Table Of ContentThis file is licensed to john Smith ([email protected]). Publication Date: 6/1/2016
CONTRIBUTORS
In addition to the Technical Committees, the following individuals contributed significantly
to this volume. The appropriate chapter numbers follow each contributor’s name.
Howard McKew (1, 5) Mick Schwedler (13, 14) Joseph Brooks (21)
BuildingSmartSoftware, LLC The Trane Company AMCA International
Steven Nicklas (2) Forrest B. Fencl (17) Patrick Chinoda (21)
UV Resources Revcor, Inc.
Gene Strehlow (2)
Jaak Geboers (17) Armin Hauer (21, 45)
Stephen W. Duda (3)
Philips Lighting BV ebm-papst, Inc.
Ross & Baruzzini, Inc.
Stephen B. Martin, Jr. (17) Zhiping Wang (21)
R. Dan Leath (3)
Murphy Company Centers for Disease Control/National Morrison Products, Inc.
Institute for Occupational Safety and
Rachel Romero (4) Gary Berlin (22)
Health
National Renewable Energy Laboratory Humidity Consulting LLC
Dean A. Saputa (17)
Lynn Werman (4) Sukru Erisgen (22)
UV Resources
DriSteem Corporation
Dove Feng (6)
Richard L. Vincent (17)
Taylor Engineering Nicholas Lea (22)
Icahn School of Medicine at Mount Sinai
Nortec Humidity Ltd.
nc. Ryan MacGillivray (6) David L. Witham (17)
E, I Daniels Wingerak Engineering Ltd. UltraViolet Devices, Inc. WIinlgliearmso lFl oRxa (n2d3/T, 2ra7n, e39)
A Paul Raftery (6)
R William Artis (18)
H University of California, Berkeley Steve Brickley (24)
S Daikin Applied N.Y.
A Munters Corporation
6 Peter Simmonds (6) Brian Bogdan (18)
201 Building and System Analytics LG Electronics Phillip Farese (24)
© Gearoid Foley (7) Advantix Systems
er. Integrated CHP Systems Yvette Daniel (18) Michael Sherber (24)
s Mitsubishi Electric USA, Inc.
u PPL SavageALERT
gle Lucas B. Hyman (7, 12, 51) Paul Doppel (18) Richard Wolcott (24)
n Birol I. Kilkis (7) Mitsubishi Electric USA, Inc.
si
or Baskent University Dermot McMorrow (18) Ralph Kittler (25)
ed f John S. Andrepont (8, 51) Mitsubishi Electric Canada Seresco Technologies, Inc.
ns The Cool Solutions Company Alois Malik (25)
e Douglas Tucker (18)
Lic Dharam Punwani (7, 8) Mitsubishi Electric USA, Inc. Dectron International, Inc.
Avalon Consulting, Inc. Harry Milliken (25)
Herman Behls (19)
Chris Gray (9) Desert-Aire Corporation
Ralph Koerber (19)
Southern Company Prakash Dhamshala (26)
ATCO Rubber Products
Gary Phetteplace (9, 12) University of Tennessee
GWA Research Craig Wray (19, 21) Gursaran D. Mathur (26, 41)
Charles Gaston (10, 33) Kevin Cash (20) Calsonic Kansei North America
The Pennsylvania State University Trox Tricia Bruenn (28)
Louis Starr (10) Jose Palma (20) Belimo Americas
Northwest Energy Efficiency Alliance Titus
Scott Fisher (28, 36, 48)
Ramez Afify (11) Curtis Peters (20) State Farm
E4P Consulting Engineering PLLC Nailor Industries
John McKernan (28)
Jason Atkisson (11, 32) David Pich (20) U.S. Environmental Protection Agency
Affiliated Engineers, Inc. Titus
Ken Mead (28)
Rex Scare (11) Jack Stegall (20) National Institute of Occupational Safety
Armstrong International, Inc. Energistics and Health
Steve Tredinnick (12, 13, 14) Michael Brendel (21) Eric Brodsky (29)
Burns & McDonnell, Inc. Lau Industries Research Products
Copyright © 2016, ASHRAE
This file is licensed to john Smith ([email protected]). Publication Date: 6/1/2016
Tom Justice (29) Ray Good (38) Greg Towsley (44)
ZENE, LLC Filtration Danfoss Turbocor Compressors, Inc.
Ken Fonstad (45)
Carolyn (Gemma) Kerr (29) Rick Heiden (38) ABB, Inc.
The Trane Company
Phil Maybee (29) Paul Lin (45)
The Filter Man Ltd. Justin Kauffman (38, 43) Regal Beloit
Johnson Controls
Larry Brand (31, 35) Tom Lowery (45)
Gas Technology Institute Alexander D. Leyderman (38, 43) Schneider Electric
Triumph Thermal Management Systems-
Mehdi M. Doura (31, 35) MD Marcelo Acosta (47)
Lochinvar LLC Armstrong Fluid Technology
Michael Perevozchikov (38)
Jennifer Guerrero-Ferreira (31, 35) Emerson Climate Technologies Eric Rosenberg (47)
Bekaert Corporation
Grumman/Butkus Associates
Lorenzo Cremaschi (39)
Tom Neill (31, 35) Oklahoma State University Steve Taylor (47)
Mestek Inc.
Satheesh Kulankara (39) Taylor Engineering, LLC
Bill Roy (31, 35) Johnson Controls, Inc.
Robert Walker (47)
Timco Rubber
Sankar Padhmanabhan (39) Belimo Aircontrols (USA), Inc.
Paul Sohler (31, 35) Danfoss LLC
c. Theodore E. Duffy (49, 50)
E, In Crown Boiler Co Mike Scofield (41) Johnson Supply
A Cory Weiss (31, 35) Conservation Mechanical Systems
R Kevin Mercer (49)
H Field Controls LLC
S Satyam Bendapudi (42) Carrier Corporation
A
6 Diane Jakobs (33) Carrier Corporation
1 Ray Rite (49, 50)
20 Rheem Manufacturing Company Laurant Abbas (43)
© Ingersoll Rand
er. George Yaeger (33) Arkema Don Schuster (49)
us Sears Holdings Corporation Fred Betz (38, 43)
gle Constantinos A. Balaras (37) PEDCO E & A Services, Inc. Ingersoll Rand
sin National Observatory of Athens Hermann Renz (38) Craig Messmer (50)
or Unico
d f Elena G. Dascalaki (37) Bitzer International
e Geoff Bares (51)
s National Observatory of Athens Niels Bidstrup (44)
n
e CB&I
c Grundfos Holding A/S
Li Svein Morner (37)
Sustainable Engineering Group LLC Larry Konopacz (44) Henry Becker (51)
Xylem - Applied Water Systems H-O-H Water Technology
Khalid Nagidi (37)
Energy Management Consulting Group, David Lee (44) Paul Steffes (51)
LLC Armstrong Fluid Technology Steffes Corporation
ASHRAE HANDBOOK COMMITTEE
Christopher J. Ahne, Chair
2016 HVAC Systems and Equipment Volume Subcommittee: Forrest S. Yount, Chair
Annette Dwyer Nicolas Lemire Paul A. Lindahl Patrick C. Marks Michael P. Patton
ASHRAE HANDBOOK STAFF
W. Stephen Comstock, Publisher
Director of Publications and Education
Mark S. Owen, Editor
Heather E. Kennedy, Managing Editor
Nancy F. Thysell, Typographer/Page Designer
David Soltis, Group Manager, and Jayne E. Jackson, Publication Traffic Administrator Publishing Services
This file is licensed to john Smith ([email protected]). Publication Date: 6/1/2016
ASHRAE Research: Improving the Quality of Life
ASHRAE is the world’s foremost technical society in the fields properties and building physics and to promote the application of
of heating, ventilation, air conditioning, and refrigeration. Its mem- innovative technologies.
