and recovery. This is par-

tially achieved by following protective engineering and design

principles similar to those used in biosafety level 3 and 4 laboratory

facilities (Smith et al. 2006). Exact design features for BTAs can

vary depending on illness, modes of disease transmission, and avail-

able resources, and BTAs may be designed as disease-specific treat-

ment (or triage) areas or for an all-hazards infectious disease

approach. The spectrum of care may be very broad, ranging from

basic medical observation to intensive clinical care. The most pro-

tective BTA design features include a clean-to-dirty single-pass air-

flow design that augments an established clean-to-dirty human and

material workflow. This approach often incorporates separate entry

and exit points from the patient room. Anterooms at the entry point

can be used for donning personal protective equipment (PPE) as

well as clean observation areas for use by unexposed observers.

Patient rooms within the BTA should be under negative pressure and

may benefit from being AII rooms. Key system redundancies (i.e.,

power, HVAC, exhaust) should be considered and incorporated if

integral to the effectiveness of the BTA’s functional intent. Due to

the significant PPE requirements and their corresponding influence

on worker heat stress, the patient room conditioning capacity should

allow for room temperatures below those commonly used for inpa-

tient treatment.

BTA patient rooms should ideally have private bathrooms with

self-closing doors, toilets with fully closing toilet lids (as allowed by

local code and the AHJ), and hands-free electronic faucets. Negative

Fig. 3 Protective Environment Room Arrangement

(ASHRAE 2013)

Fig. 4 Airborne Infection Isolation Room

(ASHRAE 2013)

Health Care Facilities 9.11

air pressure, enhanced exhaust airflow volumes, and strategic

exhaust louver placement to facilitate capture and removal of toilet

plume aerosols are appropriate considerations for such patient bath-

rooms. Exit points and pathways from the patient room should con-

sider issues such as worker/material decontamination and PPE

doffing, sufficient temporary storage for hazardous medical waste,

and exit path routing of wastes and laboratory samples.

A dedicated laboratory capacity may also be incorporated into

the BTA and should be placed in a location that is compatible with

the clean-to-dirty paradigm. Facilities considering more than one

patient room in their BTA may want to consider incorporating a

shared exit-path anteroom to accommodate many of these functions

while optimizing usage of space. Depending on the scope, size, and

capacity of the BTA, dedicated BTA worker restrooms, decontami-

nation showers, changing rooms, PPE storage, and break areas may

be appropriate. Facilities that specialize in pediatric patients may

also consider special observation and/or interactive capabilities

(e.g., specialized glove ports built into wall of clean observation

area) that allow for safe familial interaction with pediatric patients.

Figure 5 contains a sample layout of a biocontainment unit.

Floor Pantry. Ventilation requirements for this area depend

upon the type of food service used by the hospital. Where bulk food

is dispensed and dishwashing facilities are provided in the pantry,

using hoods above equipment with exhaust to the outdoors is

recommended. Small pantries used for between-meal feedings

require no special ventilation. Air pressure of the pantry should be

in balance with that of adjoining areas to reduce air movement in

either direction.

Labor/Delivery/Recovery/Postpartum (LDRP). The proce-

dures for normal childbirth are considered noninvasive, and rooms

are controlled similarly to patient rooms. Some jurisdictions may

require higher air change rates than in a typical patient room. It is

expected that invasive procedures such as cesarean section are per-

formed in a nearby operating room.

Ancillary

Radiology Department. Factors affecting ventilation system

design in these areas include odors from certain clinical treatments

and the special construction designed to prevent radiation leakage.

Fluoroscopic, radiographic, therapy, and darkroom areas require

special attention.

Fluoroscopic, Radiographic, and Deep Therapy Rooms. These

rooms may require a temperature from 78 to 80°F and a relative

humidity from 40 to 50%. This relative humidity range control often

requires dedicated room equipment and control. Depending on the

location of air supply outlets and exhaust intakes, lead lining may be

required in supply and return ducts at points of entry to various clin-

ical areas to prevent radiation leakage to other occupied areas.

Fig. 5 Biocontainment Treatment Areas

(ASHRAE 2013)

9.12 2019 ASHRAE Handbook—HVAC Applications

Darkroom. The darkroom is normally in use for longer periods

than x-ray rooms and should have an exhaust system to discharge air

to the outdoors. Exhaust from the film processor should be con-

nected into the darkroom exhaust system.

Laboratories. Air conditioning is necessary in laboratories for

the comfort and safety of the technicians (Degenhardt and Pfost

1983). Chemical fumes, odors, vapors, heat from equipment, and

the undesirability of open windows all contribute to this need. Pay

particular attention to the size and type of equipment used in the var-

ious laboratories, because equipment heat gain usually constitutes a

major portion of the cooling load; see Table 7 in Chapter 18 of the

2013 ASHRAE Handbook—Fundamentals for examples.

The general air distribution and exhaust systems should be

constructed of conventional materials following standard designs

for the type of systems used. Exhaust systems serving hoods in

which radioactive materials, volatile solvents, and strong oxidizing

agents (e.g., perchloric acid) are used should be made of stainless

steel. Washdown facilities and dedicated exhaust fans should be

provided for hoods and ducts handling perchloric acid.

Hood use may dictate other duct materials. Hoods in which

radioactive, carcinogenic, or infectious materials are to be used

should be equipped with high-efficiency (HEPA) filters for the

exhaust and have a procedure and equipment for safe removal and

replacement of contaminated filters. Exhaust duct routing should be

as short as possible with minimal horizontal offsets and, when pos-

sible, duct portions with contaminated air should be maintained

under negative pressure (e.g., locate fan on clean side of filter). This

applies especially to perchloric acid hoods because of the extremely

hazardous, explosive nature of this material. Hood exhaust fans

should be located at the discharge end of the duct system to prevent

exhaust products entering the building. The hood exhaust system

should not shut off if the supply air system fails. Chemical storage

rooms must have a constantly operating exhaust air system. For fur-

ther information on laboratory air conditioning and hood exhaust

systems, see AIHA Standard Z9.5, Hagopian and Hoyle (1984),

NFPA Standard 45, and Chapter 16 of this volume.

Exhaust air from hoods in biochemistry, histology, cytology,

pathology, glass washing/sterilizing, and serology-bacteriology

units should be discharged to the outdoors with no recirculation.

Use care in designing the exhaust outlet locations and arrange-

ments: exhaust should not be reentrained in the building through

outdoor air intakes or other building openings. Separation from

outdoor air intake sources, wind direction and velocity, building

geometry, and exhaust outlet height and velocity are important. In

many laboratory exhaust systems, exhaust fans discharge vertically

at a minimum of 10 ft above the roof at velocities up to 4000 fpm.

The entire laboratory area should be under slight negative pressure

to reduce the spread of odors or contamination to other hospital

areas. Temperatures and humidities should be within the comfort

range.

Bacteriology Laboratories. These units should not have undue

air movement; limit air velocities to a minimum. The sterile transfer

room, which may be within or adjoining the bacteriology labora-

tory, is where sterile media are distributed and where specimens are

transferred to culture media. To maintain a sterile environment, a

HEPA filter should be installed in the supply air duct near the point

of entry to the room. The media room should be ventilated to

remove odors and steam.

Infectious Disease and Virus Laboratories. These laborato-

ries, found only in large hospitals, require special treatment. A min-

imum ventilation rate of 6 ach or makeup approximately equal to

hood exhaust volume is recommended for these laboratories, which

should have a negative air pressure relative to adjacent areas to help

prevent exfiltration of airborne contaminants. Exhaust air from

fume hoods or safety cabinets must be sterilized before being

exhausted to the outdoors. This may be accomplished by using elec-

tric or gas-fired heaters placed in series in the exhaust systems and

designed to heat the exhaust air to 600°F. A more common and less

expensive method of sterilizing the exhaust is to use HEPA filters in

the system.

