Transportation Air Conditioning
ASHRAE Technical Committee 9.3

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 9.3 is responsible for the following Handbook Chapters:

HVAC Applications: Automobiles
Thermal systems in automobiles (HVAC, engine cooling, transmission, power steering) have significant energy requirements that can adversely affect vehicle performance. New and innovative approaches are required to provide the customer the desired comfort in an energy-efficient way. In recent years, efficiency of the thermal systems has increased significantly compared to systems used in the early to mid-1990s. Providing thermal comfort in an energy-efficient way has challenged the automotive industry to search for innovative approaches to thermal management. Hence, managing flows of heat, refrigerant, coolant, oil, and air is extremely important because it directly affects system performance under the full range of operating conditions. This creates significant engineering challenges in cabin and underhood thermal management. Optimization of the components and the system is required to fully understand the components’ effects on the system. Thus, modeling the components and the system is essential for performance predictions. Simulation of thermal systems is becoming an essential tool in the development phase of projects. Durability and reliability are also important factors in design of these systems.

HVAC Applications: Mass Transit
This chapter describes air-conditioning and heating systems for buses, rail cars, and fixed-guideway vehicles that transport large numbers of people, often in crowded conditions. Air-conditioning systems for these vehicles generally use commercial components, but are packaged specifically for each application, often integral with the styling. Weight, envelope, power consumption, maintainability, and reliability are important factors. Power sources may be electrical (ac or dc), engine crankshaft, compressed air, or hydraulic. These sources are often limited, variable, and interruptible. Characteristics specific to each application are discussed in the following sections. Design aspects common to all mass-transit HVAC systems include passenger comfort (ventilation, thermal comfort, air quality, expectation) and thermal load analysis (passenger dynamic metabolic rate, solar loading, infiltration, multiple climates, vehicle velocity, and, in urban applications, rapid interior load change).

HVAC Applications: Aircraft
Environmental control system (ECS) is a generic term used in the aircraft industry for the systems and equipment associated with ventilation, heating, cooling, humidity/contamination control, and pressurization in the occupied compartments, cargo compartments, and electronic equipment bays. The term ECS often encompasses other functions such as windshield defog, airfoil anti-ice, oxygen systems, and other pneumatic demands. The regulatory or design requirements of these related functions are not covered in this chapter.

HVAC Applications: Ships
This chapter covers air conditioning for oceangoing surface vessels, including naval ships, commercial vessels, fishing boats, luxury liners, pleasure craft, and inland and coastal boats, as well as oil rigs. Although the general principles of air conditioning for land installations also apply to marine applications, factors such as weight, size, fire protection, smoke control, and corrosion resistance take on greater importance, and new factors (e.g., tolerance for pitch and roll, shipboard vibration, watertightness) come into play.

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

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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 and are available under Virtual Conference Access.  Recordings may also be available by DVDs.  Products available from the most recent conference may be found in the Bookstore.

TC 9.3 Sponsored Programs:

February 2025 - Orlando

Tuesday, February 11, 9:45 AM - 10:45 AM - SEMINAR 38 (BASIC)

Challenges and Opportunities with Low-GWP Refrigerants in Transportation Applications

Chair: Riley B Barta, PhD, Associate, Purdue University, W LAFAYETTE, IN

This seminar focuses on the unique challenges faced by the transportation sector due to the transition to lower-GWP refrigerants. Both air conditioning and refrigeration will be considered, and automotive, refrigerated trailers, mass transit and passenger rail applications will be presented. Motivated by the continued GWP phase down, the advancements with flammable, high pressure and mixture refrigerants in the context of transportation will be highlighted and discussed from industry and academic perspectives.

1. Lower GWP Refrigerant Alternatives for Transport Refrigeration Alexander Schmig, Full Member, Trane Technologies, La Crosse, WI

2. Sustainable Air Conditioning System Using Transcritical CO2 for High-Speed Rail Applications Stefan Elbel, Full Member, TU Berlin, Urbana, IL

3. Low GWP Alternatives for R410A, R407C and R134a in Air Conditioning System for Mass Transit Applications Nilesh Purohit, PhD, Associate, Honeywell, MINNEAPOLIS, MN

February 2023 - Atlanta

Wednesday, February 8, 8:00 AM - 9:30 AM - SEMINAR 54 (INTERMEDIATE)

Automobile and Aircraft Cabin Air Quality and Passengers' Wellbeing: Implications for Ventilation

Summary:  Indoor CO2 and volatile organic compounds (VOC), together with occupant comfort, well-being, physiology, health and cognitive performance are influenced by ventilation. CO2 levels have been extensively used as a proxy for air quality in smart buildings ventilation and this approach is finding its way into aircraft cabins, automobiles and other means of transportation. Future control algorithms are focused on implementation of VOC levels and effects combined with environmental conditions. Enhanced control of ventilation system on aircraft, other means of transportation and buildings is aimed at improved persons' well-being, performance as well as at environmental and economic benefits.

