Large Building Air-Conditioning Systems
ASHRAE Technical Committee 9.1

Scope of TC 9.1

TC 9.1 is concerned with the general design concepts of the HVAC systems that are utilized for the conditioning of large buildings, including the integration of components into centralized and decentralized systems.


The ASHRAE Handbook is published in a series of four volumes, one of which is revised each year, ensuring that no volume is older than four years.

TC 9.1 is responsible for the following chapters in the ASHRAE HVAC SYSTEMS AND EQUIPMENT Handbook:

HVAC Analysis & Selection

This chapter is intended as a guide for the design engineer, builder, facility manager, and student needing to know or reference the analysis and selection process that leads to recommending the optimum system for the job. The approach applies to HVAC con-version, building system upgrades, system retrofits, building renovations 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 helps determine the optimum system(s) for any building, regardless of facility type. Analysis examines objective, subjective, short-term, and long-term goals.

Decentralized Heating & Cooling

For most small to mid-size installations, decentralized cooling and heating is usually preferable to a centralized system (see Chapter 3). Frequently classified as packaged unit systems (al-though many are far from being a single packaged unit), decentralized systems can be found in almost all classes of buildings. They are especially suitable for smaller projects with no central plant, where low initial cost and simplified installation are important. These systems are installed in office buildings, shopping centers, manufacturing plants, schools, health care facilities, hotels, motels, apartments, nursing homes, and other multiple-occupancy dwellings. They are also suited to air conditioning existing buildings with limited life or income potential. Applications also include facilities requiring specialized high performance levels, such as computer rooms and research laboratories.

Although some of the equipment addressed here can be applied as a single unit, this chapter covers applying multiple units to form a complete heating and air-conditioning system for a building and the distribution associated with some of these systems. For guidance on HVAC system selection, see "HVAC Analysis and Selection".

Central Heating & Cooling Plants

Central cooling and/or heating plants generate cooling and/or heating in one location for distribution to multiple locations in one building or an entire campus or neighborhood, and represent approximately 25% of HVAC system applications. Central cooling and heating systems are used in almost all classes of buildings, but particularly in very large buildings and complexes or where there is a high density of energy use. They are especially suited to applications where maximizing equipment service life and using energy and operational workforce efficiently are important.

The following facility types are good candidates for central cooling and/or heating systems: (1) Campus environments with distribution to several buildings; (2) High-rise facilities; (3) Large office buildings; (4) Large public assembly facilities, entertainment complexes, stadiums, arenas, and convention and exhibition centers; (5) Urban centers (e.g., city centers/districts); (6) Shopping malls; (7) Large condominiums, hotels, and apartment complexes; (8) Educational facilities; (9) Hospitals and other health care facilities; (10) Industrial facilities (e.g., pharmaceutical, manufacturing); (11) Large museums and similar institutions; (12) Locations where waste heat is readily available (result of power generation or industrial processes)

This chapter addresses design alternatives that should be considered when centralizing a facility’s cooling and heating sources. Distribution system options and equipment are discussed when they relate to the central equipment, but more information on distribution systems can be found in later chapters.

Air Handling & Distribution

Very early in the design of a new or retrofit building project, the HVAC design engineer must analyze and ultimately select the basic systems, and whether production of primary heating and cooling should be decentralized or central. This chapter covers the options, processes, available equipment, and challenges of all-air systems; for all-water, air-and-water, and local terminal systems. For additional system selection tools, refer to the HVAC System Analysis and Selection Matrix in ASHRAE Handbook Online+ (

In-Room Terminals

Very early in the design process, the HVAC design engineer must analyze and ultimately select appropriate systems, as discussed in "HVAC Analysis and Selection". Next, production of heating and cooling is selected as decentralized or centralized. Finally, distribution of heating and cooling to the end-use space can be done by an all-air system, or a variety of all-water or air-water systems and local terminals, as discussed in this chapter.

