HVAC Design Manual for Hospitals and Clinics

246 Pages·7.571 MB·246\246

by  ASHRAE Technical Committee

HVAC Design Manual
for

Hospitals Clinics
and

Second Edition
© 2003, 2013 ASHRAE
1791 Tullie Circle
Atlanta, GA 30329
All rights reserved.
Printed in the United States of America.
ISBN 978-1-936504-39-8
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of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
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Library of Congress Catalog-in-Publication Data
HVAC design manual for hospitals and clinics. – Second edition.
Summary: “Provides in-depth design recommendations and proven, cost effective, and reliable solutions for health care
HVAC design that provide low maintenance cost and high reliability based on best practices from consulting and hospital
engineers with decades of experience in the design, construction, and operation of health care facilities” – Provided by publisher.
pages cm
Includes bibliographical references and index.
ISBN 978-1-936504-39-8 (hardcover : alk. paper)
1. Hospital buildings–United States–Design and construction–Handbooks, manuals, etc. 2. Clinics–United States–Design and
construction–Handbooks, manuals, etc. 3. Hospital buildings–Heating and ventilation–United States–Handbooks, manuals, etc.
4. Clinics–Heating and ventilation–United States–Handbooks, manuals, etc. 5. Hospital buildings–Air conditioning–United
States–Handbooks, manuals, etc. 6. Clinics–Air conditioning–United States–Handbooks, manuals, etc. I. American Society
of Heating, Refrigerating and Air-Conditioning Engineers. II. Title: heating, ventilation, and air conditioning design manual for
hospitals and clinics.
RA967.H85 2012
725'.51–dc23 2012049776
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CONTENTS
FOREWORD .....................................................................IX
CHAPTER 1 – OVERVIEW OF HEALTH CARE HVAC SYSTEMS .........................1
1.1 Introduction ................................................................... 1
1.2 (cid:37)(cid:68)(cid:86)(cid:76)(cid:70)(cid:3)(cid:38)(cid:79)(cid:68)(cid:86)(cid:86)(cid:76)(cid:191)(cid:70)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:3)(cid:82)(cid:73)(cid:3)(cid:43)(cid:72)(cid:68)(cid:79)(cid:87)(cid:75)(cid:3)(cid:38)(cid:68)(cid:85)(cid:72)(cid:3)(cid:41)acilities ......................................... 1
1.3 Health Care HVAC(cid:3)(cid:54)(cid:92)(cid:86)(cid:87)(cid:72)(cid:80)(cid:3)(cid:41)(cid:88)(cid:81)(cid:70)(cid:87)(cid:76)(cid:82)(cid:81)(cid:86)(cid:3) .............................................. 2
1.4 Criteria and Accreditation ........................................................ 5
1.5 Sustainable Design ............................................................. 7
1.6 Equipment Sizing for Heating and Cooling Loads ..................................... 9
1.7 Ventilation and Outdoor Air Quality ............................................... 10
1.8 Environmental Control ......................................................... 12
1.9 HVAC System Hygiene ......................................................... 13
1.10 (cid:41)(cid:79)(cid:72)(cid:91)(cid:76)(cid:69)(cid:76)(cid:79)(cid:76)(cid:87)(cid:92)(cid:3)(cid:73)(cid:82)(cid:85)(cid:3)(cid:41)(cid:88)(cid:87)(cid:88)(cid:85)(cid:72)(cid:3)(cid:38)(cid:75)(cid:68)(cid:81)(cid:74)(cid:72)(cid:86) ................................................... 14
1.11 Integrated Design ............................................................. 14
1.12 Commissioning .............................................................. 17
1.13 Conclusions .................................................................. 18
References ....................................................................... 18
CHAPTER 2 – INFECTION CONTROL ...............................................19
2.1 Introduction .................................................................. 19
2.2 Role of HVAC Systems in Infection Control ........................................ 20
2.3 How the Human Body is Affected by Airborne Contaminants ........................... 21
2.4 Risk Management Approach to Infection Control .................................... 25
2.5 Surgical Site Infections ......................................................... 26
2.6 Protecting Populations ......................................................... 27
2.7 Air Change Rate/Dilution ....................................................... 27
2.8 NaturalVentilation ............................................................ 28
2.9 (cid:41)iltration .................................................................... 29
2.10 Humidity .................................................................... 30
2.11 Ultraviolet Radiation ........................................................... 31
2.12 Air Movement and Pressurization ................................................. 32
2.13 Effect of Infection Control on HVAC Design ....................................... 33
References ....................................................................... 34
CHAPTER 3 – AIR-HANDLING AND DISTRIBUTION SYSTEMS ........................35
3.1 Introduction .................................................................. 35
3.2 Concept Design ............................................................... 35
3.3 Air-Handling Unit Component Design Considerations ................................ 42