Chair: Florian Mayer, Dr.

1. Recent Evidence on the Effects of CO2, Human Bioeffluents and Ventilation on Human Performance and Implications for Built Environment and Other Means of Transportation, Pawel Wargocki, Dr., Technical University of Denmark, DTU SUSTAIN, Kongens Lyngby, Denmark

2. Economic Viability of Adaptive Environmental Control System Designs, Richard Fox, Dr., Aircraft Environmental Solutions Inc., San Tan Valley, AZ

3. The Effect of Different p, CO2, VOCs on Aircraft Passenger Comfort and Cognitive Performance, Florian Mayer, Dr., Fraunhofer IBP, Valley, Germany

4. Control Strategy to Limit Build-up of Cabin CO2 Concentrations in Automobiles as a Function of Number of Occupants and Vehicle Speed, Gursaran Mathur, PE, Highly-Marelli North America, Farmington Hills, MI

February 2021 - Virtual

Tuesday, February 9, 3:00 PM - 4:20 PM - SEMINAR 9 (INTERMEDIATE)

Mass Transit Ventilation and Infectious Diseases: Transmission and Countermeasures WITH LIVE Q&A

Chair: Gursaran Mathur, Marelli North America, Farmington Hills, MI

Vehicles instrument panel surface can become contaminated by the front occupants by breathing, talking and coughing. Air conditioning vent outlet airflow will pull air from the panel surface mixing it with potential contaminated air and deliver towards the occupants. Hence, it is necessary to ensure we have virus mitigating strategies to effectively remove viruses from the cabin from automobiles. This seminar consists of technical presentations outlining how the viruses spread in automotive and aircraft cabins using CFD analysis, experimental studies with new hardware designs to eliminate viruses from the automotive cabin; and ASHRAE guidelines to address COVID-19. Learning Objectives: 1. Viruses spread within an automobile, mass transit and aircraft cabins and impact on occupants. 2. Understand the mechanism of airborne infectious disease transmission 3. Overview of numerical and experimental studies on spread of the viruses within the control volume along with new hardware design to eliminate these viruses 4. Review of ASHRAE TC 9.3 guidelines for addressing COVID-19 in mass transit 5. better understand exposure effects of social distanced seating in aircraft cabins 6. analyze the results of tracer studies in aircraft cabins 7. Describe the ASHRAE Guidelines for Mass Transit. 8. Explain the factors affecting safety of using mass transit in a period of Covid 19 pandemic.

1. COVID-19 Transmission Risk Reduction through Social Distanced Seating in Aircraft Cabins James Bennett, Ph.D., Member, CDC/NIOSH, Cincinnati, OH

2. Recommendations to Minimize the Risk of COVID-19 Spread in Marine Applications Augusto SanCristobal, Member, Bronswerk Group, Montreal, QC, Canada

3. Elimination of Viruses from Automobile Cabins Gursaran Mathur, Marelli North America, Farmington Hills, MI

4. ASHRAE’s COVID-19 Guidance Document for Mass Transit Donald LeBlanc, P.Eng., Member, National Research Council of Canada, Ottawa, ON, Canada

February 2020 - Orlando

Sunday, February 2, 1:30 PM - 3:00 PM - SEMINAR 17 (INTERMEDIATE)

Aircraft Cabin Air Quality, Airborne Disease Exposures and Ventilation Controls

Chair: Liangzhu (Leon) Wang, Ph.D., P.E., Member, Concordia University, Montreal, QC, Canada

1. A New Personalized Ventilation System for Airliner Cabins Qingyan Chen, Ph.D., Life Member, Purdue University, West Lafayette, IN

2. Airborne Disease Exposure and Tracer Data in Aircraft Cabin James Bennett, Ph.D., Member, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, U.S. DHHS, Cincinnati, OH

3. Transient Airfl ow and Particle Transmission from Aircraft Lavatories Tengfei Zhang, Dalian University of Technology, Dalian, China