The ASHRAE HVAC SYTEMS & EQUIPMENT HANDBOOK may be purchased from the on-line bookstore by clicking on the highlighted text.

Comment on the Handbook: ASHRAE welcomes your comments on the Handbook or a specific Handbook chapter.  To submit a comment about any aspect or part of the Handbook series, you can use the Handbook Comment Form.

Review a Handbook Chapter: To provide your feedback about a specific Handbook chapter, you can answer the brief survey questions on the Handbook Chapter Review Form.


Technical committees develop and sponsor technical sessions at the winter and annual conferences. Information about their future technical program is discussed at each TC meeting and at the TC’s Program Subcommittee meeting.

ASHRAE publishes papers and transactions from presentations at its conference events. In addition, ASHRAE records most of the seminar sessions from its conferences on DVD. These DVDs are ideal for use at chapter meetings, in university courses, or company lunch and learns. Products available from the most recent conference may be found here.

TC 9.1 sponsored these technical sessions at past conferences.

Winter 2020 Orlando

Seminar 9 - Cutting Edge Approaches to a 21st Century Learning Environment
Chair: Bill Artis, BCXP, BEAP, BEMP, Member, Energy Project Consulting LLC, NEW HYDE PARK, NY
1. The Transformation of Marston Hall: Creating a 21st Century Learning Environment within a 19th Century Structure, Lincoln Pearce, P.E., BEAP, Member, IMEG Corp, Des Moines, IA
2. You Can Teach a Historic School of Architecture New Tricks, Kelley Cramm, P.E., Member, Henderson Engineers, Lenexa, KS

Winter 2019 Atlanta

Seminar 16 - The Best of Engineer’s Notebook 3rd Edition Track: Common System Issues and Misapplications
•Chair: Kelley Cramm, P.E., Member, Henderson Engineers, Lenexa, KS
•Data Centers, Cooling Towers and Thermal Storage Daniel H Nall, WSP Flack + Kurtz, New York, NY •Designing Pipe Insulation Systems Kent W. Peterson, P.E., BEAP, Presidential Fellow ASHRAE, P2S Engineering, Inc., Long Beach, CA 
•Making VAV Great Again Steve Taylor, P.E., Fellow ASHRAE, Taylor Engineering, Alameda, CA
•N+1 HVAC for IT Closets and Server Rooms Stephen W. Duda, P.E., BEAP, HBDP and HFDP, Fellow ASHRAE, Ross & Baruzzini, Inc., St. Louis, MO

Seminar 2 - Steps toward Net Zero for the Marine Corps Logistics Base at Albany GA
•Chair: Alonzo Blalock, P.E., Member, Jacobs Engineering, Fort Worth, TX
•Step One: Addition of 31 MW PhotoVoltaic Facility at MCLB Albany William Houser, P.E., Georgia Power, Atlanta, GA
•Step Two: Installation of BTES system at MCLB Albany Chuck Hammock, P.E., Associate Member, Andrews, Hammock & Powel, Inc., Macon, GA
•Step Three: Maximizing by Retro-Commissioning Robert Bucey, P.E., Member, Jacobs, Dallas, TX

Winter 2018 Chicago
Seminar 1 - Campus Operators Reflect on Using Guideline 22 and Standard 90.1 for Chiller Plant Monitoring Track: Standards, Guidelines and Codes
•Chair: Dwayne Johnson, Trane
•University Campus Chiller Plants: ASHRAE Guideline 22 and Standard 184P in Operation - John Vucci,
•Healthcare Chiller Plants: ASHRAE 90.1 Chiller Plant Monitoring and Beyond - Tim Peglow, P.E