bers worldwide are individuals who share ideas, identify needs, sup- Chapters in the ASHRAE Handbook are updated through the
port research, and write the industry’s standards for testing and experience of members of ASHRAE Technical Committees and
practice. The result is that engineers are better able to keep indoor through results of ASHRAE Research reported at ASHRAE confer-
environments safe and productive while protecting and preserving ences and published in ASHRAE special publications, ASHRAE
the outdoors for generations to come. Transactions, and ASHRAE’s journal of archival research, Science
One of the ways that ASHRAE supports its members’ and indus- and Technology for the Built Environment.
try’s need for information is through ASHRAE Research. Thou- For information about ASHRAE Research or to become a mem-
sands of individuals and companies support ASHRAE Research ber, contact ASHRAE, 1791 Tullie Circle N.E., Atlanta, GA 30329;
annually, enabling ASHRAE to report new data about material telephone: 404-636-8400; www.ashrae.org.
Preface
The 2016 ASHRAE Handbook—HVAC Systems and Equipment (cid:129) Chapter 33, Furnaces, has updates for current technology and effi-
discusses various systems and the equipment (components or ciency requirements.
assemblies) they comprise, and describes features and differences. (cid:129) Chapter 37, Solar Energy Equipment, has new data on worldwide
This information helps system designers and operators in selecting solar technology use, plus an expanded section on photovoltaic
and using equipment. ASHRAE Technical Committees in each sub- equipment.
ject area have reviewed all chapters and revised them as needed for (cid:129) Chapter 38, Compressors, has revisions on general theory; screw
current technology and practice. An accompanying CD-ROM con- and scroll compressors; and bearings, including oil-free technol-
c. tains all the volume’s chapters in both I-P and SI units. ogies.
n
E, I Some of the volume’s revisions and additions are as follows: (cid:129) Cinhlianpet,e srp 4li4t-,c oCuepnlterdif puugmal pPs;u hmypdsr,o nhiacs s ynsetwem c pounmtepn ts eolenc tvioenrt;i acnald,
A (cid:129) Chapter 7, Combined Heat and Power Systems, has a new section
R differential pressure control.
H on economic evaluation and includes an update on EU Directive
S 2004/8/EC. (cid:129) Chapter 45, Motors, Motor Controls, and Variable-Frequency
A Drives, has new content on standards, bearing currents, and
6 (cid:129) Chapter 9, Applied Heat Pump and Heat Recovery Systems, has
1 permanent-magnet motors.
0 new content on waste heat recovery, district applications, and in-
2 (cid:129) Chapter 47, Valves, has new content on control valve sizing; elec-
© dustrial process heat pumps. tronic actuators; and ball, butterfly, flow-limiting, and pressure-
er. (cid:129) CAhSaHpRteAr E12 r, eDseisatrrcicht pHreoajeticntg R aPn-d1 2C6o7o l(itnhge, hneaws n Dewis tcroicntt eHnet afrtionmg independent control valves.
s (cid:129) Chapter 49, Unitary Air Conditioners and Heat Pumps, has a new
u Guide and District Cooling Guide).
e map of U.S. regional appliance efficiency standards.
gl (cid:129) Chapter 18, Variable Refrigerant Flow, has new sections on mod- (cid:129) Chapter 50, Room Air Conditioners and Packaged Terminal Air
n eling and system commissioning, and an updated system design
si Conditioners, has updates for efficiency standards.
or example. (cid:129) Chapter 51, Thermal Storage, has new content on grid reliability,
d f (cid:129) Chapter 19, Duct Construction, has extensive revisions on system renewable power integration, heat storage, emergency cooling,
e leakage and air dispersion systems.
s water treatment, and commissioning.
n (cid:129) Chapter 20, Room Air Distribution Equipment, has updates for
e
c current technology, with new information on specialized compo- This volume is published, as a bound print volume and in elec-
Li
nents and air curtains. tronic format on CD-ROM and online, in two editions: one using
(cid:129) Chapter 21, Fans, has new sections on series fan operation and inch-pound (I-P) units of measurement, the other using the Interna-
field performance testing plus added content on fan and motor tional System of Units (SI).
efficiency grades and parallel multiple-fan operation. Corrections to the 2013, 2014, and 2015 Handbook volumes can
(cid:129) Chapter 24, Desiccant Dehumidification and Pressure-Drying be found on the ASHRAE website at www.ashrae.org and in the
Equipment, has expanded content on applications, air filters, and Additions and Corrections section of this volume. Corrections for
liquid strainers, plus recommendations from ASHRAE research this volume will be listed in subsequent volumes and on the
project RP-1339 on rating equipment at altitude. ASHRAE website.
(cid:129) Chapter 25, Mechanical Dehumidifiers and Related Components, Reader comments are enthusiastically invited. To suggest im-
has new content on psychrometrics, outdoor air, controls, and provements for a chapter, please comment using the form on the
industrial dehumidifiers. ASHRAE website or, using the cutout page(s) at the end of this
(cid:129) Chapter 26, Air-to-Air Energy Recovery Equipment, has new in- volume’s index, write to Handbook Editor, ASHRAE, 1791 Tullie
formation on heat pipes and desiccant and heat wheel systems. Circle N.E., Atlanta, GA 30329, or fax 678-539-2187, or e-mail
(cid:129) Chapter 28, Unit Ventilators, Unit Heaters, and Makeup Air [email protected].
Units, has revisions on standards, controls, and fan selection for
makeup air units.
(cid:129) Chapter 29, Air Cleaners for Particulate Contaminants, has up-
dates on standards and performance testing.