4. Experimental Measurements and Large Eddy Simulation of Particle Deposition Distribution Around Aircraft Cabin Supply Air Nozzles Chun Chen, Ph.D., Associate Member, The Chinese University of Hong Kong, Hong Kong, China

5. Analyzing the Symmetry of Airborne Pathogens Dispersion in Airplane Cabins M.H. Hosni, Ph.D., Fellow ASHRAE, Kansas State University, Manhattan, KS

January 2016 - Orlando

Tuesday, January 26, 8:00 AM - 9:30 AM - SEMINAR 37 (INTERMEDIATE)

Best Practices in Manufacturing, Field Installation and Servicing Refrigeration and Air-Conditioning Systems 

Chair: Georgi Kazachki, Ph.D., Fellow ASHRAE, Dayton Phoinix Group, Inc., Dayton, OH

The efficient, reliable and environmentally sound operation of refrigeration and air-conditioning systems depends to a large extent on the presence of moisture, non-condensables, contaminants and refrigerant leaks. Good practices have been established over the years, yet time and cost-reduction pressures often lead to questioning some of these practices, such as minimizing component exposure to ambient before assembly and installation, brazing with inert gas, leak elimination and deep evacuation before charging with the proper amount of fresh refrigerant. This seminar illustrates the best practices with respect to the system chemistry and material compatibility in refrigeration systems.

1. Using a Protective Atmosphere during Brazing of HVAC and Refrigeration Tubing and Its Effect on the Formation of System Contamination, Marc Scancarello, P.E., Member, Emerson Climate Technologies, Inc., Sidney, OH

2. Effects of Process Lubricants for Fin Stamping, Tube Bending and Construction of HVAC&R Systems, Robert Turner, Metalloid Corporation, Sturgis, MI

3. Impact of Refrigeration System Commissioning on Energy Usage and System Reliability, Michael Collins, Carlyle Compressor Company, Syracuse, NY

4. Servicing AC and Refrigeration Systems for Efficiency and Reliability, Robert Scorupsky, P.E., Member, Daikin America, Inc., New Brunswick, NJ

January 2013 - Dallas

Sunday, January 27 - SEMINAR 1 (BASIC)

Ask Not What Your Industrial Committee Can Do For You - Ask What You Can Do For Your Industrial Committee

Chair: Michael Connor, P.E., Member, Connor Engineering Solutions, Alpharetta, GA

ASHRAE’s Industrial and Transportation Committees are concerned with standards, handbook chapters and other publications and programs for environmental systems in industrial facilities. These are among the oldest standing technical committees in our society. Industrial and Transportation facilities also offer the greatest potential for energy conservation and resource conservation. According to the US Department of Energy, the Industrial and Transportation sectors of our economy are responsible for 59% of the total energy consumed in the USA (2010). Being “green” in this area has always been the custom as it represents good business: it lowers the cost of goods sold and increases the bottom line. This session will introduce ASHRAE’s Industrial and Transportation Technical Committees, their activities and the latest green efforts in these sectors. This session also discusses “hot button” issues facing these committees.

1. TC 5.8 Industrial Ventilation Kenneth R. Mead, Ph.D., P.E., Member, CDC - National Institute for Occupational Safety and Health (NIOSH), Cincinnati, OH

2. TC 5.9 Enclosed Vehicular Facilities Greg Sanchez, P.E., Member, MTA New York City Transit, New York, NY

3. TC 9.2 Industrial Air Conditioning Michael Connor, P.E., Member, Connor Engineering Solutions, Alpharetta, GA

4. TC 9.3 Transportation Air Conditioning Richard Fox, Member, Honeywell Aerospace, Tempe, AZ

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.

The Research Subcommittee is responsible for pushing forward ideas and areas that advance the art and science of Transportation Air Conditioning.  These programs require research by scientist that provides conclusions substantiated with fact.  Research money from the ASHRAE Research Foundation is used to fund this research.

ASHRAE training presentation: "How to Write a Successful RTAR or Work Statement"

TC 9.3 Current Research Projects:

There are no active research projects sponsored by TC 9.3.

TC 9.3 Completed Research Projects:

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ASHRAE members have free access to research project final reports. Non-ASHRAE members can purchase research reports for $30 per article from the ASHRAE Bookstore found at this link.