Nuclear Medicine Laboratories. Such laboratories administer

radioisotopes to patients orally, intravenously, or by inhalation to fa-

cilitate diagnosis and treatment of disease. There is little opportunity

in most cases for airborne contamination of the internal environment,

but exceptions warrant special consideration. One important excep-

tion involves the use of iodine-131 solution in capsules or vials to

diagnose thyroid disorders. Another involves use of xenon-133 gas

via inhalation to study patients with reduced lung function.

Capsules of iodine-131 occasionally leak part of their contents

before use. Vials emit airborne contaminants when opened for

preparation of a dose. It is common practice for vials to be opened

and handled in a standard laboratory fume hood; a minimum face

velocity of 100 fpm should be adequate for this purpose. This rec-

ommendation applies only where small quantities are handled in

simple operations. Other circumstances may warrant use of a glove

box or similar confinement. Diagnostic use of xenon-133 involves a

special instrument that allows the patient to inhale the gas and to

exhale back into the instrument. The exhaled gas is passed through

a charcoal trap mounted in lead, and is often vented outdoors. The

process suggests some potential for escape of the gas into the inter-

nal environment.

Because of the specialized nature of these operations and of the

equipment involved, it is recommended that system designers deter-

mine the specific instrument to be used and contact the manufac-

turer for guidance. Other guidance is available in U.S. Nuclear

Regulatory Commission Regulatory Guide 10.8 (NRC 1980). In

particular, emergency procedures in case of accidental release of

xenon-133 should include temporary evacuation of the area and/or

increasing the ventilation rate of the area. Recommendations for

pressure relationships, supply air filtration, supply air volume, air-

borne particle counts, recirculation, and other attributes of supply

and discharge systems for histology, pathology, pharmacy, and

cytology laboratories are also relevant to nuclear medicine labora-

tories. The NRC does, however, impose some special ventilation

system requirements where radioactive materials are used. For

example, NRC (1980) provides a computational procedure to esti-

mate the airflow necessary to maintain xenon-133 gas concentration

at or below specified levels. It also contains specific requirements as

to the amount of radioactivity that may be vented to the atmosphere;

the disposal method of choice is adsorption onto charcoal traps.

Autopsy Rooms. Susceptible to heavy bacterial contamination

(e.g., tuberculosis) and odor, autopsy rooms must maintain a nega-

tive air pressure relative to adjoining rooms or the corridor to help

prevent the spread of contamination (Murray et al. 1988). Autopsy

rooms are part of the hospital’s pathology department and require

special attention (CDC 2005). Exhaust intakes should be located

both at the ceiling and in the low sidewall. Where large quantities of

formaldehyde are used, special exhaust systems can effectively con-

trol concentrations below legal exposure limits. A combination of

localized exhaust and ventilation systems with downdraft or side-

draft tables has been shown to effectively control concentrations

while using smaller exhaust volumes than those required by dilution

ventilation (Gressel and Hughes 1992). In smaller hospitals where

the autopsy room is used infrequently, local control of the ventila-

tion system and an odor control system with either activated char-

coal or potassium permanganate-impregnated activated alumina

may be sufficient.

Animal Quarters. Principally because of odor, animal quarters

(found only in larger research hospitals) require a mechanical ex-

haust system that discharges contaminated air above the hospital roof

and maintains a negative air pressure relative to adjoining areas to

Health Care Facilities 9.13

help prevent the spread of odor, allergens, or other contaminants.

Chapter 16 has further information on animal room air conditioning.

Pharmacies. Design and ventilation requirements for pharma-

cies can vary greatly according to the type of compounding per-

formed within the space. Pharmacies handling hazardous drugs and/

or involved in sterile compounding activities have special require-

ments for incorporating primary engineering controls (PECs) such

as horizontal or vertical laminar-airflow workbenches (LAFW),

biological safety cabinets (BSC), and compounding (barrier) iso-

lators. Room air distribution and filtration must be coordinated

with any PECs that may be needed. See Chapters 16 and 18 for

more information.

Sterile Compounding. Sterile pharmaceutical compounding re-

quirements are prescribed by USP (2008). USP Chapter 797 is en-

forceable under the U.S. Food and Drug Administration, is adopted

in whole or in part by many state boards of pharmacy, and may be

incorporated into the inspection programs of health care accredita-

tion organizations. The Joint Commission recognized USP 797 as a

consensus-based safe practice guideline for sterile compounding;

however, they do not require its direct implementation as a condi-

tion of accreditation. End users, owners, architects, and engineers

should consult the most recent release of USP 797, which is under

continuous maintenance, as well as applicable sterile compounding

design guidance adopted by their state boards of pharmacy.

USP 797 prescribes that all sterile pharmaceutical preparations

to be administered more than 1 h after preparation must be com-

pounded entirely within a critical work zone protected by a unidi-

rectional, HEPA-filtered airflow of ISO class 5 (former class 100

under withdrawn Federal Standard 209E; see Chapter 18 for class

definitions) or better air quality. This ISO class 5 environment is

generally provided using a primary engineering control (PEC) such

as a LAFW, BSC, or compounding isolator. USP 797 also requires

that the ISO class 5 critical work zone be placed within a buffer area

(also called a buffer room or cleanroom) (the air quality of which

must meet a minimum of ISO class 7) and contain air-conditioning

and humidity controls. Adjacent to the buffer area, the sterile com-

pounding pharmacy design must incorporate an ante area for stor-

age, hand washing, nonsterile preparation activities, donning and

doffing of protective overgarments, etc. The air cleanliness in the

ante area must be a minimum of ISO class 8 (exception: see the fol-

lowing Hazardous Drugs section). The ante area and buffer area

constitute secondary engineering controls. Low-risk preparations

that are nonhazardous and destined for administration within 12 h of

compounding are granted an exemption from these secondary engi-

neering controls if they are prepared within an ISO class 5 PEC and

the compounding area is segregated from noncompounding areas.

Pharmacy designers should note that the ISO class 5, 7, and 8 air

cleanliness requirements are specified for dynamic conditions (USP

2008). Although ASHRAE Standard 170 does not prescribe a de-

sign temperature for health care pharmacies, USP 797 recommends

a maximum temperature of 68°F because of the increased thermal

insulation that results from wearing protective clothing and the ad-

verse sterility conditions that could arise from uncomfortably warm

and/or sweaty pharmacy workers.

Beyond air quality requirements, the physical design features sep-

arating the buffer area from the ante area are based on the pharmacy’s

compounded sterile preparation (CSP) risk level (low, medium, or

high) for microbial, chemical, and physical contamination. USP 797

instructs pharmacy professionals on how to determine their phar-

macy’s CSP risk level based on purity and packaging of source

materials, quantity and type of pharmaceuticals, time until its admin-

istration, and various other factors. The desired CSP risk level capa-

bility should be identified before designing the pharmacy design

layout. Pharmacies intended for compounding high-risk-level CSPs

require a physical barrier with a door to separate the buffer room

from the anteroom, and the buffer room must be maintained at a

minimum positive pressure differential of 0.02 in. of water. For me-

dium- and low-risk level CSPs, the buffer area and ante area can be

in the same room, with an obvious line of demarcation separating the

two areas and with the demonstrable use of displacement airflow,

flowing from the buffer area towards the ante area. Depending on the

affected cross-sectional area and the moderately high velocity re-

quired to maintain the displacement uniformity (typically 40 fpm or

greater), designers may find the physical barrier design to be a more

energy friendly approach. USP further prescribes areas to receive a

minimum of 30 ach (with up to 15 of these provided by the PEC) if

the area is designated to be ISO class 7. There is no minimum venti-

lation requirement prescribed for ISO class 8 ante areas (USP 2008).

