Transportation Air Conditioning
ASHRAE Technical Committee 9.3

Scope of TC 9.3

TC 9.3 is concerned with providing technical information regarding transportation air conditioning applications, including aerospace, rail, surface vehicles, and ships.

TC 9.3 has three transport-specific subcommittees to support its operations: Automotive, Marine, and Mass Transit.  Check the Home Page to learn when these committees meet.


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 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.


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.

TC 9.3 has the following on-going research project:

The principal aim of this research project is to relate perceptions of discomfort or health related symptoms of flight attendants and passengers to possible causal factors, including cabin and bleed air quality and other factors such as reduced air pressure, jet lag, inactivity, humidity, flight attendant duty schedule and fatigue, circadian rhythm, stress and noise.


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

Other Activities

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

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?