(cid:129) Chapter 31, Automatic Fuel-Burning Systems, has added content
on pneumatically and electronically linked gas/air ratio burner Mark S. Owen
systems. Editor
Copyright © 2016, ASHRAE
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Related Commercial Resources
CHAPTER 1
HVAC SYSTEM ANALYSIS AND SELECTION
Selecting a System...................................................................... 1.1 Security....................................................................................... 1.9
HVAC Systems and Equipment.................................................. 1.4 Automatic Controls and Building
Space Requirements................................................................... 1.6 Management Systems.............................................................. 1.9
Air Distribution.......................................................................... 1.8 Maintenance Management System............................................. 1.9
Pipe Distribution........................................................................ 1.8 Building System Commissioning.............................................. 1.10
A
N HVAC system maintains desired environmental conditions
in a space. In almost every application, many options are avail-
able to the design engineer to satisfy a client’s building program and
design intent. In the analysis, selection, and implementation of these
options, the design engineer should consider the criteria defined
here, as well as project-specific parameters to achieve the functional
requirements associated with the project design intent. In addition to
the design, equipment, and system aspects of the proposed design,
the design engineer should consider sustainability as it pertains to
c. responsible energy and environmental design, as well as constructa-
n
E, I bility of the design.
A HVAC systems are categorized by the method used to produce,
R deliver, and control heating, ventilating, and air conditioning in the
H
S conditioned area. This chapter addresses procedures for selecting an
A appropriate system for a given application while taking into account
6
1 pertinent issues associated with designing, building, commission-
0
2 ing, operating, and maintaining the system. It also addresses specific
© owner requirements and constraints associated with selecting the
er. optimum HVAC system for the application. Chapters 2 to 5 describe
us specific approaches and systems along with their attributes, based on
e their heating and cooling medium, the commonly used variations,
ngl constructability, commissioning, operation, and maintenance.
si This chapter is intended as a guide for the design engineer,
or builder, facility manager, and student needing to know or reference
d f the analysis and selection process that leads to recommending the
e
s optimum system for the job. The approach applies to HVAC conver-
n
e sion, building system upgrades, system retrofits, building renova-
c
Li tions and expansion, and new construction for any building: small,
medium, large, below grade, at grade, low-rise, and high-rise. This
system analysis and selection process (Figure 1) approach helps
determine the best system(s) for any building program, regardless
of facility type. This chapter’s analysis examines objective, subjec-
tive, short-term, and long-term goals. Figure 1 also highlights four
project delivery methods: performance contracting, design-bid-
build, design-build, and construction management. A fifth project
delivery method, integrated project delivery (IPD), can be consid-
ered an enhanced design-build approach in which the building
owner and the main subcontractors participate as active members of
the design-build team.
1. SELECTING A SYSTEM
The design engineer is responsible for considering various sys-
tems and equipment and recommending one or more system options
that will meet the project goals and perform as desired. It is impera-
tive that the design engineer and owner collaborate to identify and
prioritize criteria associated with the design goal. In addition, if the
project includes preconstruction services, the designer, owner, and
operator should consult with a construction manager to take advan-
tage of a constructability analysis as well as the consideration of
The preparation of this chapter is assigned to TC 9.1, Large Building Air- Fig. 1 Process Flow Diagram
Conditioning Systems. (Courtesy RDK Engineers)
1.1
Copyright © 2016, ASHRAE
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1.2 2016 ASHRAE Handbook—HVAC Systems and Equipment (SI)
value-engineered options. Occupant comfort (as defined by teria should address outside-the-building influences (e.g., smoke,
ASHRAE Standard 55), process heating, space heating, cooling, toxic fumes, flood, etc.) as well as influences inside the building.
and ventilation criteria should be considered and should include the System selection pertaining to HVAC security may require another
following: design team member, a security consultant, or the owner’s own
security group.
(cid:129) Temperature
(cid:129) Humidity System Constraints
(cid:129) Air motion
Once the goal criteria and additional goal options are listed,
(cid:129) Air purity or quality
many system constraints must be determined and documented.
(cid:129) Air changes per hour
These constraints may include the following:
(cid:129) Air and/or water velocity requirements
(cid:129) Local climate (cid:129) Performance limitations (e.g., temperature, humidity, space pres-
(cid:129) Space pressure requirements sure)
(cid:129) Capacity requirements, from a load calculation analysis (cid:129) Code requirements
(cid:129) Redundancy (cid:129) Available capacity
(cid:129) Spatial requirements (cid:129) Available space
(cid:129) Security concerns (cid:129) Available utility source
(cid:129) First cost (cid:129) Available infrastructure
(cid:129) Energy costs (cid:129) Building architecture
(cid:129) Operator labor costs (cid:129) System efficiency versus energy budget
(cid:129) Maintenance costs (cid:129) Operator knowledge and capabilities
(cid:129) Reliability (cid:129) Existing building occupants
(cid:129) Flexibility
The design engineer should closely coordinate the system con-
(cid:129) Controllability
straints with the rest of the design team, as well as the owner, to
nc. (cid:129) Life-cycle analysis overcome design obstacles associated with the HVAC systems
E, I (cid:129)(cid:129) SAucsotuaisntiacbsi laintyd ovfi bdreastiigonn under consideration for the project.
A
R (cid:129) Mold and mildew prevention Constructability Constraints
H
S Because these factors are interrelated, the owner, design engi- The design engineer must take into account HVAC system con-
A
6 neer, operator, and builder must consider how these criteria affect structability issues before the project reaches the construction
1 each other. The relative importance of factors such as these varies document phase. Some of these constraints may significantly
0
2 with different owners, and often changes from one project to affect the success of the design and cannot be overlooked in the
©
another for the same owner. For example, typical owner concerns design phase. Some issues and concerns associated with construc-
er. include first cost compared to operating cost, extent and frequency tability are
s
u of maintenance and whether that maintenance requires entering the
e occupied space, expected frequency of system failure, effect of fail- (cid:129) Existing conditions (e.g., floor load, access into and through a
gl building)
n ure, and time required to correct the failure. Each concern has a dif-
or si ferent priority, depending on the owner’s goals. (cid:129)(cid:129) RDiegmgionlgit iionnto and out of a building
d f Additional Goals (cid:129) Maintaining existing building occupancy and operation
e
ns In addition to the primary goal of providing the desired envi- (cid:129) Construction budget
e (cid:129) Construction schedule
c ronment, the design engineer should be aware of and account for
Li other goals the owner may require. These goals may include the (cid:129) Ability to phase HVAC system installation
(cid:129) Equipment availability (i.e., delivery lead times)
following:
(cid:129) Equipment ingress into designated space
(cid:129) Seasonal start-up date (cid:129) Equipment maintainability
(cid:129) Occupant move-in date
Few projects allow detailed quantitative evaluation of all alterna-
(cid:129) Operator training
tives. Common sense, historical data, and subjective experience can
(cid:129) Supporting a process, such as operation of computer equipment
be used to narrow choices to one or two potential systems.