3.4 Air Distribution System Alternatives .............................................. 66
3.5 Ductwork .................................................................... 70
3.6 Terminal Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.7 RoomAir Distribution ......................................................... 76
3.8 (cid:39)(cid:72)(cid:75)(cid:88)(cid:80)(cid:76)(cid:71)(cid:76)(cid:191)(cid:70)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81) .............................................................. 83
References ....................................................................... 89
v
vi HVAC DESIGN MANUAL FOR HOSPITALS AND CLINICS
CHAPTER 4 – UTILITIES ..........................................................91
4.1 Introduction .................................................................. 91
4.2 General Considerations ......................................................... 91
4.3 Central Cooling Plants ......................................................... 96
4.4 Central Heating Plants ........................................................ 104
4.5 Other Utilities ............................................................... 110
References ...................................................................... 111
Bibliography ..................................................................... 111
CHAPTER 5 – LIFE SAFETY ......................................................113
5.1 Health Care Occupancy Life Safety ............................................. 113
5.2 Establishment of Criteria ..................................................... 113
5.3 Key Elements of Life Safety ................................................... 114
References ...................................................................... 122
CHAPTER 6 – CONTROLS AND INSTRUMENTATION ................................123
6.1 Introduction ................................................................. 123
6.2 Characteristics of Control Systems ............................................... 123
6.3 Room Pressurization Controls .................................................. 126
6.4 Operating Room Controls ...................................................... 128
References ...................................................................... 131
CHAPTER 7 – EXISTING FACILITIES ..............................................133
7.1 Overview ................................................................... 133
7.2 (cid:41)acility Assessment ((cid:41)(cid:36)) ....................................................... 133
7.3 Design Considerations for Renovation Projects ..................................... 143
7.4 (cid:38)(cid:82)(cid:81)(cid:87)(cid:85)(cid:68)(cid:70)(cid:87)(cid:82)(cid:85)(cid:3)(cid:52)(cid:88)(cid:68)(cid:79)(cid:76)(cid:191)(cid:70)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:86) ...................................................... 149
References ...................................................................... 149
Bibliography ..................................................................... 150
CHAPTER 8 – ROOM DESIGN ....................................................151
8.1 Introduction to Room Design . .................................................. 151
8.2 Room Pressurization ......................................................... 151
8.3 Operating Rooms ............................................................ 154
8.4 Imaging Rooms ............................................................. 164
8.5 Laboratories ................................................................ 173
8.6 Pharmacies ................................................................. 178
8.7 Morgue and Autopsy ......................................................... 184
8.8 Isolation Rooms ............................................................. 185
8.9 Central Sterile ............................................................... 190
8.10 Renal Dialysis and Chemotherapy Infusion ........................................ 191
8.11 ICU ....................................................................... 191
8.12 Postanesthesia Care Unit (Recovery) ............................................. 192
8.13 Emergency Departments ....................................................... 193
8.14 Burn Units ................................................................. 194
8.15 Bone Marrow Transplant ...................................................... 194
8.16 Psychiatric .................................................................. 195
8.17 Procedure Rooms ............................................................ 195
8.18 Outpatient/Ambulatory Care .................................................... 196
8.19 Data Centers ................................................................ 200
References ...................................................................... 201
CONTENTS vii
CHAPTER 9 – BUSINESS OF HEALTH CARE .......................................203
9.1 Introduction ................................................................ 203
9.2 (cid:43)(cid:72)(cid:68)(cid:79)(cid:87)(cid:75)(cid:3)(cid:38)(cid:68)(cid:85)(cid:72)(cid:3)(cid:41)(cid:68)(cid:70)(cid:76)(cid:79)(cid:76)(cid:87)(cid:92)(cid:3)(cid:38)(cid:79)(cid:68)(cid:86)(cid:86)(cid:76)(cid:191)(cid:70)(cid:68)(cid:87)(cid:76)(cid:82)(cid:81)(cid:86) .............................................. 203
9.3 Demand, Drivers, and Trends for Health Care ...................................... 206