Selecting pharmacy PECs can be a delicate task. Class II BSCs

are currently certified following the construction and performance

guidelines developed by the National Sanitation Foundation (NSF)

and adopted by the American National Standards Institute (ANSI/

NSF Standard 49-2014). However, no such national certification

program exists for compounding isolators. USP 797 addresses this

shortcoming by referencing isolator testing and performance guide-

lines developed by the Controlled Environment Testing Association

(CETA 2006).

Hazardous Drugs. Compounding hazardous drugs is another

pharmaceutical operation that requires special design consider-

ations. NIOSH (2004) warned of the dangers of occupational expo-

sures to hazardous drugs, over 130 of which were defined and

identified; roughly 90 of these drugs were antineoplastic agents pri-

marily used during cancer treatments. Several of NIOSH’s recom-

mended protective measures can affect a pharmacy’s ventilation

design and physical layout. These recommendations include the fol-

lowing:

• Prepare hazardous drugs in an area devoted to that purpose alone

and restricted to authorized personnel.

• Prepare hazardous drugs inside a ventilated cabinet designed to

prevent hazardous drugs from being released into the work envi-

ronment.

• Use a high-efficiency particulate air (HEPA) filter for exhaust

from ventilated cabinets and, where feasible, exhaust 100% of the

filtered air to the outdoors, away from outdoor air intakes or other

points of entry.

• Place fans downstream of HEPA filters so that contaminated ducts

and plenums are maintained under negative pressure.

• Design the exhaust system such that negative pressure is main-

tained in the cabinet in the event of fan failure.

• Do not use ventilated cabinets (BSCs or compounding aseptic

containment isolators [CACIs]) that recirculate air inside the cab-

inet or that exhaust air back into the pharmacy unless the hazard-

ous drug(s) in use will not volatilize (evaporate or sublimate)

while they are being handled or after they are captured by the

HEPA filter. (Note: This recommendation is a shift from tradi-

tional pharmacy design practice and involves knowledge of the

physical properties of drugs within the current drug formulary as

well as future new drugs that might be compounded within the

cabinet. Within-cabinet recirculation [e.g., BSC class II Type A2

or B1] is allowed when airstream has zero or only minute vapor

drug contaminant.)

• Store hazardous drugs separately from other drugs, in an area with

sufficient general exhaust ventilation to dilute and remove any

airborne contaminants. Depending on the physical nature and

quantity of the stored drugs, consider installing a separate, high-

volume, emergency exhaust fan capable of quickly purging air-

borne contaminants from the storage room in the event of a spill,

to prevent airborne migration into adjacent areas.

The American Society of Health Systems Pharmacists’ Guide-

lines on Handling Hazardous Drugs (ASHP 2006) adopted NIOSH’s

(2004) protective equipment recommendations, and added the

9.14 2019 ASHRAE Handbook—HVAC Applications

specification that hazardous drug compounding should be done in a

contained, negative-pressure environment or one that is protected

by an airlock or anteroom.

Often, hazardous drugs also require sterile compounding. If so,

pharmacies must have an environment suitable for both product ste-

rility and worker protection. ASHP (2006), NIOSH (2004), and

USP (2008) all address these dual objectives by recommending the

use of BSCs or compounding aseptic containment isolators. The

precautionary recommendations regarding in-cabinet recirculation

and cabinet-to-room recirculation of air potentially contaminated

with hazardous drugs still apply. In addition, USP 797 requires haz-

ardous drug sterile compounding to be conducted in a negative-

pressure compounding area and to be stored in dedicated storage

areas with a minimum of 12 ach of general exhaust. When CACIs

are used outside of an ISO 7 buffer area, the compounding area must

maintain a negative pressure of 0.01 in. of water and also have a

minimum of 12 ach. Anterooms adjacent to an ISO 7 buffer area

must also be ISO 7, since there will be air leakage from the ante-

room into the negative pressure hazardous drug buffer area.

Table 4 provides a matrix of design and equipment decision logic

based on USP 797 and NIOSH (2004).

In February 2016, USP published a new pharmaceutical standard

identified as general chapter 800: Hazardous Drugs—Handling in

Healthcare Settings. The new chapter applies to all hazardous drug

compounding, whereas the previously published guidance in USP

797 was only applicable to sterile compounding. As a USP chapter

numbered less than 1000, it is federally enforceable, as well as

adoptable (in whole or in part) by individual state boards of phar-

macy. Although published in 2016, USP 800 has an official imple-

mentation date of December 1, 2019 to allow health care facilities

sufficient time to implement necessary engineering design require-

ments. The USP 800 chapter applies to all health care facilities

(including veterinary facilities) where hazardous drugs are handled,

manipulated, stored, or distributed. Most of the guidance for haz-

ardous drug sterile compounding carries over from USP 797, but

there are two major changes: (1) the low-volume exemption men-

tioned in Table 3 no longer applies, and (2) USP 800 allows low-to-

medium risk sterile compounding to occur in an ISO 5 PEC placed

in a nonclassified area (segregated compounding area) in accor-

dance with USP 797 use limitations. The USP 800 chapter adopts a

reception-through-administration approach to protecting health

care workers from hazardous drug exposures and provides specified

requirements for receiving, storing, mixing, preparing, compound-

ing, dispensing, and administering hazardous drugs. Most of these

requirements include an engineering and/or architectural design

component are summarized in Table 5.

Administration

This department includes the main lobby and admitting, medical

records, and business offices. Admissions and waiting rooms may

harbor patients with undiagnosed airborne infectious diseases, so

consider using local exhaust systems that move air toward the ad-

mitting patient. A separate air-handling system is considered desir-

able to segregate this area from the hospital proper, because it is

usually unoccupied at night and thus a good candidate for energy

savings control solutions. Open-water features are strongly discour-

aged inside health care occupancies; if closed water features are

proposed, provide water treatment and other administrative and en-

gineering controls to protect occupants from infectious or irritating

aerosols. Refer to ASHRAE Standard 188-2015 and Guideline 12

for further guidance.

Diagnostic and Treatment

Bronchoscopy, Sputum Collection, and Pentamidine Ad-

ministration Procedures. These procedures have a high potential

for discharges of potentially infectious droplet nuclei into the

room air via coughing. Bronchoscopy procedures can release

airborne aerosols into the room from a patient who could possibly

be diagnosed with tuberculosis, and nontherapeutic exposures to

pentamidine are an additional exposure concern. The procedures

and patient recovery period (when excessive coughing may occur)

are best suited for an airborne infectious isolation (AII) room.

ASHRAE Standard 170 requires local capture exhaust (enclosed

administration booth, enclosing hood or tent) near the

bronchoscopy procedure site along with exhaust and pressurization

similar to an AII room.

Magnetic Resonance Imaging (MRI) Rooms. These rooms

should be treated as exam rooms in terms of temperature, humidity,

and ventilation. However, special attention is required in the control

room because of the high heat release of computer equipment, and in

the exam room because of the cryogens used to cool the magnet.

Nonferrous material requirements and shielding penetrations should

be in accordance with the specific manufacturer’s requirements.

Heat Gains from Medical Equipment. Table 6 in Chapter 18 of

the 2017 ASHRAE Handbook—Fundamentals tabulates typical heat

gain from many types of smaller mobile medical equipment. ASH-

RAE research project RP-1343 (Koenigshofer et al. 2009) devel-

oped methods to test heat gain from large, fixed medical imaging

equipment systems at both idle and peak outputs during operational

cycles. Tables 6 and 7 present results for some of the equipment test-

ed in RP-1343. Medical equipment heat outputs can vary widely

among different manufacturers, even for equipment that performs a

similar function, and the medical equipment field is rapidly advanc-

ing. The functional program should identify specific manufacturers

and models for the HVAC designer’s use early in the design process.

Treatment Rooms. Patients are brought to these rooms for spe-

cial treatments (e.g., hyperbaric oxygen therapy) that cannot be con-

veniently administered in patient rooms. To accommodate the

patient, the rooms should have independent temperature and humid-

ity control. Temperatures and humidities should correspond to those

specified for patients’ rooms.