(cid:129) Promoting a germ-free environment
Heating and air-conditioning loads often contribute to con-
(cid:129) Increasing marketability of rental spaces
straints, narrowing the choice to systems that fit in available space
(cid:129) Increasing net rental income
and are compatible with building architecture. Chapters 17 and 18
(cid:129) Increasing property salability
of the 2013 ASHRAE Handbook—Fundamentals describe meth-
(cid:129) Public image of the property
ods to determine the size and characteristics of heating and air-
The owner can only make appropriate value judgments if the conditioning loads. By establishing the capacity requirement,
design engineer provides complete information on the advantages equipment size can be determined, and the choice may be narrowed
and disadvantages of each option. Just as the owner does not usually to those systems that work well on projects within the required size
know the relative advantages and disadvantages of different HVAC range.
systems, the design engineer rarely knows all the owner’s financial Loads vary over time based on occupied and unoccupied periods,
and functional goals. Hence, the owner must be proactive and and changes in weather, type of occupancy, activities, internal loads,
involved in system selection in the conceptual phase of the job. The and solar exposure. Each space with a different use and/or exposure
same can be said for operator participation so that the final design may require its own control zone to maintain space comfort. Some
intent is sustainable. areas with special requirements (e.g., ventilation requirements) may
All owners should request and/or require the design team to pro- need individual systems. The extent of zoning, degree of control
vide building and HVAC security (as defined in Chapter 59 of the required in each zone, and space required for individual zones also
2015 ASHRAE Handbook—HVAC Applications). This security cri- narrow system choices.
This file is licensed to john Smith ([email protected]). Publication Date: 6/1/2016
HVAC System Analysis and Selection 1.3
No matter how efficiently a particular system operates or how Each chapter summarizes positive and negative features of vari-
economical it is to install, it can only be considered if it (1) main- ous systems. Comparing the criteria, other factors and constraints,
tains the desired building space environment within an acceptable and their relative importance usually identifies one or two systems
tolerance under expected conditions and occupant activities and (2) that best satisfy project goals. In making choices, notes should be
physically fits into, on, or adjacent to the building without causing kept on all systems considered and the reasons for eliminating those
objectionable occupancy conditions. that are unacceptable.
Cooling and humidity control are often the basis of sizing Each selection may require combining a primary system with a
HVAC components and subsystems, but ventilation requirements secondary (or distribution) system. The primary system converts
can also significantly impact system sizing. For example, if large energy derived from fuel or electricity to produce a heating and/or
quantities of outdoor air are required for ventilation or to replace air cooling medium. The secondary system delivers heating, ventila-
exhausted from the building, the design engineer may only need to tion, and/or cooling to the occupied space. The systems are indepen-
consider systems that transport and effectively condition those large dent to a great extent, so several secondary systems may work with
outdoor air volumes. a particular primary system. In some cases, however, only one sec-
Effective heat delivery to an area may be equally important in ondary system may be suitable for a particular primary system.
selection. A distribution system that offers high efficiency and com- Once subjective analysis has identified one or more HVAC sys-
fort for cooling may be a poor choice for heating. The cooling, tems (sometimes only one choice remains), detailed quantitative
humidity, and/or heat delivery performance compromises may be evaluations must be made. All systems considered should provide
small for one application in one climate, but may be unacceptable in satisfactory performance to meet the owner’s essential goals. The
another that has more stringent requirements. design engineer should provide the owner with specific data on each
HVAC systems and associated distribution systems often occupy system to make an informed choice. Consult the following chapters
a significant amount of space. Major components may also require to help narrow the choices:
special support from the structure. The size and appearance of ter-
(cid:129) Chapter 10 of the 2013 ASHRAE Handbook—Fundamentals cov-
minal devices (e.g., grilles, registers, diffusers, fan-coil units, radi-
ers physiological principles, comfort, and health.
ant panels, chilled beams) affect architectural design because they
c. (cid:129) Chapter 19 of the 2013 ASHRAE Handbook—Fundamentals cov-
E, In areC voisnibstler uinc ttihoen obcucdugpeietd c ospnasctrea.ints can also influence the choice (cid:129) Cerhsa mpteetrh 3o6d so ff othr ee 2st0im15a AtinSgH aRnAnEu aHl aenndebrgoyo kc—osHtsV.AC Applications
A of HVAC systems. Based on historical data, some systems may not
R covers methods for energy management.
H be economically viable within the budget limitations of an owner’s (cid:129) Chapter 37 of the 2015 ASHRAE Handbook—HVAC Applications
S building program. In addition, annual maintenance and operating
A covers owning and operating costs.
6 budget (utilities, labor, and materials) should be an integral part of (cid:129) Chapter 39 of the 2015 ASHRAE Handbook—HVAC Applications
01 any system analysis and selection process. This is particularly covers operation and maintenance management.
© 2 important for building owners who will retain the building for a (cid:129) Chapter 48 of the 2015 ASHRAE Handbook—HVAC Applications
er. s(1u)b sctoasntt-idarli vneunm pbeerrf oofrm yeaanrcse., Vwahluiceh- emngaiyn eperorevdid seo lau tbieotntes rc saonl uotfifoenr covers noise and vibration control.
s
u for lower first cost; (2) a more sustainable solution over the life of Other documents and guidelines that should be consulted are
gle the equipment; or (3) best value based on a reasonable return on ASHRAE standards; local, state, and federal guidelines; and special
n investment. agency requirements [e.g., U.S. General Services Administration
ed for si ltoraniSgnu-etdset rtamoi n epaffrbiocljeiee cnett nlsyeu rcagcnyed s esc focfneacsnut ibmvee pllytoi sootpn ie fr cabatunei ladbniedn gmc ooampineptraraoitnmo rtihss eea dbre u ainlndod-t (oGGnu SiAdAec)lc,i rnFeedosio tIdant siatonintdu toDef r(HuFgGe aIAl)t,dh Lmceaiarnedi seOtrrsarhgtiiaopnn ii nz(a FEtDinoeAnrs)g ,y (JJ aoCniAndt H ECOnov)m,i rmFonaiscmsilieiontyn-
ns ing systems. For projects in which the design engineer used some tal Design (LEED®)]. Additional sources of detailed information
e
c form of energy software simulation, the resultant data should be are listed in the Bibliography and/or available in the ASHRAE
Li passed on to the building owner so that goals and expectations can Bookstore (www.ashrae.org/bookstore).
be measured and benchmarked against actual system performance.
