Thermodynamics and Psychrometrics
ASHRAE Technical Committee 1.1

Scope of TC 1.1

TC 1.1 is concerned with basic thermodynamic laws and property relationships, particularly as they are applied to processes involved in heating, ventilating, air conditioning, refrigeration, and related areas of environmental engineering. A second concern of the TC is the fundamental thermodynamic and transport relationships for air and water vapor mixtures, as used in the study, measurement, and calculation of psychrometric properties and processes.


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.

The Handbook can be purchased at the ASHRAE Bookstore by clicking on this link.

This TC is responsible for the following chapters in the Fundamentals Volume

Psychrometrics uses thermodynamic properties to analyze conditions and processes involving moist air. This chapter discusses perfect gas relations and their use in common heating, cooling, and humidity control problems. Formulas developed by Herrmann et al. (2009) may be used where greater precision is required.

Thermodynamics is the study of energy, its transformations, and its relation to states of matter. This chapter covers the application of thermodynamics to refrigeration cycles. The first part reviews the first and second laws of thermodynamics and presents methods for calculating thermodynamic properties. The second and third parts address compression and absorption refrigeration cycles, two common methods of thermal energy transfer.

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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.


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.

This TC is co-cognizant with TC 0801 and TC 0102 (lead) for the following standards:

ANSI/ASHRAE Standard 41.1: Standard Methods for Temperature Measurement
ASHRAE Standard 41.2: Standard Methods for Laboratory Air-Flow Measurement
ANSI/ASHRAE Standard 41.3: Standard Methods for Pressure Measurement
ANSI/ASHRAE Standard 41.4: Standard Methods for Proportion of Lubricant in Liquid Refrigerant Measurement
ANSI/ASHRAE Standard 41.6: Standard Methods for Humidity Measurement
ANSI/ASHRAE Standard 41.7: Method of Test for Measurement of Flow of Gas
ASHRAE 41.8: Standard Methods of Measurement of Flow of Liquids in Pipes Using Orifice Flowmeters
ANSI/ASHRAE Standard 41.9: Standard Methods for Volatile-Refrigerant Mass Flow Measurements Using Calorimeters
ANSI/ASHRAE Standard 41.10: Standard Methods for Refrigerant Mass Flow Measurement Using Flowmeters
ANSI/ASHRAE Standard 41.11: Standard Methods for Power Measurement

This TC is cognizant for the following proposed standard

Proposed Standard: SPC 213P: Method for Calculating Moist Air Thermodynamic Properties

Other Activities

TIP: If MTG involvement add here otherwise leave blank.

This TC participates in the following Multidisciplinary Task Group

MTG.LowGWP: Lower Global Warming Potential Alternative Refrigerants
This MTG is established to coordinate TC/TG/TRG technical activities to help transition the HVAC&R industry to sustainable lower Global Warming Potential (GWP) alternative refrigerants. The MTG will further request participation from US EPA and AHRI. The MTG responsibilities include suggestions for research, development and presentation of technical programs of all types on alternative lower GWP refrigerants, suggestions for Life Cycle Climate Performance (LCCP) systems evaluation for different applications, development of lower GWP solutions for different applications, and a special publication detailing aspects of LCCP applied to the HVAC&R fields. 


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