Table 4 Minimum Environmental Control Guidance for Pharmacies

Compounding Scenario Hazardous Drug (HD) (Requires separate area) Nonhazardous Drug

Sterile compounding to be

administered within 12 h

ISO 5 CACI or BSC within negative-pressure ISO 7

buffer + ISO 7 ante areas

If immediate use and low risk: no environmental requirements if admin-

istered <12 h + ISO 5 PEC within segregated compounding area

Sterile compounding to be

administered after 12 h or

ISO 5 CACI or BSC within negative-pressure ISO 7

buffer + ISO 7 ante areas

ISO 5 PEC + ISO 7 buffer + ISO 8 ante areas

- High-risk compounding requires physical barrier with min. positive

pressure (0.02 in. of water) in buffer room relative to anteroom

- Medium- and low-risk compounding may use physical barrier (as per

high risk) or a clearly identified line of demarcation between buffer and

ante areas with uniform displacement airflow (min. of 40 fpm recom-

mended) in direction of buffer to ante areas

Nonsterile compounding Needs compounding containment isolator or BSC No sterility or occupational exposure controls required

*For facilities that prepare a low volume of hazardous drugs and use two tiers of containment (e.g., CSTD within CACI or BSC), a negative-pressure buffer area is not required.

Health Care Facilities 9.15

Physical Therapy Department. The cooling load of the electro-

therapy section is affected by the shortwave diathermy, infrared, and

ultraviolet equipment used in this area.

Hydrotherapy Section. This section, with its various water treat-

ment baths, is generally maintained at temperatures up to 80°F. The

potential latent heat load in this area should not be overlooked. The

exercise section requires no special treatment; temperatures and

humidities should be within the comfort zone. Air may be recircu-

lated within the areas, and an odor control system is suggested.

Occupational Therapy Department. In this department, spaces

for activities such as weaving, braiding, artwork, and sewing require

no special ventilation treatment. Air recirculation in these areas

using medium-grade filters in the system is permissible. Larger hos-

pitals and those specializing in rehabilitation may offer patients a

greater diversity of skills to learn and craft activities, including car-

pentry, metalwork, plastics, photography, ceramics, and painting.

The air-conditioning and ventilation requirements of the various

sections should conform to normal practice for such areas and to the

codes relating to them. Temperatures and humidities should be

maintained within comfort levels.

Inhalation Therapy Department. This department treats pul-

monary and other respiratory disorders. The air must be very clean,

and the area should have a positive pressure relative to adjacent

areas, except when the patient may also be airborne infectious or

when the treatment regimen uses hazardous drug therapies. Local

exhaust ventilation controls (e.g., administration booth, enclosing

hood or tent) should be provided to control exposure of staff to haz-

ardous drug therapies.

Workrooms. Clean workrooms serve as storage and distribution

centers for clean supplies and should be maintained at a positive

pressure relative to the corridor. Soiled workrooms serve primarily as

collection points for soiled utensils and materials. They are consid-

ered contaminated rooms and should have a negative air pressure rel-

ative to adjoining areas. Temperatures and humidities should be in

the comfort range and account for protective clothing requirements

required for the room occupants.

Decontamination, High-Level Disinfection,

Sterilization and Supply

Used and contaminated utensils, instruments, and equipment are

brought to this unit for decontamination and high level disinfection

or sterilization before reuse. The central sterile processing unit usu-

ally consists of a decontamination area, a sterile prep area, a steriliz-

ing area, and a sterile storage area where supplies are kept until

requisitioned. The decontamination area must be physically sepa-

rated from the sterile prep and sterilization areas. A dedicated endo-

scope reprocessing area may support the inpatient endoscopy suite.

Although AAMI allows for decontamination and high level disinfec-

tion to be located in the same space, a clear line of demarcation

between soiled cleaning activities and the clean manual or automated

disinfection activities. Air should flow from the clean disinfection

area toward the contaminated cleaning area (ANSI/AAMI Standard

58:2013). Air pressure relationships should conform to those indi-

cated in ASHRAE Standard 170. Temperature and humidity should

be within the comfort range. Pay special attention to equipment used

in these areas (gaps in disinfection/cleaning equipment and piping

penetrations between decontamination and clean rooms) to maintain

pressurization requirements.

The following guidelines are important in the central sterilizing

and supply unit:

• Insulate sterilizers to reduce heat load.

• Amply ventilate sterilizer equipment closets to remove excess

heat.

• Where ethylene oxide (ETO) gas sterilizers are used, provide a

separate exhaust system with terminal fan (Samuals and Eastin

Table 5 Engineering Requirements for Receiving, Storing, and Manipulating Hazardous Drugs

Activity Minimum Engineering Requirements

Hazardous drug receipt/unpacking Segregated area at negative or neutral pressure to surrounding areas

Hazardous drug storage* Segregated area, externally vented, (0.01 in. of water) negative pressure, 12

ach

Nonsterile HD compounding Containment, primary engineering control (C-PEC): externally vented (pre-

ferred) or redundant HEPA filtered.

Containment, secondary engineering control (C-SEC): externally vented,

(0.01 in. of water) negative pressure, 12 ach

Sterile HD compounding (two allowable configurations):

Buffer room configuration C-PEC: ISO 5 direct compounding area, externally vented [e.g. Class II

(Types A2, B1 or B2), Class III BSC or CACI]

C-SEC: externally vented, ISO 7 buffer area, (0.01 in. of water) negative pres-

sure, 30 ach plus ISO 7 anteroom, (0.02 in. of water) positive pressure relative

to all adjacent unclassified areas, 30 ach

Segregated compounding area configuration (for low- and medium-risk

compounding use only; see USP 797 for compounding risk determinations)

Nonclassified air cleanliness, 12 ach, 0.01 in. of water negative pressure

*Non-antineoplastic-reproductive risk only, and final dosage forms of antineoplastic HDs may be stored with other inventory if permitted by entity policy.

Table 6 Summary of Heat Gain to Air from Imaging Systems

System

Maximum

60 min

Time-Weighted

Average, Btu/h

Calculated

Idle,

Btu/h

Manufacturer’s

Design

Information,

Btu/h

MRI #1 83,331 75,873 —

MRI #2 80,475 65,323 —

X-ray 4,258 3,692 4,604

Fluoroscopy #1 41,384 31,322 24,946

Fluoroscopy #2 17,100 15,105 20,123

CT–64 slice 24,085 22,437 65,450

PET/CT 43,008 33,438 —

Nuclear camera 3,790 3,620 —

Linear accelerator 111,238 67,807 31,249

Ultrasound (portable) 2,927 1,692 —

Cyberknife 45,720 35,440 —

Table 7 Summary of Heat Gain to Air

Equipment Calculated Idle, Btu/h High, Btu/h

Dialysis machine 1356 2342

Film processor 1367 1427

Pharmacy freezer 2478 2787

Pharmacy refrigerator 1653 1997

9.16 2019 ASHRAE Handbook—HVAC Applications

1980). Provide adequate exhaust capture velocity in the vicinity

of sources of ETO leakage. Install an exhaust at sterilizer doors

and over the sterilizer drain, and exhaust flammable storage cab-

inets and sterilant cylinder supply cabinets. Exhaust aerator and

service rooms. Sterilizers should be equipped with automatic aer-

ation functionality. Audible and visual ETO alarm sensors and

exhaust flow sensors should also be provided and monitored.

ETO sterilizers should be located in dedicated unoccupied rooms

that have a highly negative pressure relative to adjacent spaces

and 10 ach. Many jurisdictions require that ETO exhaust systems

have equipment to remove ETO from exhaust air (see OSHA

Standard 29 CFR 1910.1047).

• Similar provisions for monitoring and alarms should be consid-

ered for hydrogen peroxide sterilizers.