RP-1830: EXPERIMENTAL CHARACTERIZATION OF AIRCRAFT BLEED AIR PARTICULATE CONTAMINATION (2022)

RP-1306: INCIDENT RESPONSE MONITORING TECHNOLOGIES FOR AIRCRAFT CABIN AIR QUALITY (2014)

ASHRAE contracted the Netherlands Organization for Applied Scientific Research for carrying out the study registered under the Research Proposal 1306-TRP. The work commissioned is to establish a technology review to identify novel candidate technologies or methods for identifying and quantifying aircraft power system contaminants, such as organophosphate esters, in the cabin air during unanticipated adverse incidents and to rank available methodologies for suitability of use, along with supporting rationale.

Subsequently to perform performance testing of the two methods ranked highest by evaluating the emitted components and the performance characteristics under laboratory conditions. Peer-reviewed literature, including but not limited to scientific and technical journals was searched on the above mentioned problems. Beside these journals, also gray literature was reviewed and included in the discussion.

RP-1262 (PART 2): RELATE AIR QUALITY AND OTHER FACTORS TO COMFORT AND HEALTH SYMPTOMS REPORTED BY PASSENGERS AND CREW ON COMMERCIAL TRANSPORT AIRCRAFT (2020)

This study is part of an ASHRAE program aimed at investigating the potential link between perceived health symptoms and discomfort on one hand, and aircraft cabin environmental conditions and human factors on the other. Such data were called for in the NRC report to Congress (2002), and are needed to support ASHRAE’s standard setting process. Part I of the project has used the results from past studies and a literature review to guide the development of a measurement system and protocol, and a survey tool. These tools were then pilot tested and validated on four commercial aircraft flights. Part II, which will be under separate contract, will utilize the validated measurement and survey tools to collect data on a statistical sample of aircraft types and routings, and relate the health and comfort survey results from passengers and crew to the air quality and environmental variables observed.

RP-1262 (PART 1): RELATE AIR QUALITY AND OTHER FACTORS TO COMFORT AND HEALTH SYMPTOMS REPORTED BY PASSENGERS AND CREW ON COMMERCIAL TRANSPORT AIRCRAFT (2004)

This study is part of an ASHRAE program aimed at investigating the potential link between perceived health symptoms and discomfort on one hand, and aircraft cabin environmental conditions and human factors on the other. Such data were called for in the NRC report to Congress (2002), and are needed to support ASHRAE’s standard setting process. Part I of the project has used the results from past studies and a literature review to guide the development of a measurement system and protocol, and a survey tool. These tools were then pilot tested and validated on four commercial aircraft flights. Part II, which will be under separate contract, will utilize the validated measurement and survey tools to collect data on a statistical sample of aircraft types and routings, and relate the health and comfort survey results from passengers and crew to the air quality and environmental variables observed.

In the Part I study reported here, three carry-on instrument packages were developed. Two were suitcases designed to fit under passenger seats. The third package was used to make spatial measurements of air speed, temperature, and noise throughout the passenger cabin. The underseat instruments measured temperature, relative humidity, light intensity, motion (acceleration), ozone, carbon dioxide, carbon monoxide, fine particulate matter, volatile organic compounds and semivolatile organic compounds. The instruments are battery powered, independent of aircraft systems, and can be installed and put into operation in 5-10 minutes. The instruments were tested for electromagnetic interference and certified for use aboard commercial aircraft. Two interrelated questionnaires were developed to assess passenger and crew perceptions of health and comfort in the cabin environment.

RP-978:  INTERACTION OF ROOM AIR MOTION AND THE HUMAN BODY IN CONFINED SPACES (2000)

This research is needed to develop models of air motion in confined spaces. These models will in turn be used for the design of diffusers, for determining air inlet and exhaust locations, and for studying air quality and contaminant transport in confined/high density environments. Aircraft manufacturers and operators (airlines) are in particular need of this information. Use will not be limited to this particular group, however, as it will also be of use in any application where there are high occupant densities in confined spaces. The objective of this research project is to check the allowable air speed limits to avoid draft prescribed in the standard 55-1992 when people are inside the summer comfort zone, investigate whether stated preferences for higher air velocities found in recent ASHRAE field studies can be verified when people are exposed to such higher velocities under controlled conditions, and verify whether combinations of elevated temperatures and air velocities, as described in Figure 3 of Standard 55-92, are subjectively acceptable. Also, compare comfort responses to such combinations with those achieved with low velocity and moderate temperatures within the Standard 55-1992's summer comfort zone.