9.4 Evidence-Based Design ....................................................... 208
References ...................................................................... 209
CHAPTER 10 – DISASTER PLANNING AND EMERGENCY MANAGEMENT ............211
10.1 Introduction ................................................................. 211
10.2 Disaster Planning ............................................................ 214
10.3 Emergency Management ....................................................... 214
10.4 Disaster Preparedness ........................................................ 215
10.5 (cid:41)acility Needs for Disaster Planning and Emergency Management ...................... 217
10.6 Power ...................................................................... 220
References ...................................................................... 225
CHAPTER 11 – OPERATIONS AND MAINTENANCE .................................227
11.1 Introduction ................................................................. 227
11.2 Regulatory Considerations ..................................................... 228
11.3 Risk Assessments ............................................................ 231
11.4 Operations .................................................................. 236
11.5 Maintenance ................................................................ 242
11.6 (cid:41)ire and Smoke Dampers ...................................................... 245
References ...................................................................... 246
CHAPTER 12 – SUSTAINABILITY IN HEALTH CARE FACILITIES ......................249
12.1 Introduction ................................................................. 249
12.2 SustainabilityTrends and Economic Considerations ................................. 250
12.3 Energy Benchmarking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
12.4 Commissioning .............................................................. 256
12.5 Energy Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
12.6 Ener(cid:74)(cid:92)(cid:3)(cid:40)(cid:73)(cid:191)(cid:70)(cid:76)(cid:72)(cid:81)(cid:70)(cid:92) ............................................................ 259
12.7 (cid:41)(cid:76)(cid:81)(cid:68)(cid:81)(cid:70)(cid:76)(cid:68)(cid:79)(cid:3)(cid:44)(cid:81)(cid:70)(cid:72)(cid:81)(cid:87)(cid:76)(cid:89)(cid:72)(cid:86)(cid:3)(cid:73)(cid:82)(cid:85)(cid:3)(cid:40)(cid:81)(cid:72)(cid:85)(cid:74)(cid:92)(cid:3)(cid:40)(cid:73)(cid:191)(cid:70)(cid:76)(cid:72)(cid:81)(cid:70)(cid:92) ......................................... 260
12.8 Indoor Environmental Quality .................................................. 261
12.9 W(cid:68)(cid:87)(cid:72)(cid:85)(cid:3)(cid:56)(cid:86)(cid:72)(cid:3)(cid:40)(cid:73)(cid:191)(cid:70)(cid:76)(cid:72)(cid:81)(cid:70)(cid:92) ......................................................... 276
12.10Site Sustainability ............................................................ 277
References ...................................................................... 278
CHAPTER 13 – SEISMIC RESTRAINTS IN HEALTH CARE HVAC DESIGN .............281
13.1 Introduction ................................................................. 281
13.2 Seismic Restraints for Nonstructural Components ................................... 282
13.3 Seismic Design and Risk Categories ............................................. 282
13.4 Component Impor(cid:87)(cid:68)(cid:81)(cid:70)(cid:72)(cid:3)(cid:41)(cid:68)(cid:70)(cid:87)(cid:82)(cid:85) .................................................. 283
13.5 Seismic Design Requirements .................................................. 285
13.6 Seismic Restraint Special Inspections and Tests ..................................... 288
References ...................................................................... 290
ACRONYMS ....................................................................291
GLOSSARY .....................................................................293
INDEX .........................................................................299
CHAPTER 1
OVERVIEW OF HEALTH CARE
HVAC SYSTEMS
HVAC systems in health care facilities provide a broad range of 1.1 INTRODUCTION
services in support of populations who are uniquely vulnerable to an
elevated risk of health, fire, and safety hazard. These heavily regulated,
high-stakes facilities undergo continuous maintenance, verification,
inspection, and recertification; typically operate 24 hours/day, 7 days/
week; and are owner-occupied for long life cycles. Health care HVAC
systems must be installed, operated, and maintained in spatial and
functional conjunction with a host of other essential building services,
including emergency and normal power, plumbing and medical-gas
systems, automatic transport, fire protection, and myriad IT systems,
all within a constrained building envelope. Health care facilities and
services are characterized by high rates of modification because of the
continuously evolving science and economics of health care, and
consume large quantities of energy and potable water. The often unique
environmental conditions associated with these facilities, and the
critical performance, reliability, and maintainability of the HVAC
systems necessary to their success, demand a specialized set of
engineering practices and design criteria established by model codes
and standards and enforced by authorities having jurisdiction.