• Maintain storage areas for sterile supplies at a relative humidity of

no more than 50%.

Service

Service areas include dietary, housekeeping, biohazardous waste

storage, mechanical, and employee facilities. Whether these areas

are conditioned or not, adequate ventilation is important to provide

sanitation and a wholesome environment. Ventilation of these areas

cannot be limited to exhaust systems only; provision for supply air

must be incorporated into the design. Such air must be filtered and

delivered at controlled temperatures. The best designed exhaust sys-

tem may prove ineffective without an adequate air supply. Ex-

perience shows that relying on open windows results only in

dissatisfaction, particularly during the heating season. Air-to-air heat

exchangers in the general ventilation system offer possibilities for

sustainable operation in these areas.

Dietary Facilities. These areas usually include the main kitchen,

bakery, dietitian’s office, dishwashing room, and dining space.

Because of the various conditions encountered (i.e., high heat and

moisture production, cooking odors), special attention in design is

needed to provide an acceptable environment. See Chapter 34 for

information on kitchen facilities.

The dietitian’s office is often located within the main kitchen or

immediately adjacent to it. It is usually completely enclosed for pri-

vacy and noise reduction. Air conditioning is recommended for

maintaining normal comfort conditions.

The dishwashing room should be enclosed and minimally venti-

lated to equal the dishwasher hood exhaust. It is not uncommon for

the dishwashing area to be divided into a soiled area and a clean

area. In such cases, the soiled area should be kept at a negative pres-

sure relative to the clean area.

Ventilation of the dining space should conform to local codes.

The reuse of dining space air for ventilation and cooling of food

preparation areas in the hospital is suggested, provided the reused

air is passed through filters with a filtration efficiency of MERV 13

or better. Where cafeteria service is provided, serving areas and

steam tables are usually hooded. The air-handling capacities of

these hoods should be sized to accommodate exhaust flow rates (see

Table 6 in Chapter 34). Ventilation systems for food preparation and

adjacent areas should include an interface with hood exhaust con-

trols to assist in maintaining pressure relationships.

Kitchen Compressor/Condenser Spaces. Ventilation of these

spaces should conform to all codes, with the following additional

considerations: (1) 350 cfm of ventilating air per compressor horse-

power should be used for units located in the kitchen; (2) condensing

units should operate optimally at 90°F maximum ambient tempera-

ture; and (3) where air temperature or air circulation is marginal,

specify combination air- and water-cooled condensing units. It is

often worthwhile to use condenser water coolers or remote condens-

ers. Consider using heat recovery from water-cooled condensers.

Laundry and Linen Facilities. Of these facilities, only the

soiled linen storage room, soiled linen sorting room, soiled utility

room, and laundry processing area require special attention. The

room for storing soiled linen before pickup by commercial laundry

is odorous and contaminated, and should be well ventilated, ex-

hausted, and maintained at a negative air pressure. The soiled utility

room is provided for inpatient services and is normally contaminat-

ed with noxious odors. This room should be mechanically exhaust-

ed directly outdoors.

In the laundry processing area, equipment such as washers, flat-

work ironers, and tumblers should have direct overhead exhaust to

reduce humidity. Such equipment should be insulated or shielded

whenever possible to reduce the high radiant heat effects. A canopy

over the flatwork ironer and exhaust air outlets near other heat-pro-

ducing equipment capture and remove heat best. Air supply inlets

should be located to move air through the processing area toward the

heat-producing equipment. The exhaust system from flatwork iron-

ers and tumblers should be independent of the general exhaust sys-

tem and equipped with lint filters. Air should exhaust above the roof

or where it will not be obnoxious to occupants of other areas. Heat

reclamation from the laundry exhaust air may be desirable and prac-

ticable.

Where air conditioning is contemplated, a separate supplemen-

tary air supply, similar to that recommended for kitchen hoods, may

be located near the exhaust canopy over the ironer. Alternatively,

consider spot cooling for personnel confined to specific areas.

Mechanical Facilities. The air supply to boiler rooms should

provide both comfortable working conditions and the air quantities

required for maximum combustion of the particular fuel used.

Boiler and burner ratings establish maximum combustion rates, so

the air quantities can be computed according to the type of fuel. Suf-

ficient air must be supplied to the boiler room to supply the exhaust

fans as well as the boilers.

At workstations, the ventilation system should limit tempera-

tures to 90°F effective temperature. When ambient outdoor air

temperature is higher, indoor temperature may be that of the out-

door air up to a maximum of 97°F to protect motors from exces-

sive heat.

Maintenance Shops. Carpentry, machine, electrical, and plumb-

ing shops present no unusual ventilation requirements. Proper ven-

tilation of paint shops and paint storage areas is important because

of fire hazard and should conform to all applicable codes. Mainte-

nance shops where welding occurs should have exhaust ventilation.

3. OUTPATIENT HEALTH CARE

FACILITIES

An outpatient health care facility may be a free-standing unit,

part of an acute care facility, or part of a medical facility such as a

medical office building (clinic). Any outpatient surgery is per-

formed without anticipation of overnight stay by patients (i.e., the

facility operates 8 to 10 h per day).

If physically connected to a hospital and served by the hospital’s

HVAC systems, spaces within the outpatient health care facility

should conform to requirements in the section on Hospital Facili-

ties. Outpatient health care facilities that are totally detached and

have their own HVAC systems may be categorized as diagnostic

clinics, treatment clinics, or both. Many types of outpatient health

care facilities have been built with many combinations of different

programmed uses occurring in a single building structure. Some of

the more common types include primary care facilities, freestanding

emergency facilities, freestanding outpatient diagnostic and treat-

ment facilities, freestanding urgent care facilities, freestanding can-

cer treatment facilities, outpatient surgical facilities, gastrointestinal

endoscopy facilities, renal dialysis centers, outpatient psychiatric

Health Care Facilities 9.17

centers, outpatient rehabilitation facilities, freestanding birth cen-

ters, and dental centers.

When specific treatments in these outpatient facilities are medi-

cally consistent with hospital-based treatments, then environmental

design guidance for hospitals should also apply to the outpatient

treatment location. Information under the Hospital Facilities part of

this chapter may also be applicable to outpatient occupancies per-

forming a similar activity. Outpatient and clinic facilities should

generally be designed according to criteria shown in ASHRAE

Standard 170, unless those criteria conflict with local or state require-

ments.

3.1 DIAGNOSTIC AND TREATMENT CLINICS

A diagnostic clinic is a facility where ambulatory patients are

regularly seen for diagnostic services or minor treatment, but where

major treatment requiring general anesthesia or surgery is not per-

formed. Diagnostic clinics may use specialized medical imaging

equipment, which may be portable cart-mounted items or large per-

manently mounted pieces with adjoining control rooms and equip-

ment rooms. The equipment may require a minimum relative

humidity for proper operation. Heat gains from equipment can be

large; see Table 5 and the equipment manufacturer’s recommenda-

tions.

A treatment clinic is a facility where major or minor procedures

are performed on an outpatient basis. These procedures may render

patients temporarily incapable of taking action for self-preservation

under emergency conditions without assistance from others (NFPA

Code 101).

Design Criteria

See the following subsections under Hospital Facilities:

• Infection Sources

• Control Measures

• Air Quality

• Air Movement

• Temperature and Humidity

• Smoke Control

An outpatient recovery area may not need to be considered a sen-

sitive area, depending on the patients’ treatments. Infection control

concerns are the same as in an acute care hospital. Minimum venti-

lation rates, desired pressure relationships and relative humidity,

and design temperature ranges are similar to the requirements for

hospitals in ASHRAE Standard 170.

