Building Materials and Building Envelope Performance
ASHRAE Technical Committee 4.4

Scope of TC 4.4

TC 4.4 is concerned with the requirements and overall performance of the building envelope as it relates to: 1) heat, air and moisture related properties of building materials 2) fundamental heat, air and moisture transport processes of assemblies; 3) interactions with interior conditions and HVAC systems. In addition, TC 4.4 is concerned with the properties of materials used in mechanical systems to control heat and moisture flows.


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:

Heat, Air, and Moisture Control in Building Assemblies - Fundamentals
Proper design of space heating, cooling, and air-conditioning systems requires detailed knowledge of the building envelope’s overall heat, air, and moisture performance. This chapter discusses the fundamentals of combined heat, air, and moisture movement as it relates to the analysis and design of envelope assemblies. Guidance for designing mechanical systems is found in other chapters of the ASHRAE Handbook.

Heat, Air, and Moisture Control in Building Assemblies - Material Properties
This chapter contains material property data related to the thermal, air, and moisture performance of building assemblies. The information can be used in simplified calculation methods as applied in Chapter 27, or in software-based methods for transient solutions. Heat transfer under steady-state and transient conditions is covered in Chapter 4, and Chapter 25 discusses combined heat/air/moisture transport in building assemblies. For information on thermal insulation for mechanical systems, see Chapter 23. For information on insulation materials used in cryogenic or low-temperature applications, see Chapter 47 of the 2010 ASHRAE Handbook—Refrigeration. For properties of materials not typically used in building construction, see Chapter 33 of this volume.

Heat, Air, and Moisture Control - Examples
This chapter draws on Chapter 25’s fundamental information on heat, air and moisture transport in building assemblies, as well as Chapter 26’s material property data. Examples here demonstrate calculation of heat, moisture, and air transport in typical assemblies. For design guidance for common building envelope assemblies and conditions, see Chapter 44 of the 2011 ASHRAE Handbook—HVAC Applications.

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

This TC is responsible for the following chapter in the HVAC Applications Volume

Building Envelopes
Proper building envelope design requires knowledge of the physics governing building performance as well as of building materials and how they are assembled. This chapter provides practical information for designing new building envelopes and retrofits to existing envelopes, always with the notion that the envelope must work well in concert with the building’s surroundings and the HVAC system. The information can also be useful for those involved with building envelope investigation and analysis. This chapter was developed with the integrated design approach in mind and assumes that the architect, HVAC designer, building envelope designer, and others involved in envelope design and construction communicate and understand the interrelationships between the building enclosure and mechanical systems. Integrated design requires a clear statement of the owner’s project requirements (OPR) and design intent, and is described in greater detail in Chapter 58. That chapter may be used as a basis for finding common agreement among designers and engineers using the integrated design approach. The growing use of integrated design in project delivery highlights the building envelope as the principal site where architectural design and mechanical engineering meet.

The ASHRAE HVAC APPLICATIONS 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.

Programs sponsored by TC 4.4 at the Summer 2020 Virtual Conference

  • (Time and Date TBD): Off-Site Construction for Resilient Buildings: Getting the Details Right
  • (Time and Date TBD): Who Said Thermal Storage Has to be Only in Tanks? Thermal Storage in the Building Envelope
  • (Time and Date TBD): Design Considerations for Resilient Buildings
  • (Time and Date TBD): Back to the Future on High Efficiency Design and Operations



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.

Current Projects

1696-RP: Thermal, Moisture and Air Transport Property Values for New Building and Insulating Materials
PMS: A. McGowan (chair), S. Glass, A. Karagiozis, T. Weston
Contractor: RDH Building Science Laboratories; PI: C. Schumacher                                                                                                                Status: Three-year project began Sep. 1, 2015.

 1759-TRP: Impact of Air-Flow on Thermal Performance of Airspaces behind Cladding (Phase 1 of 2)
Authors: J. Crandell, J. Humble, D. Yarbrough
Status: X years project - expected start December 2018.
[TC 4.4 voted to approve WS at St. Louis meeting; forwarded to RAC Aug. 15, 2016.]

Work Statements

1718-WS: Development of a Method to Determine the Moisture Transport Properties of a Roof Shingle System under Real Conditions
Author: M. Kehrer
Status: WS under revision to address RAC comments.

 1730-WS: Research to Determine the Pressure Coefficients and Pressure Drop for Standard Venting Strategies and Components in Attic Spaces with Sloped Roofs
Authors: A. Fontanini and D. Roodvoets
Status: WS submitted. 


Potential Future Projects

Draft RTAR: Develop Performance Metric, and a Process for the Measurement, Evaluation and Prediction of Speech Privacy in High Performance Buildings
Author: K. Roy (TC 2.6)
Status: TC 4.4 voted to co-sponsor RTAR at St. Louis meeting

 New RTAR: Evaluating the Accuracy of Whole Building Energy Simulations by Comparison with Field Measurement Data
Author: S. O’Brien
Status: Draft RTAR under revision

Draft RTAR: Hygrothermal Properties of Aged Construction Materials
Author: S. Cornick/Neal Holcroft
Status: Draft RTAR under revision

Draft RTAR: Moisture Transfer in Building Materials at High Temperatures
Authors: S. Glass
Status: Draft RTAR on hold until results from WS-1718. 


Last Updated: January 7, 2019


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 cognizant for the following standard:
ANSI/ASHRAE Standard 160: Criteria for Moisture-Control Design Analysis in Buildings

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Other Activities

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


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

This TC is responsible for the following Frequently Asked Questions

What does ASHRAE recommend for ventilation of attics, basements, and crawl spaces? (16)
Where does ASHRAE recommend that a vapor barrier be installed in the wall? (17)
Should attics be ventilated? (75)
Should crawl spaces be ventilated? (76)