Health care facilities vary widely in the nature and complexity of 1.2 BASIC CLASSIFICATION
services they provide and the relative degree of illness or injury of the OF HEALTH CARE
patients treated—from a neighborhood general practitioner’s office to FACILITIES
large regional or university medical centers and specialty hospitals.
Facilities in the health care category can include, in addition to the
practitioner’s office, neighborhood clinics, mental wellness centers,
birthing centers, imaging facilities, hospice care, and long-term nursing
care, among others. As a rule, environmental control requirements and
1
2 HVAC DESIGN MANUAL FOR HOSPITALS AND CLINICS
the role of the HVAC system in life safety and infection control become
more important with increasing complexity of the medical services
provided and the acuity of illness of the patient population. This manual
is primarily intended to address HVAC systems for inpatient hospitals,
except where otherwise indicated.
1.3 HEALTH CARE HVAC In support of the health care process, HVAC systems are called
SYSTEM FUNCTIONS upon to perform several vital functions that affect environmental
conditions, infection and hazard control, and building life safety. Staff
and patient comfort, and the provision of therapeutic space conditions,
facilitate optimum patient treatment outcomes. Environmental
conditioning for electronic data storage, supporting IT systems, and
special imaging and other medical equipment is critical to the operation
of these essential services. Through containment, dilution, and removal
of pathogens and toxins, the HVAC system is a key component of
facility safety and infection control. In inpatient and many ambulatory
treatment facilities, the inability (or reduced ability) of patients to
respond properly to fire emergencies requires the HVAC system to
support vital smoke exhaust and building compartmentation features
of the life safety system. Finally, the HVAC system should interact
with the architectural building envelope to control the entry of
unconditioned air, together with outdoor contaminants and moisture.
1.3.1 Comfort Conditioning Across the range of health care facilities, health care practices
often expose patients and staff to conditions that dictate unique
environmental requirements. As in any facility, the comfort of building
occupants is fundamental to overall well-being and productivity. In the
health care facility, a comfortable environment has a significant role in
facilitating healing and recovery. A sick or injured patient in an
uncomfortable environment is subject to thermal stress that may hinder
the body’s ability to properly regulate body heat, interfere with rest,
and be psychologically harmful. At the same time, a health care
provider stressed by an uncomfortable environment may not function
at peak performance levels. Patients clothed in a simple gown in an
examination room, for example, or orthopedic surgical staff heavily
garbed in scrub suits during an hours-long, complex, and stressful
procedure, require special room temperature and humidity levels and
controls. Similarly, room airflow patterns and air change rates influence
thermal comfort. For these reasons, health care codes and criteria
establish specific requirements for space temperature, relative
humidity, and total air change rates.
1.3.2 Therapeutic Certain medical functions, treatments, or healing processes
Conditioning demand controlled environmental temperature and/or relative humidity
conditions that deviate from the requirements for personal comfort.