Selection Report
Even though the HVAC designer’s work may be complete after
system commissioning and turnover to the owner, continuous As the last step, the design engineer should prepare a summary
acceptable performance is expected. Refer to ASHRAE Guideline 0 report that addresses the following:
and to ASHRAE’s Building Energy Quotient (bEQ) program (www
(cid:129) The originally established goals
.buildingeq.com/).
(cid:129) Criteria for selection
System operability should be a consideration in the system (cid:129) Important factors, including advantages and disadvantages
selection. Constructing a highly sophisticated, complex HVAC sys- (cid:129) System integration with other building systems
tem in a building where maintenance personnel lack the required (cid:129) Other goals
skills can be a recipe for disaster at worst, and at best requires the (cid:129) Security criteria
use of costly outside maintenance contractors to achieve successful (cid:129) Building envelope
system operation. (cid:129) Project timeline (design, equipment delivery, commissioning,
training, and construction)
Narrowing the Choices
(cid:129) Basis of design
The following chapters in this volume present information to (cid:129) HVAC system analysis and selection matrix
help the design engineer narrow the choices of HVAC systems: (cid:129) System narratives
(cid:129) Budget costs (first cost, operating cost, and energy cost)
(cid:129) Chapter 2 focuses on a distributed approach to HVAC.
(cid:129) Final recommendation(s)
(cid:129) Chapter 3 provides guidance for large equipment centrally
located in or adjacent to a building. A brief outline of each of the final selections should be provided.
(cid:129) Chapter 4 addresses all-air systems. In addition, HVAC systems deemed inappropriate should be noted
(cid:129) Chapter 5 covers building piping distribution, including in-room as having been considered but not found applicable to meet the
terminal systems. owner’s primary HVAC goal.
This file is licensed to john Smith ([email protected]). Publication Date: 6/1/2016
1.4 2016 ASHRAE Handbook—HVAC Systems and Equipment (SI)
Table 1 Sample HVAC System Analysis and Selection Matrix (0 to 10 Score)
Goal: Furnish and install an HVAC system that provides moderate space temperature
control with minimum humidity control at an operating budget of 220 kW/m2 per year
Categories System #1 System #2 System #3 Remarks
1. Criteria for Selection:
(cid:129) 25.6°C space temperature with 1.7 K control during occupied cycle, with
40%rh and rh control during cooling.
(cid:129) 20°C space temperature with , with 20% rh and 5% rh control during
heating season.
(cid:129) First cost
(cid:129) Equipment life cycle
2. Important Factors:
(cid:129) First-class office space stature
(cid:129) Individual tenant utility metering
3. Other Goals:
(cid:129) Engineered smoke control system
(cid:129) ASHRAE Standard 62.1 ventilation rates
(cid:129) Direct digital control building automation
4. System Constraints:
(cid:129) No equipment on first floor
(cid:129) No equipment on ground adjacent to building
5. Energy use as predicted by use of an industry-acceptable computerized energy
c. model
n
E, I 6. Other Constraints:
A (cid:129) No perimeter finned-tube radiation or other type of in-room equipment
R
H TOTAL SCORE
S
A
6
01 The report should include an HVAC system selection matrix that 2. HVAC SYSTEMS AND EQUIPMENT
© 2 identifies the one or two suggested HVAC system selections (pri- Many built, expanded, and/or renovated buildings may be ideally
er. omthareyr acnodn stsreacionntsd aarnyd, wcohnesni daepraptliiocnasb.l eI)n, scyosmtepmle tcinogn sttrhaiisn tms, aatrnixd suited for decentralized HVAC systems, with equipment located in,
s throughout, adjacent to, or on top of the building. The alternative to
e u assessment, the design engineer should have, and identify in the this decentralized approach is to use primary equipment located in
gl report, the owner’s input to the analysis. This input can also be a central plant (either inside or outside the building) with water and/
n
si applied as weighted multipliers, because not all criteria carry the or air required for HVAC needs distributed from this plant.
or same weighted value.
d f Many grading methods are available to complete an analytical Decentralized System Characteristics
e
s matrix analysis. Probably the simplest is to rate each item excellent, The various types of decentralized systems are described in
n
e very good, good, fair, or poor. A numerical rating system such as 0 Chapter 2. The common element is that the required cooling is dis-
c
Li to 10, with 10 equal to excellent and 0 equal to poor or not applica- tributed throughout the building, with direct-expansion cooling of
ble, can provide a quantitative result. The HVAC system with the air systems.
highest numerical value then becomes the recommended HVAC Temperature, Humidity, and Space Pressure Requirements.
system to accomplish the goal. A decentralized system may be able to fulfill any or all of these
design parameters, but typically not as efficiently or as accurately as
The system selection report should include a summary followed
a central system.
by a more detailed account of the HVAC system analysis and sys-
Capacity Requirements. A decentralized system usually re-
tem selection. This summary should highlight key points and find-
quires each piece of equipment to be sized for zone peak capacity,
ings that led to the recommendation(s). The analysis should refer to
unless the systems are variable-volume. Depending on equipment
the system selection matrix (such as in Table 1) and the reasons for
type and location, decentralized systems do not benefit as much
scoring.
from equipment sizing diversity as centralized systems do.
With each HVAC system considered, the design engineer should Redundancy. A decentralized system may not have the benefit
note the criteria associated with each selection. Issues such as of back-up or standby equipment. This limitation may need review.
close-tolerance temperature and humidity control may eliminate Facility Management. A decentralized system can allow the
some HVAC systems from consideration. System constraints, building manager to maximize performance using good business/
noted with each analysis, should continue to eliminate potential facility management techniques in operating and maintaining the
HVAC systems. Advantages and disadvantages of each system HVAC equipment and systems.
should be noted with the scoring from the HVAC system selection Spatial Requirements. A decentralized system may or may not
matrix. This process should reduce HVAC selection to one or require equipment rooms. Because of space restrictions imposed on
two optimum choices for presentation to the owner. Examples of the design engineer or architect, equipment may be located on the
similar installations for other owners should be included with this roof and/or the ground adjacent to the building. Depending on sys-
report to support the final recommendation. Identifying a third tem components, additional space may be required in the building
party for an endorsement allows the owner to inquire about the suc- for chillers and boilers. Likewise, a decentralized system may or
cess of other HVAC installations. may not require duct and pipe shafts throughout the building.