The following departments in an outpatient treatment clinic have

design criteria similar to those in hospitals:

• Surgical: operating, recovery, and anesthesia storage rooms

• Ancillary

• Diagnostic and treatment

• Decontamination, high-level disinfection, sterilization, and sup-

ply

• Service: soiled workrooms, mechanical facilities, and locker

rooms

3.2 DENTAL CARE FACILITIES

Institutional dental facilities include reception and waiting areas,

treatment rooms (called operatories), and workrooms where sup-

plies are stored and instruments are cleaned and sterilized; they may

include laboratories where restorations are fabricated or repaired.

Many common dental procedures generate aerosols, dusts, and

particulates (Ninomura and Byrns 1998). The aerosols/dusts may

contain microorganisms (both pathogenic and benign), metals (e.g.,

mercury fumes), and other substances (e.g., silicone dusts, latex

allergens). Some measurements indicate that levels of bioaerosols

during and immediately following a procedure can be extremely

high (Earnest and Loesche 1991). Lab procedures have been shown

to generate dusts and aerosols containing metals. At this time, only

limited information and research are available on the level, nature,

or persistence of bioaerosol and particulate contamination in dental

facilities. Consider using local exhaust ventilation (possibly recir-

culating with HEPA filtration) to help capture and control these

aerosols, because dental care providers and patients are often close

together.

Nitrous oxide is used as an analgesic/anesthetic gas in many

facilities. The design for controlling nitrous oxide should consider

that nitrous oxide (1) is heavier than air and may accumulate near

the floor if air mixing is inefficient, and (2) should be exhausted

directly outdoors. Use active waste gas scavenging to prevent accu-

mulation of waste gases during dental procedures; passive scaveng-

ing through an open window or a vent in the wall should not be used.

3.3 CONTINUITY OF SERVICE AND

ENERGY CONCEPTS

Some owners may desire standby or emergency service capabil-

ity for the heating, air-conditioning, and service hot-water systems

and that these systems be able to function after a natural disaster.

To reduce utility costs, use energy-conserving measures such as

recovery devices, variable air volume, load shedding, or devices to

shut down or reduce ventilation of certain areas when unoccupied.

Mechanical ventilation should take advantage of outdoor air by

using an economizer cycle (when appropriate) to reduce heating and

cooling loads.

The section on Facility Design and Operation includes informa-

tion on zoning and insulation that applies to outpatient facilities as

well.

4. RESIDENTIAL HEALTH, CARE,

AND SUPPORT FACILITIES

FGI’s (2014b) Guidelines for Design and Construction of Resi-

dential Health, Care, and Support Facilities discusses requirements

for nursing homes, hospice facilities, assisted living facilities, inde-

pendent living settings, adult day care facilities, wellness centers,

and outpatient rehabilitation centers. HVAC design requirements

for these spaces, and consequently applicability of ASHRAE stan-

dards to their design, can vary greatly. ASHRAE Standard 170

addresses assisted living, hospice, and nursing facilities. ASHRAE

Standard 62.1 or 62.2 may be applicable to other types of commer-

cial space design, if they are nontransient and residential in nature.

Nursing Facilities

Nursing facilities may be classified as follows:

Extended care facilities are for recuperation by hospital patients

who no longer require hospital facilities but do require the thera-

peutic and rehabilitative services of skilled nurses. This type of

facility is either a direct hospital adjunct or a separate facility with

close ties with the hospital. Clientele may be of any age, usually

stay from 35 to 40 days, and usually have only one diagnostic prob-

lem.

Skilled nursing homes care for people who require assistance in

daily activities; many of them are incontinent and nonambulatory,

and some are disoriented. Residents may come directly from their

homes or from residential care homes, are generally elderly (with an

average age of 80), stay an average of 47 months, and frequently

have multiple diagnostic problems.

Residential care homes are generally for elderly people who are

unable to cope with regular housekeeping chores but have no acute

ailments and are able to care for all their personal needs, lead normal

9.18 2019 ASHRAE Handbook—HVAC Applications

lives, and move freely in and out of the home and the community.

These homes may or may not offer skilled nursing care. The average

length of stay is four years or more.

Functionally, these buildings have five types of areas that are of

concern to the HVAC designer: (1) administrative and support areas

inhabited by staff, (2) patient areas that provide direct normal daily

services, (3) treatment areas that provide special medical services,

(4) clean workrooms for storing and distributing clean supplies, and

(5) soiled workrooms for collecting soiled and contaminated sup-

plies and for sanitizing nonlaundry items.

4.1 DESIGN CONCEPTS AND CRITERIA

Nursing homes occupants are usually frail, and many are incon-

tinent. Though some occupants are ambulatory, others are bedrid-

den, suffering from advanced illnesses. The selected HVAC and air

distribution system must dilute and control odors and should not

cause drafts. Local climatic conditions, costs, and designer judg-

ment determine the extent and degree of air conditioning and

humidification. Odor may be controlled with large volumes of

outdoor air and heat recovery. To conserve energy, odor may be

controlled with activated carbon or potassium permanganate-

impregnated activated alumina filters instead.

Temperature control should be on an individual room basis. In

geographical areas with severe climates, patient rooms may have

supplementary heat along exposed walls. In moderate climates (i.e.,

where outdoor winter design conditions are30°F or above), over-

head heating may be used.

Controlling airborne pathogen levels in nursing homes is not as

critical as it is in acute care hospitals. Nevertheless, the designer

should be aware of the necessity for odor control, filtration, and air-

flow control between certain areas.

ASHRAE Standard 170 lists recommended filter efficiencies for

air systems serving specific nursing home areas, as well as recom-

mended minimum ventilation rates and desired pressure relation-

ships. Recommended interior winter design temperature is75°F for

areas occupied by patients and70°F for nonpatient areas. Provisions

for maintenance of minimum humidity levels in winter depend on

the severity of the climate and are best left to the designer’s judg-

ment. Where air conditioning is provided, the recommended inte-

rior summer design temperature and humidity is 75°F, and a

maximum of 60% rh.

The general design criteria in the hospital sections on Heating

and Hot Water Standby Service, Insulation, and Sustainability apply

to nursing home facilities as well.

STANDARDS

AENOR/UNE

Standard 100713:2005 Air Conditioning in Hospitals

ANSI/AAMI

Standard 58:2013 Chemical Sterilization and High-level Disinfection

in Health Care Facilities

ANSI/AIHA

Standard Z9.5-2012 Laboratory Ventilation

ANSI/ASHRAE

Standard 15-2013 Safety Code for Mechanical Refrigeration

52.2-2012 Method of Testing General Ventilation Air-

Cleaning Devices for Removal Efficiency by

Particle Size

62.1-2013 Ventilation for Acceptable Indoor Air Quality

ANSI/ASHRAE/IES

Standard 90.1-2013 Energy Standard for Buildings Except Low-Rise

Residential Buildings

ANSI/ASHRAE/ASHE

Standard 170-2017 Ventilation of Health Care Facilities

ANSI/ASHRAE/ACCA

Standard 180-2012 Standard Practice for Inspection and Maintenance

of Commercial Building HVAC Systems

ASHRAE

Standard 145.2-2016 Laboratory Test Method for Assessing the

Performance of Gas-Phase Air-cleaning

Systems: Air-cleaning Devices

188-2018 Building Water Systems

189.3-2017 Design, Construction, and Operation of Sustain-

able, High-Performance Health Care Facilities

Guideline 10-2011 Interactions Affecting the Achievement of

Acceptable Indoor Environments

12-2000 Minimizing the Risk of Legionellosis Associated

with Building Water Systems

26-2012 Guideline for Field Testing of General Ventilation

Filtration Devices and Systems for Removal

Efficiency in-situ by Particle Size and

Resistance to Airflow

29-2009 Guideline for the Risk Management of Public

Health and Safety in Buildings

ANSI/ASTM

Standard E84-2014 Standard Test Method for Surface Burning

Characteristics of Building Materials

ANSI/NFPA

Standard 45-2011 Standard on Fire Protection for Laboratories Using

Chemicals

90A-2015 Standard for the Installation of Air Conditioning

and Ventilation Systems

92A-2009 Recommended Practice for Smoke-Control

Systems

99-2012 Health Care Facilities Code

255-2006 Standard Method of Test of Surface Burning

Characteristics of Building Material

Code 101-2012 Life Safety Code

ANSI/NSF

Standard 49-2012 Biosafety Cabinetry: Design, Construction,

Performance, and Field Certification

ANSI/UL

Standard 181-2013 Factory-Made Air Ducts and Air Connectors, 10th

ed.