Operating rooms and nursery units, for example, often require a
range of room temperatures spanning several degrees, regardless of
the season, to best facilitate a given procedure or patient condition.
Burn-patient treatment rooms and bedrooms may require elevated
temperature and relative humidity (RH) conditions (up to 100°F
OVERVIEW OF HEALTH CARE HVAC SYSTEMS 3
[37.7°C] and 35% to 40% rh, according to DOD [2011]). Some clinicians
desire the ability to reset emergency department room temperatures to
as high as 90°F [32.2°C] for treatment of hypothermia cases. Criteria
call for long-term in-patient spaces to be humidified to minimum
levels to avoid the dry skin and mucous membranes associated with
very low RH levels that add to discomfort and possibly impede
respiratory immune function. As of the date of this publication,
however, there is no scientific evidence to firmly establish that extended
exposure to very low humidity contributes to poorer patient outcomes.
With few exceptions (such as free-standing behavioral health, 1.3.3 Infection Control
sports medicine, or maternity care centers), medical facilities are
places where relatively high levels of pathogenic (disease-causing)
microorganisms are generated and concentrated by an infected patient
population or by procedures that handle or manipulate infected human
tissues and bodily fluids. These pathogens are spread by a number of
contact and, to a lesser extent, noncontact (airborne) causes, which are
dealt with in detail in Chapter 2. To some degree, the entire building
population is at elevated risk of exposure to these pathogens. Sick and
injured patients, having suppressed or compromised immune function,
are highly susceptible to new infections. Visitors often accompany
sick or injured friends or loved ones to high-exposure areas such as
clinical waiting rooms and emergency departments. By the nature of
their profession, health care staff work in proximity to infectious
agents on a daily basis. Health care facilities therefore require stringent
operational practices and engineering controls to safeguard the
building population. The HVAC system is one of several tools and
processes used in the control of infection.
Many medical facilities include functions or processes in which 1.3.4 Ventilation and
chemical fumes, aerosols, or harmful gases are stored and generated, Environmental Control
posing health or safety hazards. Examples include laboratories where for Special Functions
aerosolizing chemicals are used to fix slide specimens, preserve
tissues, or perform other processes; orthopedic appliance and artificial
limb shops involving adhesives and other aerosolizing agents; and
anesthetizing locations, in which long-term exposure to even trace
concentrations of anesthetizing gases can have harmful consequences.
In such applications, HVAC equipment operates in conjunction with
primary containment equipment, such as fume hoods, radioisotope
hoods, laminar flow benches, and waste anesthesia evacuation
systems, to contain and exhaust these contaminants or dilute them to
safe levels.
In other health care applications, the HVAC system is called upon
to assist in the maintenance of a sterile environment for products or
procedures that must be protected from environmental contamination.
Laboratory culturing procedures, and certain pharmaceutical handling
and compounding procedures, are examples where the HVAC system
functions in conjunction with containment equipment to protect
the product.
4 HVAC DESIGN MANUAL FOR HOSPITALS AND CLINICS
1.3.5 Life Safety In facilities classified as Health Care or Ambulatory Health Care
by NFPA 101: Life Safety Code® (NFPA 2012) from the National Fire
Protection Association or Type I-2 by the International Building Code®
(IBC®)(ICC 2012), HVAC systems are required to support special
building compartmentation, opening protection, smoke control, and
detection systems providing for the “defend in place” concept of life
safety. Containment is facilitated by the application of smoke and fire
dampers and, in some cases, by restricting HVAC system cross-over
between smoke zones. HVAC systems contribute to the detection and
containment of fire and smoke and may be called upon to evacuate or
exclude smoke from atria or exit enclosures. Engineeredsmoke control
systems may be required to provide complex zoned pressurization
control. More detailed information on HVAC applications and building
life safety is provided in Chapter 5.