This file is licensed to john Smith ([email protected]). Publication Date: 6/1/2016
HVAC System Analysis and Selection 1.5
First Cost. A decentralized system probably has the best first- tral system equipment has a longer equipment service life to com-
cost benefit. This feature can be enhanced by phasing in the pur- pensate for this shortcoming. Thus, a life-cycle cost analysis is very
chase of decentralized equipment as needed (i.e., buying equipment important when evaluating central versus decentralized systems.
as the building is being leased/occupied). Operating Cost. A central system usually has the advantage of
Operating Cost. A decentralized system can save operating cost larger, more energy-efficient primary equipment compared to
by strategically starting and stopping multiple pieces of equipment. decentralized system equipment. In addition, the availability of
When comparing energy consumption based on peak energy draw, multiple pieces of HVAC equipment allows staging of this equip-
decentralized equipment may not be as attractive as larger, more ment operation to match building loads while maximizing opera-
energy-efficient centralized equipment. tional efficiency.
Maintenance Cost. A decentralized system can save mainte- Maintenance Cost. The equipment room for a central system
nance cost when equipment is conveniently located and equipment provides the benefit of being able to maintain HVAC equipment
size and associated components (e.g., filters) are standardized. away from occupants in an appropriate service work environment.
When equipment is located outdoors, maintenance may be difficult Access to occupant workspace is not required, thus eliminating dis-
during bad weather. ruption to the space environment, product, or process. Because of
Reliability. A decentralized system usually has reliable equip- the typically larger capacity of central equipment, there are usually
ment, although the estimated equipment service life may be less fewer pieces of HVAC equipment to service.
than that of centralized equipment. Decentralized system equipment Reliability. Centralized system equipment generally has a lon-
may, however, require maintenance in the occupied space. ger service life.
Flexibility. A decentralized system may be very flexible because Flexibility. Flexibility can be a benefit when selecting equip-
it may be placed in numerous locations.
ment that provides an alternative or back-up source of HVAC.
Level of Control. Decentralized systems often use direct
refrigerant expansion (DX) for cooling, and on/off or staged heat. Air Distribution Systems
This step control results in greater variation in space temperature
The various air distribution systems, including dedicated outdoor
and humidity, where close control is not desired or necessary. As
E, Inc. ah ucmauitdiiotny, loevveerlssi aznindg m DoXld o or rs tmepilpdeedw c oporolibnlge mcasn. allow high indoor asyirs Lsteyemsvt eetmly pose f(s D CdOiosAncutSrs)os, ela.d re Cc daeennt tabriaell eiudzse iednd Cisnyh sactpoetnmejrus 4 n.gc Aetinonenyr aowlfli ytthh e uD speOr eAccheSdi.lilnegd
A Noise and Vibration. Decentralized systems often locate noisy
R water for cooling, and steam or hydronic heat. This usually allows
machinery close to building occupants, although equipment noise
H for close control of space temperature and humidity where desired
S may be less than that produced by large central systems.
A or necessary.
16 muCltiopnlest raundct asibmiliiltayr.- iDne-scieznet reaqliuziepdm seynstt etmhast f rmeaqkueesn tslyta cnodnasrdisitz oaf- Sound and Vibration. Centralized systems often locate noisy
20 tion a construction feature, as well as purchasing units in large machinery sufficiently remote from building occupants or noise-
© sensitive processes.
quantities.
er. Constructability. Centralized systems usually require more coor-
s Centralized System Characteristics dinated installation than decentralized systems. However, consolida-
u
e These systems are characterized by central refrigeration systems tion of the primary equipment in a central location also has benefits.
ngl and chilled-water distribution. This distribution can be to one or Among the largest centralized systems are HVAC plants serving
ed for si Dfmloeootrarei lmsc hoaijflo lterh dfe-aswne asrtoyeosrt meamsi,r s-d haearpene dcnlodinvingegr e uodnn ii ntbs u Cithlhdaripontugeg rsh 3ioz.eu,t otrh teo fbluoioldr-ibnyg-. geinrrdaoliulvypi sdo uopafel rl aactreegn emt rbaoulr iepl delaifnnfigtcssi..e ETntchloyens, eow mpitlihac n loctsow inmesrip dmreoarvainetit oednnivsae norcsfei t lcyao ragsntesdr, gtcheeannn--
ns Temperature, Humidity, and Space Pressure Requirements. tralized systems require extensive analysis. The utility analysis
ce A central system may be able to fulfill any or all of these design may consider multiple fuels and may also include gas and steam
Li parameters, and typically with greater precision and efficiency than turbine-driven equipment. Multiple types of primary equipment
a decentralized system. using multiple fuels and types of HVAC-generating equipment
Capacity Requirements. A central system usually allows the (e.g., centrifugal and absorption chillers) may be combined in one
design engineer to consider HVAC diversity factors that reduce plant. Chapters 13 to 15 provide design details for central plants.
installed equipment capacity. As a result, this offers some attractive
Primary Equipment
first-cost and operating-cost benefits.
Redundancy. A central system can accommodate standby The type of decentralized and centralized equipment selected for
equipment that decentralized configurations may have trouble buildings depends on a well-organized HVAC analysis and selection
accommodating. report. The choice of primary equipment and components depends
Facility Management. A central system usually allows the on factors presented in the selection report (see the section on
building manager to maximize performance using good business/ Selecting a System). Primary HVAC equipment includes refrigera-
facility management techniques in operating and maintaining the tion equipment; heating equipment; and air, water, and steam deliv-
HVAC equipment and systems. ery equipment.
Spatial Requirements. The equipment room for a central sys- Many HVAC designs recover internal heat from lights, people,
tem is normally located outside the conditioned area: in a basement, and equipment to reduce the size of the heating plant. In buildings
penthouse, service area, or adjacent to or remote from the building. with core areas that require cooling while perimeter areas require
A disadvantage of this approach may be the additional cost to fur- heating, one of several heat reclaim systems can heat the perimeter
nish and install secondary equipment for the air and/or water dis- to save energy. Sustainable design is also important when consider-
tribution. Other considerations are the access requirements and ing recovery and reuse of materials and energy. Chapter 9 describes
physical constraints that exist throughout the building to the instal- heat pumps and some heat recovery arrangements, Chapter 37
lation of the secondary distribution network of ducts and/or pipes describes solar energy equipment, and Chapter 26 introduces air-
and for equipment replacement. to-air energy recovery. In the 2015 ASHRAE Handbook—HVAC
First Cost. Even with HVAC diversity, a central system may not Applications, Chapter 36 covers energy management and Chapter
be less costly than decentralized HVAC systems. Historically, cen- 41 covers building energy monitoring. Chapter 35 of the 2013
This file is licensed to john Smith ([email protected]). Publication Date: 6/1/2016
1.6 2016 ASHRAE Handbook—HVAC Systems and Equipment (SI)
ASHRAE Handbook—Fundamentals provides information on sus- Air Delivery Equipment
tainable design.