CAN/CSA

Standard Z317.2-15 Special Requirements for Heating, Ventilation, and

Air-Conditioning (HVAC) Systems in Health

Care Facilities

UK Department of Health and Social Care

Health Technical Specialized Ventilation for Healthcare Premises

Memoranda (HTM)

03-01

REFERENCES

ASHRAE members can access ASHRAE Journal articles and

ASHRAE research project final reports at technologyportal.ashrae

.org. Articles and reports are also available for purchase by nonmem-

bers in the online ASHRAE Bookstore at www.ashrae.org/bookstore.

ACGIH. 2013. Industrial ventilation: A manual of recommended practice

for design, 28th ed. American Conference of Governmental Industrial

Hygienists, Cincinnati, OH.

ASHE. 2011. The environment of care and health care-associated infec-

tions. American Society for Healthcare Engineering of the American

Hospital Association, Chicago. www.ashe.org/resources/management_

monographs/pdfs/mg2011memarzadeh.pdf.

ASHE/IFMA. 2000. O & M benchmarks for health care facilities. American

Society for Healthcare Engineering of the American Hospital Association,

Chicago, and International Facility Management Association, Houston.

ASHP. 2006. ASHP guidelines on handling hazardous drugs. American Jour-

nal of Health-System Pharmacy 63:1172-1193.

ASHRAE. 2009. Advanced energy design guide for small hospitals and

healthcare facilities.

ASHRAE. 2012. Advanced energy design guide for large hospitals: 50%

energy savings.

ASHRAE. 2013. HVAC design manual for hospitals and clinics, 2nd ed.

Atkinson, J., Y. Chartier, C.L. Pessoa-Silva, P. Jensen, Y. Li, and W.-H. Seto,

2009. Natural ventilation for infection control in health-care settings.

WHO Publications.

Health Care Facilities 9.19

Birgand, G., G. Toupet, S. Rukly, G. Antoniotti, M.N. Deschamps, D.

Lepelletier, C. Pornet, J.B. Stern, Y.M. Vandamme, N. van der Mee-

Marguet, J.F. Timsit, and J.C. Lucet. 2015. Air contamination for pre-

dicting wound contamination in clean surgery: A large multicenter study.

American Journal of Infection Control 1:43(5):516-521.

Belani, K.G., M. Albrecht, P.D. McGovern, M. Reed, and C. Nachtsheim.

2013. Patient warming excess heat: The effects on orthopedic operating.

Anesthesia and Analgesia 117(2):406-411.

Burch, G.E., and N.P. Pasquale. 1962. Hot climates, man and his heart. C.C.

Thomas, Springfield, IL.

CDC. 2003. Guidelines for environmental infection control in health-care

facilities. Morbidity and Mortality Weekly Report 52(RR-10). www.cdc

.gov/mmwr/pdf/rr/rr5210.pdf.

CDC. 2005. Guidelines for preventing the transmission of Mycobacterium

tuberculosis in health-care settings, 2005. Morbidity and Mortality Week-

ly Report (MMWR) 52(RR-10). www.cdc.gov/mmwr/pdf/rr/rr5210.pdf/.

CETA. 2006. Compounding isolator testing guide CAG-002-2006. Con-

trolled Environment Testing Association (CETA), Raleigh, NC.

Chaddock, J.B. 1983. Ventilation and exhaust requirements for hospitals.

(RP-312). ASHRAE Research Project. Final Report.

Degenhardt, R.A., and J.F. Pfost. 1983. Fume hood design and application

for medical facilities. ASHRAE Transactions 89(2B):558-570.

DeRoos, R.L., R.S. Banks, D. Rainer, J.L. Anderson, and G.S. Michaelsen.

1978. Hospital ventilation standards and energy conservation: A sum-

mary of the literature with conclusions and recommendations (FY 78).

(LBNL paper LBL-8316), Final report.

Dettenkofer, M., M. Scherrer, V. Hoch, G. Schwarzer, J. Zentner, and E.D.

Daschner. 2003. Shutting down operating theater ventilation when the

theater is not in use: Infection control and environmental aspects. Infec-

tion Control and Hospital Epidemiology 24(8):596-600.

DIN. 2008. Ventilation and air conditioning—Part 4: VAC systems in build-

ings and rooms used in the health care sector. DIN Standard 1946-4.

Earnest, R., and W. Loesche. 1991. Measuring harmful levels of bacteria in

dental aerosols. Journal of the American Dental Association 122:55-57.

Eurovent/CECOMAF. 2005. Recommendation concerning calculating the

life cycle cost for air filters. European Committee of Air Handling, Air

Conditioning and Refrigeration Equipment Manufacturers, Paris. www

.eurovent-association.eu/fic_bdd/pdf_en_fichier/REC10_127727917

70.pdf.

FGI. 2014a. Guidelines for design and construction of hospitals and outpa-

tient facilities. Facilities Guidelines Institute, Dallas.

FGI. 2014b. Guidelines for design and construction of residential health,

care, and support facilities. Facilities Guidelines Institute, Dallas.

Greene, V.W., R.G. Bond, and M.S. Michaelsen. 1960. Air handling systems

must be planned to reduce the spread of infection. Modern Hospital

(August).

Gressel, M.G., and R.T. Hughes. 1992. Effective local exhaust ventilation

for controlling formaldehyde exposures during embalming. Applied

Occupational and Environmental Hygiene 7(12):840-845.

HAAD. 2014. Health facility guidelines. Department of Health–Abu Dhabi

(HAAD).

Hagopian, J.H., and E.R. Hoyle. 1984. Control of hazardous gases and

vapors in selected hospital laboratories. ASHRAE Transactions 90(2A):

341-353.

ISO. 2013. Field testing of general ventilation filtration devices and systems

for in situ removal efficiency by particle size and resistance to airflow.

Standard 29462:2013.

Jackson, C. 1996. Humidification in the upper respiratory tract: a physiolog-

ical overview. Intensive and Critical Care Nursing 12(1):27-32.

Jacob, J.T., A. Kasali, J.P. Steinberg, C. Zimring, and M.E. Denham. 2013.

The role of the hospital environment in preventing healthcare-associated

infections caused by pathogens transmitted through the air. HERD 7:74-

98.

Johnson, D.L., K.R. Mead, R.A. Lynch, and D.V.L. Hirst. 2013. Lifting the

lid on toilet plume aerosol: A literature review with suggestions for

future research. American Journal of Infection Control 41(3):254-258.

Koenigshofer, D., R. Guevara, D. Koenigshofer, and D. Nemecek. 2009.

Method of testing and reporting of energy use by medical equipment.

ASHRAE Research Project RP-1343, Final Report.

Lewis, J.R. 1988. Application of VAV, DDC, and smoke management to

hospital nursing wards. ASHRAE Transactions 94(1):1193-1208.

Li, Y., G.M. Leung, J.W. Tang, X. Yang, C.Y. Chao, J.Z. Lin, J.W. Lu, P.V.

Nielsen, J. Niu, H. Qian, A.C. Sleigh, H.J. Su, J. Sundell, T.W. Wong, and

P.L. Yuen. 2007. Role of ventilation in airborne transmission of infec-

tious agents in the built environment—A multi-disciplinary systematic

review. Indoor Air 17(1):2-18.

Liljedahl, S.-O., L.-O. Lamke, C.-E. Jonsson, H. Nordström, and B. Nylén.

