Testing! Testing! Key ASHRAE and ASTM Standards for Commercial Air Barriers

 In part I, we looked at IECC codes applicable to air barriers. In part II, we will explore ASHRAE and ASTM standards which concern energy standards and material testing. 

ASHRAE and Air Barriers

ASHRAE Standard 90.1 is the primary energy standard governing commercial and non-low-rise residential construction in the United States. The current edition — ASHRAE 90.1-2022 — was published in December 2022, with states required to certify adoption by early 2026. One of its most significant envelope updates is a tightening of the whole-building air leakage limit from 0.40 cfm/ft² under 90.1-2019 to 0.35 cfm/ft² at 75 Pa, and for the first time, mandatory independent third-party air leakage testing is now required.

This builds on a trajectory established in earlier editions: both 90.1-2016 and 90.1-2019 already required a continuous air barrier across all new construction except in Climate Zone 2B. The latest edition, 90.1-2022, continues and strengthens those requirements. 

This standard defines a Continuous Air Barrier as "the combination of interconnected materials, assemblies, and sealed joints and components of the building envelope that minimize air leakage into or out of the building envelope." Design requirements include detailed component, joint, and penetration specifications, with the air barrier system extending over all surfaces including the roof, and the ability to withstand pressures from wind, mechanical, and stack effects. Installation requirements address sealed junctions between walls and roofs or ceilings, penetrations at roofs, walls, and floors, and joints and seams at interfaces and changes in plane. 

At the state level, New York has gone further still — adopting NYS ASHRAE 90.1-2025, a state-specific edition based on the national 90.1-2022 standard with New York-specific amendments, which became effective December 31, 2025.[1]

ASTM: Material Level Testing

ASTM E2178-21a measures the air permeance of individual building materials — any material must achieve less than 0.004 cfm/ft² at 75 Pa to qualify as an air barrier material

ASTM: Assembly Level Testing

It is important to note that assembly test results are intended for comparison purposes only and do not alone represent real installed field performance.

• ASTM E2357-23a is currently listed as the active standard for determining air leakage rates of air barrier assemblies
• ASTM D8052 covers roof system air barrier assemblies

ASTM: Whole-Building Testing

• ASTM E3158-24 is the primary method for large or multizone commercial buildings and is referenced directly by the 2024 IECC
• ASTM E1827-22 using an orifice blower door is an accepted alternate method
• ASTM E779-19 using fan pressurization is a third accepted method under the 2024 IECC and ASHRAE 90.1-2022[2]

At the assembly level, ASTM E2357 remains the most widely used test for commercial wall air barrier systems, establishing a comparison benchmark of 0.04 cfm/ft² at 75 Pa — but it's critical to understand that assembly test results reflect controlled lab conditions, not real-world installed performance. That gap is exactly what Whole Building Airtightness Testing (WBAT) is designed to close. By inducing a pressure differential across the entire building envelope and measuring the actual rate of air leakage, WBAT captures cumulative leakage at transitions, penetrations, and interfaces that component-level tests simply cannot detect. 

The 2024 IECC accepts three test methods for whole-building verification: ASTM E3158-24 for large or multizone commercial buildings, ASTM E779-19 using fan pressurization, and ASTM E1827-22 using an orifice blower door. 

And finally…

Come back for our final blog focusing on what these standards mean for air barriers in construction and how this impacts all trades.