Primary air delivery equipment for HVAC systems is classified
The search for energy savings has extended to cogeneration or as packaged, manufactured and custom-manufactured, or field-
total energy [combined heat and power (CHP)] systems, in fabricated (built-up). Most air delivery equipment for large systems
which on-site power generation is added to the HVAC project. The uses centrifugal or axial fans; however, plug or plenum fans are
economic viability of this function is determined by the difference often used. Centrifugal fans are frequently used in packaged and
between gas and electric rates and by the ratio of electricity to heat- manufactured HVAC equipment. One system rising in popularity is
ing demands for the project. In these systems, waste heat from gen- a fan array, which uses multiple plug fans on a common plenum
erators can be transferred to the HVAC systems (e.g., to drive wall, thus reducing unit size. Axial fans are more often part of a cus-
turbines of centrifugal compressors, serve an absorption chiller, tom unit or a field-fabricated unit. Both types of fans can be used as
provide heating or process steam). Chapter 7 covers cogeneration or industrial process and high-pressure blowers. Chapter 21 describes
total energy systems. Alternative fuel sources, such as waste heat fans, and Chapters 19 and 20 provide information about air delivery
boilers, are now being included in fuel evaluation and selection for components.
HVAC applications.
Thermal storage is another cost-saving concept, which provides 3. SPACE REQUIREMENTS
the possibility of off-peak generation of chilled water or ice. Ther-
In the initial phase of building design, the design engineer sel-
mal storage can also be used for storing hot water for heating. Many
dom has sufficient information to render the optimum HVAC design
electric utilities impose severe charges for peak summer power use
for the project, and its space requirements are often based on per-
or offer incentives for off-peak use. Storage capacity installed to
centage of total area or other experiential rules of thumb. The final
level the summer load may also be available for use in winter, thus
design is usually a compromise between the engineer’s recommen-
making heat reclaim a viable option. Chapter 51 has more informa-
dations and the architectural considerations that can be accommo-
tion on thermal storage.
dated in the building. An integrated project design (IPD) approach,
With ice storage, colder supply air can be provided than that as recommended by the American Institute of Architects (AIA), can
c. available from a conventional chilled-water system. This colder air address these problems early in the design process; see Chapter 58
n
AE, I asollmowe sl oucsaet ioofn ssm) aolpleerr aftainnsg acnods td. uAcdtsd, iwtiohnicahl rpeidpue caensd f idrustc ct oinsts uanladt i(oinn toifm tehse, t2h0e1 b5u iAldSiHngR AoEw nHera,n wdbhooo mk—ayH pVrAefCe r Aepitphleicr aat icoennst. raAlitz eodth oerr
R is often required, however, contributing to a higher first cost. These decentralized system, may dictate final design and space require-
SH life-cycle savings can offset the first cost for storage provisions and ments. This section discusses some of these requirements.
A the energy cost required to make ice. Similarly, thermal storage of
6 hot water can be used for heating. Equipment Rooms
1
0
2 Total mechanical and electrical space requirements range
© Refrigeration Equipment between 4 and 9% of gross building area, with most buildings in the
er. Chapters 2 and 3 summarize the primary types of refrigeration 6 to 9% range. These ranges include space for HVAC, electrical,
s
u equipment for HVAC systems. plumbing, and fire protection equipment and may also include ver-
gle When chilled water is supplied from a central plant, as on uni- tical shaft space for mechanical and electrical distribution through
n versity campuses and in downtown areas of large cities, the utility the building.
ed for si smseeerlevncitctsie oo nfp rtthooev disdeeetrerv rismcheio.nuel da vbaei lcaobniltiatyc,t ecdo sdtu, rainngd tshyes tespme cainfiacl yrseiqsu airned- lmayizMoeu oltoss;nt agen qdduu i(cp3tm), cpeeinpnte trr,o aalonimzde s cm oshanoidnuutleidtn rabunenc sce e aannntdrd a solilzpyee lsro;a ct(ia2ot)ne sd. iW mtopi t(lhi1f )sy h msohirnatefir-t
ns duct and pipe runs, a central location could also reduce pump and
ce Heating Equipment fan motor power requirements, which reduces building operating
Li costs. But, for many reasons, not all mechanical and electrical
Steam boilers and heating-water boilers are the primary means of
equipment rooms can be centrally located in the building. In any
heating a space using a centralized system, as well as some decen-
case, equipment should be kept together whenever possible to min-
tralized systems. These boilers may be (1) used both for comfort and
imize space requirements, centralize maintenance and operation,
process heating; (2) manufactured to produce high or low pressure;
and simplify the electrical system.
and (3) fired with coal, oil, electricity, gas, and even some waste
Equipment rooms generally require clear ceiling height ranging
materials. Low-pressure boilers are rated for a working pressure of
from 3 to 5 m, depending on equipment sizes and the complexity of
either 100 or 200 kPa for steam, and 1100kPa for water, with a tem-
air and/or water distribution.
perature limit of 120°C. Packaged boilers, with all components and
The main electrical transformer and switchgear rooms should be
controls assembled at the factory as a unit, are available. Electrode
located as close to the incoming electrical service as practical. If
or resistance electric boilers that generate either steam or hot water
there is an emergency generator, it should be located considering (1)
are also available. Chapter 32 has further information on boilers,
proximity to emergency electrical loads and sources of combustion
and Chapter 27 details air-heating coils.
and cooling air and fuel, (2) ease of properly venting exhaust gases
Where steam or hot water is supplied from a central plant, as on to the outdoors, and (3) provisions for noise control.
university campuses and in downtown areas of large cities, the util- Primary Equipment Rooms. The heating equipment room
ity provider should be contacted during project system analysis and houses the boiler(s) and possibly a boiler feed unit (for steam boil-
selection to determine availability, cost, and specific requirements ers), chemical treatment equipment, pumps, heat exchangers, pres-
of the service. sure-reducing equipment, air compressors, and miscellaneous
When primary heating equipment is selected, the fuels consid- ancillary equipment. The refrigeration equipment room houses the
ered must ensure maximum efficiency. Chapter 31 discusses design, chiller(s) and possibly chilled-water and condenser water pumps,
selection, and operation of the burners for different types of primary heat exchangers, air-conditioning equipment, air compressors,
heating equipment. Chapter 28 of the 2013 ASHRAE Handbook— and miscellaneous ancillary equipment. Design of these rooms
Fundamentals describes types of fuel, fuel properties, and proper needs to consider (1) equipment size and weight, (2) installation,
combustion factors. maintenance, and replacement, (3) applicable regulations relative to
This file is licensed to john Smith ([email protected]). Publication Date: 6/1/2016
HVAC System Analysis and Selection 1.7
combustion air and ventilation air, and (4) noise and vibration trans- floors. High-rise buildings may opt for decentralized fan rooms for
mission to adjacent spaces. Consult ASHRAE Standard 15 for each floor, or for more centralized service with one fan room serv-
refrigeration equipment room safety requirements. ing the lower 10 to 20 floors, one serving the middle floors of the
Most air-conditioned buildings require a cooling tower or other building, and one at the roof serving the top floors.