1979. Warm dry air treatment of 345 patients with burns exceeding 20

per cent of the body surface. Scandinavian Journal of Plastic and Recon-

structive Surgery 13(1):205.

Love, C. 2011. Operating room HVAC setback strategies. ASHE Mono-

graph. American Society for Healthcare Engineering (ASHE), Chicago.

Memarzedeh, F. 2013. Literature review: Room ventilation and airborne dis-

ease transmission. ASHE Monograph. American Society for Healthcare

Engineering (ASHE), Chicago.

Memarzadeh, F., and A. Manning. 2002. Comparison of operating room

ventilation systems in the protection of the surgical site. ASHRAE Trans-

actions 108(2).

Memarzadeh, F., and W. Xu. 2012. Role of air changes per hour (ACH) in

possible transmission of airborne infections. Building Simulation 5(1):

15-28.

Murray, W.A., A.J. Streifel, T.J. O’Dea, and F.S. Rhame. 1988. Ventilation

protection of immune compromised patients. ASHRAE Transactions

94(1):1185-1192.

NFPA. 2018. Life safety code. Code 101. National Fire Protection Associa-

tion, Quincy, MA.

Ninomura, P.T., and G. Byrns. 1998. Dental ventilation theory and applica-

tions.

ASHRAE Journal 40(2):48-52.

NIOSH. 2003. Guidance for filtration and air-cleaning systems to protect

building environments from airborne chemical, biological, or radiologi-

cal attacks. DHHS (NIOSH) Publication 2003-136. National Institute

for Occupational Safety and Health (NIOSH).

NIOSH. 2004. Preventing occupational exposure to antineoplastic and other

hazardous drugs in health care settings. DHHS (NIOSH) Publication

2004-165. Department of Health and Human Services and National Insti-

tute for Occupational Safety and Health, Cincinnati, OH.

NIOSH. 2009. Environmental control for tuberculosis: Basic upper-room

ultraviolet germicidal irradiation guidelines for healthcare settings.

DHHS (NIOSH) Publication 2009-105. National Institute for Occupa-

tional Safety and Health (NIOSH).

NRC. 1980. Regulatory guide 10.8. Nuclear Regulatory Commission.

OSHA. [Annual] Occupational exposure to ethylene oxide. OSHA 29 CFR,

Part 1910.1047. U.S. Department of Labor, Washington, D.C.

Patberg, W.R., and J.J. Rasker. 2004. Weather effects in rheumatoid arthritis:

From controversy to consensus: A review. The Journal of Rheumatology

31(7):1327-34.

Pearce, E.N. 2006. Diagnosis and management of thyrotoxicosis. The BMJ

10; 332(7554):1369-1373.

Pfost, J.F. 1981. A re-evaluation of laminar air flow in hospital operating

rooms. ASHRAE Transactions 87(2):729-739.

Richard, L., T. Kosatsky, and A. Renouf. 2011. Correlates of hot day air-con-

ditioning use among middle-aged and older adults with chronic heart and

lung diseases: The role of health beliefs and cues to action. Health Edu-

cation Research 26(1):77-88.

Rousseau, C.P., and W.W. Rhodes. 1993. HVAC system provisions to mini-

mize the spread of tuberculosis bacteria. ASHRAE Transactions 99(2):

1201-1204.

Samuals, T.M., and M. Eastin. 1980. ETO exposure can be reduced by air

systems. Hospitals 54(13):66-68.

Short, C.A., and S. Al-Maiyah. 2009. Design strategy for low energy venti-

lation and cooling of hospitals. Building Research & Information

37(3):264-292.

Setty, B.V.G. 1976. Solar heat pump integrated heat recovery. Heating, Pip-

ing and Air Conditioning (July).

Smith, P.W., et al. 2006. Designing a biocontainment unit to care for patients

with serious communicable diseases: A consensus statement. Biosecu-

rity and Bioterrorism: Biodefense Strategy, Practice, and Science 4(4):

351-365.

Turpin, J. 2013. ASHRAE manual focuses on hospital design. ACHR News

(November). www.achrnews.com/articles/124673-ashrae-manual-focus

-hospital-design.

USP. 2008. National formulary, 31st ed., Ch. 797: Pharmaceutical com-

pounding—Sterile preparations. United States Pharmacopeial Conven-

tion, Rockville, MD.

9.20 2019 ASHRAE Handbook—HVAC Applications

USP. 2016. Hazardous drugs—Handling in healthcare settings. Ch. 800

in The United States Pharmacopeia, first supplement to 39th revision.

United States Pharmacopeial Convention, Rockville, MD. www.usp.org

/compounding/general-chapter-hazardous-drugs-handling-healthcare.

Walker, J.E.C., and R.E. Wells. 1961. Heat and water exchange in the respi-

ratory tract. American Journal of Medicine (February):259.

Wells, W.F. 1934. On airborne infection. Study II: Droplets and droplet

nuclei. American Journal of Hygiene 20:611.

WHO. 2009. Natural ventilation for infection control in health-care settings.

World Health Organization (WHO).

Zhou, Y.P., Z.H. Zhou, W.M. Zhou, J.L. Ren, Y.H. Wu, X.Z. Rong, and

L. Lang. 1998. Successful recovery of 14 patients afflicted with full-

thickness burns for more than 70 per cent body surface area. Burns

24(2):162-165.

BIBLIOGRAPHY

ACS. 2000. Guidelines for optimal ambulatory surgical care and office-

based surgery, 3rd ed. American College of Surgeons, Chicago.

AIA. 2006. Guidelines for design and construction of hospital and health

care facilities. The American Institute of Architects, Washington, D.C.

Demling, R.H., and J. Maly. 1989. The treatment of burn patients in a lam-

inar flow environment. Annals of the New York Academy of Sciences

353:294-259.

DHHS. 1984. Energy considerations for hospital construction and equipment:

An addendum to guidelines for construction and equipment of hospital

and medical facilities. Publication HRS-M-HF, 84-1A. U.S Department

of Health and Human Services, Washington, D.C.

DHHS. 1984. Guidelines for construction and equipment of hospital and

medical facilities. Publication HRS-M-HF, 84-1. U.S. Department of

Health and Human Services, Washington, D.C.

Fitzgerald, R.H. 1989. Reduction of deep sepsis following total hip arthro-

plasty. Annals of the New York Academy of Sciences 353:262-269.

Gustofson, T.L., G.B. Lavely, E.R. Brawner, Jr., R.H. Hutcheson, Jr., P.F.

Wright, and W. Schaffner. 1982. An outbreak of airborne nosocomial

Varicella. Pediatrics 70(4):550-556.

Luciano, J.R. 1984. New concept in French hospital operating room HVAC

systems. ASHRAE Journal 26(2):30-34.

Michaelson, G.S., D. Vesley, and M.M. Halbert. 1966. The laminar air flow

concept for the care of low resistance hospital patients. Paper presented

at the annual meeting of American Public Health Association, San Fran-

cisco (November).

NIOSH. 1996. Control of nitrous oxide in dental operatories. NIOSH Crite-

ria Document 96-107 (January). National Institute for Occupational

Safety and Health, Cincinnati, OH.

NIOSH. 1975. Development and evaluation of methods for the elimination

of waste anaesthetic gases and vapors in hospitals. NIOSH Criteria Doc-

ument 75-137. National Institute for Occupational Safety and Health,

Cincinnati, OH.

Rhodes, W.W. 1988. Control of microbioaerosol contamination in critical

areas in the hospital environment. ASHRAE Transactions 94(1):1171-

1184.

Woods, J.E., D.T. Braymen, R.W. Rasussen, G.L. Reynolds, and G.M. Mon-

tag. 1986. Ventilation requirement in hospital operating rooms—Part I:

Control of airborne particles. ASHRAE Transactions 92(2A):396-426.