RP-959: DETERMINE AIRCRAFT SUPPLY AIR CONTAMINANTS IN THE ENGINE BLEED AIR SUPPLY SYSTEM ON COMMERCIAL AIRCRAFT (2000)

ASHRAE has approved the formation of the Standard 161 committee with the charter to derive an air quality standard specifically for commercial airplanes carrying 19 or more persons. This committee will determine the quality of air necessary to ensure the health, safety, and comfort of the crew and passengers on board commercial airliners. Because of the nature of airliner cabins and the environment in which they operate, many factors come into play which affect cabin air quality. Generally these factors include altitude, geographic location, environmental contaminants present in the area of aircraft operation on the ground, and the condition of the machinery providing and conditioning the air supply. The objective of this research project is to identify potential supply system contaminants, which may be generated by aircraft propulsion engines, and APU's, or ingested from aircraft systems. It will provide information on contaminants produced by aircraft systems with high engine operating hours and cycles. It will provide information on the effect of operating at cruise power at altitude on contaminant levels. It will also identify the extent to which system generated contaminants pass through the environmental control system into the cabin of the aircraft.

RP-957: RELATE AIR QUALITY AND OTHER FACTORS TO SYMPTOMS REPORTED BY PASSENGERS AND CREW ON COMMERCIAL TRANSPORT CATEGORY AIRCRAFT (1999)

The study has the following four distinct parts:

-Conduct a literature search to determine possible causal factors that may contribute to reported symptoms and help differentiate between symptoms caused by air quality from those caused by other factors;

-Prepare a comfort questionnaire (using an existing questionnaire as an outline) and use it to poll passengers and crew on flights where air quality testing is being conducted;

-Develop a testing protocol to measure aircraft cabin contaminants and environmental parameters; and

-Conduct air quality monitoring on the ground and during flight on eight commercial flights.

A unique aspect of this study was the measurement of cabin contaminants and environmental parameters in parallel with the administration of comfort questionnaires to passengers and crewmembers. The objective of the project, because of limited funds, was not to collect large amounts of data, whereby significant correlations between contaminant levels and passenger responses could be deduced. But rather, the objective was to develop an air quality testing protocol and comfort questionnaire to determine if this type of research could be successful, and to make recommendations that could enhance the overall effectiveness of future studies.

RP-619: CHARACTER OF THERMAL LOADS IMPOSED BY MASS RAPID TRANSIT PASSENGERS ON VEHICLES ENVIRONMENT CONTROL SYSTEMS (1993)

Available design information for thermal loads generated by people are based on steady state data. An hour or more can be required for a person to reach a thermal steady state after entering a new environment and/or changing activity. This long response time makes steady state information of limited use in the design of environmental control systems for mass transit vehicles where large numbers of people enter the vehicle at one time and/or where there is a rapid turnover of passengers. This paper presents the results of ASHRAE research project 619-KP which addressed this problem. To obtain quantitative data describing the dynamic nature of the heat and moisture people dissipate to their surroundings, experiments were conducted in a calorimeter capable of holding ten people. Test subjects were exposed to controlled conditions and activity levels in a separate environmental chamber prior to entering the calorimeter. Once in the calorimeter, the heat dissipation and moisture dissipation from the subjects to the calorimeter environment were measured on a continuous basis. Twenty such experiments were conducted. A computer simulation model which predicts dynamic sensible and latent loads generated by people was also developed. The model is based on a modified version of the Gagge two-node model which simulates the thermal transients in the human body. The modified model includes a transient simulation of heat and moisture flows through clothing and moisture accumulation in clothing. These factors both play an important role in determining the mix of sensible and latent heat dissipation, as well as the total heat dissipation, during transients. The final model was validated with the experimental data and now provides a tool for designers to predict the size and nature of human generated thermal loads in a wide variety of transient situations.

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 9.3 is cognizant or co-cognizant for the following guidelines and standards:

Gdl. 23: Guideline for the Design and Application of Heating, Ventilation and Air Conditioning Equipment for Rail Passenger Vehicles

Gdl. 28: Air Quality Within Commercial Aircraft

Std. 26: Mechanical Refrigeration and Air Conditioning Installations Aboard Ship  (TC10.6 lead)

Std. 161: Air Quality Within Commercial Aircraft

TIP: If MTG involvement add here otherwise leave blank.

Include other activities, such as MTG involvement, into this section.

TIP: If MTG involvement add here otherwise leave blank.

Mass Transit/Rail

                June 2017 Mass Transit Meeting Minutes

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 tse@ashrae.net.

TC 9.3 is responsible for the following FAQs:

What is ASHRAE's standard for aircraft air quality?
Where can I get information on the options for changing the refrigerant used in my automobile air conditioner system?