type of heat rejection equipment. If the cooling tower or water- Life safety is a very important factor in HVAC fan room location.
cooled condenser is located at ground level, it should be at least Chapter 53 of the 2015 ASHRAE Handbook—HVAC Applications
30m away from the building to (1) reduce tower noise in the build- discusses fire and smoke control. State and local codes have addi-
ing, (2) keep discharge air and moisture carryover from fogging the tional fire and smoke detection and damper criteria.
building’s windows and discoloring the building facade, and (3)
Horizontal Distribution
keep discharge air and moisture carryover from contaminating out-
door air being introduced into the building. Cooling towers should Most decentralized and central systems rely on horizontal dis-
be kept a similar distance from parking lots to avoid staining car fin- tribution. To accommodate this need, the design engineer needs to
ishes with atomized water treatment chemicals. Chapters 39 and 40 take into account the duct and/or pipe distribution criteria for instal-
have further information on this equipment. lation in a ceiling space or below a raised floor space. Systems using
It is often economical to locate the heating and/or refrigeration water distribution usually require the least amount of ceiling or
plant in the building, on an intermediate floor, in a roof penthouse, raised floor depth, whereas air distribution systems have the largest
or on the roof. Electrical service and structural costs are higher, but demand for horizontal distribution height. Steam systems need to
these may be offset by reduced costs for piping, pumps and pumping accommodate pitch of steam pipe, end of main drip, and condensate
energy, and chimney requirements for fuel-fired boilers. Also, ini- return pipe pitch. Another consideration in the horizontal space cav-
tial cost of equipment in a tall building may be less for equipment ity is accommodating the structural members, light fixtures, rain
located on a higher floor because some operating pressures may be leaders, cable trays, etc., that can fill up this space.
lower with boilers located in a roof penthouse.
Vertical Shafts
Regulations applicable to both gas and fuel oil systems must be
followed. Gas fuel may be more desirable than fuel oil because of Buildings over three stories high usually require vertical shafts to
nc. the physical constraints on the required fuel oil storage tank, as well consolidate mechanical, electrical, and telecommunication distribu-
E, I as specific environmental and safety concerns related to oil leaks. In tion through the facility.
A addition, the cost of an oil leak detection and prevention system may Vertical shafts in the building provide space for air distribution
R
H be substantial. Oil pumping presents added design and operating ducts and for pipes. Air distribution includes HVAC supply air,
S problems, depending on location of the oil tank relative to the oil return air, and exhaust air ductwork. If a shaft is used as a return air
A
6 burner. plenum, close coordination with the architect is necessary to ensure
1 Energy recovery systems can reduce the size of the heating and/ that the shaft is airtight. If the shaft is used to convey outdoor air to
0
2 or refrigeration plant. The possibility of failure or the need to take decentralized systems, close coordination with the architect is also
©
heat recovery equipment out of operation for service should be necessary to ensure that the shaft is constructed to meet mechanical
er. considered in the heating plant design, to ensure the ability to heat code requirements and to accommodate the anticipated internal
s
u the building with the heating plant without heat recovery. Well- pressure. The temperature of air in the shaft must be considered
e insulated buildings and electric and gas utility rate structures may when using the shaft enclosure to convey outdoor air. Pipe distribu-
gl
n encourage the design engineer to consider energy conservation tion includes heating water, chilled water, condenser water, and
ed for si cstoonrcaegpet.s such as limiting demand, ambient cooling, and thermal sfeotleeuacnmtdri cisn uc vopenprdltyiuc iaatsln /dsch loacsfoetnst sdo,e rtn elsolaectpaeht eorden tevu ercnrat.bi clOainltlghy/e cirln o dtsihesettsr b,i buuuinltdiinointneg r sriuynspcttleiubmdlees
ns Fan Rooms power supply (UPS), plumbing, fire protection piping, pneumatic
e
c Fan rooms house HVAC air delivery equipment and may include tubes, and conveyers.
Li other miscellaneous equipment. The room must have space for Vertical shafts should not be adjacent to stairs, electrical closets,
removing the fan(s), shaft(s), coils, and filters. Installation, replace- and elevators unless at least two sides are available to allow access
ment, and maintenance of this equipment should be considered to ducts, pipes, and conduits that enter and exit the shaft while
when locating and arranging the room. allowing maximum headroom at the ceiling. In general, duct shafts
Fan rooms in a basement that has an airway for intake of outdoor with an aspect ratio of 2:1 to 4:1 are easier to develop than large
air present a potential problem. Low air intakes are a security con- square shafts. The rectangular shape also facilitates transition from
cern, because harmful substances could easily be introduced (see the equipment in the fan rooms to the shafts.
the section on Security). Placement of the air intake louver(s) is also In multistory buildings, a central vertical distribution system
a concern because debris and snow may fill the area, resulting in with minimal horizontal branch ducts is desirable. This arrangement
safety, health, and fan performance concerns. Parking areas close to (1) is usually less costly; (2) is easier to balance; (3) creates less con-
the building’s outdoor air intake may compromise ventilation air flict with pipes, beams, and lights; and (4) enables the architect to
quality. design lower floor-to-floor heights. These advantages also apply to
Fan rooms located at the perimeter wall can have intake and vertical water and steam pipe distribution systems.
exhaust louvers at the location of the fan room, subject to coordina- The number of shafts is a function of building size and shape. In
tion with architectural considerations. Interior fan rooms often larger buildings, it is usually more economical in cost and space to
require intake and exhaust shafts from the roof because of the diffi- have several small shafts rather than one large shaft. Separate HVAC
culty (typically caused by limited ceiling space) in ducting intake supply, return, and exhaust air duct shafts may be desirable to
and exhaust to the perimeter wall. reduce the number of duct crossovers. The same applies for steam
Fan rooms on the second floor and above have easier access for supply and condensate return pipe shafts because the pipe must be
outdoor and exhaust air. Depending on the fan room location, equip- pitched in the direction of flow.
ment replacement may be easier. The number of fan rooms required When future expansion is a consideration, a pre-agreed percent-
depends largely on the total floor area and whether the HVAC sys- age of additional shaft space should be considered for inclusion.
tem is centralized or decentralized. Buildings with large floor areas This, however, affects the building’s first cost because of the addi-
may have multiple decentralized fan rooms on each or alternate tional floor space that must be constructed. The need for access