1.3.6 Role of the The integrity of the building envelope is essential to minimize the
Building Envelope introduction of unconditioned, unfiltered air into a building, as well as to
effectively exclude moisture. Condensation of humid outdoor air within
building envelope assemblies is conducive to mold colonization, which,
in addition to causing expensive material damage, poses a risk of deadly
infection from Aspergillus and other so-called opportunistic mold
genera. No envelope is perfect, and abundant evidence shows that even
well-designed and constructed envelopes allow some degree of
infiltration from building pressurization differentials caused by wind,
stack effect, and operation of the HVAC system. Generally, with the
exception of very cold climates where neutral pressurization may be
called for, it is desirable to positively pressurize the building interior to
minimize infiltration. Some HVAC designs approach controlled,
continuous, positive pressurization by maintaining a controlled offset
between outdoor ventilation air and exhaust. These systems are simple
and reliable. More complex pressure-control approaches are now being
suggested by some design engineers. HVAC designers should be aware,
and make the building architect aware, that the deliberate depressurization
of spaces on the building perimeter, including disease isolation rooms
and patient toilets, and the depressurization of plenums and exterior wall
cavities by plenum return systems, poorly balanced ducted return
systems, and central exhaust systems can exacerbate the passage of
moisture and unconditioned, unfiltered air across the building envelope
in those locations.
1.3.7 Patient Privacy The need to prevent room-to-room transmission of private patient
conversations is addressed by codes and standards and by the Health
Care Information Portability and Accountability Act (HIPAA). Codes
and standards provide minimum sound transmission class (STC), or
other acoustical performance criteria, for the architectural enclosure
elements of critical spaces such as provider office and exam rooms,
and may address recommendations for background noise, and for
minimizing sound transmission through connecting ductwork. Transfer
air ductwork and common plenum returns for such spaces require
special consideration and treatment, such as built-in attenuating
OVERVIEW OF HEALTH CARE HVAC SYSTEMS 5
features, to minimize “crosstalk.” Even with fully ducted returns,
consideration must be given to the attenuating qualities (chiefly the
extent and configuration of layout and fittings) of interconnecting
ductwork. Although a great deal of attention is normally focused on
minimizing HVAC background noise, some degree of “white noise”
from HVAC systems helps to minimize conversation intelligibility.
One of the HVAC designer’s first tasks is to establish the project 1.4 CRITERIA AND
design criteria. Most state and federal government agencies, and many ACCREDITATION
local governments, establish criteria for the design of health care
1.4.1 Design Criteria
facilities within their jurisdictions. A jurisdiction may utilize its own
criteria and codes or cite model, national, or international building
codes or design standards. Some private health care institutions and
corporations also establish their own design criteria that go beyond
jurisdictional requirements. Frequently adopted or cited codes,
standards, and design guidelines relating to health care facility HVAC
systems include the following:
• Guidelines for Design and Construction of Hospital and Health
Care Facilities (known as the “FGI Guidelines”), 2010, The
Facility Guidelines Institute (FGI)
• ANSI/ASHRAE/ASHE Standard 170-2008, Ventilation of Health
Care Facilities
• ANSI/ASHRAE/IES Standard 90.1-2010, Energy Standard for
Buildings Except Low-Rise Residential Buildings
• (Proposed) ASHRAE Standard 189.3P, Design, Construction
and Operation of Sustainable High Performance Health Care
Facilities (under development as of date of this publication)
• HVAC Design Manual for New, Replacement, Addition, and
Renovation of Existing VA Facilities, 2011, U.S. Department
of Veteran Affairs
• The Joint Commission, Environment of Care standards
• National Fire Protection Association (NFPA) standards
• IndustrialVentilation, 2004, American Conference of
Governmental Industrial Hygienists (ACGIH)
• Centers for Disease Control and Prevention (CDC) guidelines
and recommended practices
• Model building and mechanical codes, including the
International Building Code (IBC),International Energy Code,
andInternational Mechanical Code
• Leadership in Energy and Environmental Design (LEED®) for
HealthcareTM
• Unified Facilities Criteria (UFC) Manual 4-510-01, U.S.
Department of Defense
• CAN/CSA Z317.2-10, Special Requirements for Heating,
Ventilation, and Air Conditioning (HVAC) Systems in Health
Care Facilities
• United States Pharmacopoeia Chapter 797