Seminar 44- The Best of “Engineer’s Notebook” 2nd Edition
•Chair: John Kuempel Jr., P.E.
•Building Automation System Control of Variable Air Volume Labs Steven T. Taylor, P.E., Fellow ASHRAE,
•Chillers and Boilers in the Same Room: A Cautionary Tale - Stephen W. Duda, P.E., BEAP, HBDP and HFDP, Fellow ASHRAE
•Energy Efficient Ventilation Systems for Labs - Daniel H. Nall, P.E., BEMP, CPMP and HBDP, Fellow Life Member
•Underground Piping Distribution Systems - Kent W. Peterson, P.E., BEAP, Presidential Fellow ASHRAE

Winter 2017 Las Vegas
The Best of “Engineer’s Notebook
•VAV Box Duct Design Steven T. Taylor, P.E., Fellow ASHRAE
•Reverse Return Reexamined Stephen W. Duda, P.E., BEAP, HBDP and HFDP, Fellow ASHRAE
•Waterside Economizers and Standard 90.1- Daniel Nall, P.E., BEMP and HBDP, Fellow Life Member,
•Improving Central Chilled Water System Performance - Kent Peterson, P.E., BEAP, Presidential Fellow ASHRAE

Annual 2016 St. Louis
Seminar 49 - New Look and Energy to a Federal Building in Houston Track: HVAC Systems and Equipment
•Chair: Alonzo Blalock, P.E.
•Designing the New Look - Thomas Shelton
•Planning Renovation of an Occupied Building - James Penland
•Upgrades to the HVAC, Electrical and Plumbing Systems - Gary Poole, P.E.
•We Taught the Old Dog a New Trick Kendall Waldie, P.E.

Winter 2016 Orlando
Seminar 57 - How Does the Criterion Engineer’s Role Affect the Design Build Contractor’s and Design Build Engineer’s Roles during All Phases of a Design Build Project?
•Chair: Alonzo Blalock, P.E., Member, Jacobs Engineering, Fort Worth, TX
•Criterion Engineer’s Role in a Design Build Project - Phillip M. Trafton
•Who Holds the Risk: The Criterion Engineer, the Design Build Contractor or the Design Build Engineer? John Kuempel, P.E
•How Can the Design/Build Engineer Effectively Work with the Criterion Engineer on a Design/Build Project? Jessica Mangler, P.E.

Annual 2015 Atlanta
Seminar 16 - There Is Gold in the Heartland at the Federal Courthouse in Cedar Rapids, Iowa
•Chair: Alonzo Blalock, P.E.
•An Overview of the Development and Construction of the New U.S. Courthouse in Cedar Rapids, Iowa – James Snedegar
•Selecting Systems to Produce Gold Level Performance - Lincoln Pearce, P.E.
•Commissioning for the Gold in All the Systems – Alonzo Blalock, P.E.
•The Cedar Rapids Courthouse Actual Energy Performance Has Exceeded All Expectations – John Nelson, P.E.

Winter 2015 - Seattle
Seminar 31 – Back to Basics towards Energy Efficient HVAC Design Track: Design of Energy and Water efficient Systems
•Chair: Charles E. Henck
•Back to Basics towards Energy Efficient HVAC Design – Nirmal Ram, P.Eng., Fellow ASHRAE

Seminar 44 - Air-Conditioning Research
•Chair: Reinhard Radermacher, Ph.D., Fellow ASHRAE
•Thermophysical Properties and Heat Transfer and Pressure Drop Performance Potentials of Hydrofluoro-Olefins, HydrochlorofluoroOlefins, and Their Blends - J. Steven Brown, Ph.D., P.E., Fellow , Claudio Zilio, Ph.D. , Riccardo Brignoli, Ph.D. and Alberto Cavallini, Ph.D.
•An Experimental and Computational Study of Approach Air Distribution for Slanted and a-Shaped Finned-Tube Heat Exchangers - David Yashar, Ph.D., Piotr Domanski, Ph.D., Fellow ASHRAE and Honghyun Cho, Ph.D.
•Evaluation of the Energy Performance and Thermal Comfort of an Air Conditioner with Temperature and Humidity Controls in a Cooling Season - Honjun Moon, Ph.D.

Summer 2014 - Seattle, WA
Seminar 8 - Case Studies of Energy Reduction in Existing Buildings: Lessons Learned on How Involving Owners and Operators in Design and Execution Creates Successful Long Term Results
  •Chair: Romero
  •Saving Energy in the Electric Company Headquarters Building, Rebuilding HVAC Systems While Occupied - Kuempel
  •Commissioning and Maintaining a Building during a Floor-by-Floor Renovation - Nicklas
  •Retrofits for Laboratory Buildings - Cramm
Summer 2013 - Denver, CO
Sky High Efficient Case Studies
  •Chair: Cramm
  •High Efficiency, Direct-Indirect Cooling Application for High Performance Office Building (Trimble) - Madigan
  •High-Efficiency Ventilation Air Upgrade at Major Convention Facility - Duda
  •High Efficiency, High Profile Riverfront Restaurant HVAC Replacement Without Missing a Serving - Kuempel
Winter 2013 - Dallas, TX
Hydraulic Modeling
  •Chair: Klock
  •What Is Hydraulic Modeling? - Simmons
  •Hydraulic Modeling of a University Chilled Water System - Mikulin
Summer 2012 - San Antonio, TX
When Integrated Controls Are Not Integrated
  •Chair: Cramm
  •Case Studies: How We Got This Student Union Building Unified - Rimmer
  •Case Studies: City Hall Out of Control - Overview - McKew
  •Case Studies: Commissioning Finds Project without Control - Conlan
Winter 2012 - Chicago, IL
Case Studies: New Equipment & Applications to Improve Energy Efficiency
  •Chair: Cramm
  •Geothermal Upgraded to Heat Recovery Chiller and Variable Refrigerant Flow - Kuempel
  •Chilled Water Modeling and Energy Metering for an Existing Chilled Water System Saves Energy - McKew
  •Ground Source Central Plant Successes and Lessons Learned - Schwedler
Winter 2011 - Las Vegas, NV
HVAC Security-Lest We Forget
  •Chair: McKew
  •HVAC Security: Overview of ASHRAE Handbook Chapter - Cogley
  •The New ASHRAE Guideline 29 and Secure HVAC Design - Dobbs
  •Checklist Approaches to HVAC Security - Campbell


Technical Committees are responsible for identifying research topics, proposing research projects, selecting bidders, and monitoring research projects funded by ASHRAE. Information about their specific research program is discussed at each TC meeting and at the TC’s Research Subcommittee meeting.

Coming soon!


ASHRAE writes standards for the purpose of establishing consensus for: 1) methods of test for use in commerce and 2) performance criteria for use as facilitators with which to guide the industry. ASHRAE publishes the following three types of voluntary consensus standards: Method of Measurement or Test (MOT), Standard Design and Standard Practice. ASHRAE does not write rating standards unless a suitable rating standard will not otherwise be available. ASHRAE is accredited by the American National Standards Institute (ANSI) and follows ANSI's requirements for due process and standards development. Standards may be purchased at the ASHRAE Bookstore.

TC 9.1 is cognizant or co-cognizant for the following guidelines and standard:

ASHRAE Guideline 0: The Commissioning Process

ASHRAE Guideline 16: Selecting Outdoor, Return, and Relief Dampers for Air-Side Economizer Systems

ASHRAE Guideline 22: Instrumentation for Monitoring Central Chilled Water Plant Efficiency

ANSI/ASHRAE Standard 15: Safety Standard for Refrigeration Systems [co-cognizant]

Other Activities

TIP: If MTG involvement add here otherwise leave blank.



ASHRAE Technical FAQs are provided as a service to ASHRAE members, users of ASHRAE publications, and the general public. While every effort has been made to ensure their accuracy and reliability, they are advisory and provided for informational purposes only, and in many cases represent only one person’s view. They are not intended and should not be relied on as an official statement of ASHRAE. Technical questions not addressed may be submitted to the ASHRAE Technical Services department at