Understanding Energy Codes and the Role of Air Barriers in Building Performance

What Design Professionals Should Know About Energy Codes and Air Barriers

Energy codes have become a defining influence in modern construction. For architects, engineers and contractors, these codes shape nearly every design and material choice that affects a building’s energy performance. From the roofline to the foundation, each component of the building envelope contributes to overall efficiency and occupant comfort.

Among these components, the air barrier system plays one of the most significant roles. By controlling the movement of air, moisture and heat through the envelope, air barriers help buildings meet increasingly stringent energy code requirements.

Why Energy Codes Matter to Building Performance

Energy codes were developed to reduce energy consumption in buildings, which account for roughly 40 percent of total energy use in the United States. Codes establish minimum performance standards for the building envelope, lighting and mechanical systems. They ensure that new construction and major renovations achieve measurable reductions in heating and cooling loads.

The International Energy Conservation Code (IECC) and ASHRAE 90.1 are the two primary standards guiding energy performance in commercial buildings. Most states base their energy code on one or both, often with regional amendments that account for local climate conditions.

While these codes have been in place for decades, each update introduces higher efficiency targets and more rigorous testing requirements. The 2021 IECC, for example, emphasized tighter air-sealing standards and greater accountability through whole-building air-leakage testing.

The 2024 IECC builds on that foundation focusing on higher performance and greater accountability. Notable changes include stricter air-barrier and envelope testing requirements, expanded demand-control ventilation, new humidity control limits and lower thresholds for daylighting controls and sub-metering. The code also adds renewable-energy requirements, updates the additional efficiency credit system, and introduces a new Total System Performance Ratio (TSPR) compliance path. Together, these changes aim to improve building efficiency, streamline verification and reduce overall energy use.

By improving the airtightness and thermal performance of the building envelope, these stricter codes help reduce energy waste, lower operating costs and improve occupant comfort while contributing to national sustainability goals.

Air Leakage and Energy Loss in Commercial Buildings

Air leakage is a leading cause of energy waste in buildings. Even small gaps around penetrations, joints and transitions can allow conditioned air to escape and unconditioned air to enter. According to the U. S. Department of Energy (DOE), infiltration accounts for 6% of the energy use and $11 billion in energy cost for U. S. commercial buildings.

In cold climates, leakage results in heat loss and condensation inside the wall assembly. In hot and humid regions, it allows moisture-laden air to infiltrate, raising indoor humidity and increasing the load on HVAC systems.

Reducing these uncontrolled pathways is the goal of the air barrier system. Properly designed and installed, the air barrier controls airflow through the envelope, creating a continuous layer of protection that improves thermal performance and indoor air quality.

Energy Code Requirements for Continuous Air Barriers

Energy codes now require most commercial buildings to include a continuous air barrier system. The IECC specifies that the barrier must:

• Enclose the entire building envelope, including roofs, walls, and below-grade assemblies.
• Be continuous across joints, seams, and transitions.
• Have an air leakage rate of less than 0.004 cfm/ft² at 1.57 psf, when tested per ASTM E2357, E779 or E1827.

ASHRAE 90.1 includes similar requirements, focusing on material performance and continuity. These provisions ensure that the barrier functions as an integrated system, not a collection of unrelated components.

Design professionals must identify the air barrier layer clearly in drawings and specifications. They also must verify compatibility among materials and coordinate trades to maintain continuity throughout construction.

Integrating Air, Vapor and Water Barriers in the Building Envelope

The air barrier is one layer within a larger envelope assembly that also includes insulation, vapor control and water-resistive components. Its purpose is distinct but interdependent. A high-performance building envelope depends on the balance of these layers working together.

• Air barriers control air leakage that drives energy loss and moisture transport.
• Vapor retarders control diffusion of water vapor through materials.
• Water-resistive barriers (WRBs) protect against liquid water intrusion.
• Thermal insulation limits air flow through the envelope.

If one layer fails, the others must compensate, often at the expense of overall performance. For example, if the air barrier isn’t continuous, humid air may infiltrate the wall cavity and condense on cold surfaces, compromising insulation and increasing energy use.

Henry® Building Envelope Systems® are designed with this interdependence in mind. Henry products integrate air, vapor and water control layers into compatible systems that meet or exceed the latest energy code standards.

Advances in Air Barrier Technology and System Design

The idea of controlling air leakage is not new, but the technology has advanced significantly in the past two decades. Early barriers were often vapor-tight membranes that limited both air and vapor movement. As understanding of building science grew, manufacturers developed systems that balance permeability and airtightness to suit different climate zones and wall types.

A pioneer in the building industry with roots dating back to the 1930’s, Henry® helped pioneer commercial construction with the introduction of air barriers. Our complete portfolio provides design pros with the ultimate in both performance and design flexibility including:

• Henry® Blueskin VP160: A self-adhered, vapor-permeable sheet membrane that fully adheres to wall substrates without a mechanical attachment.
• Barritech VP: A fluid-applied, fire-resistant membrane for use in wall assemblies requiring NFPA 285.
• Henry® Air-Bloc® All-Weather STPE: A spray-applied, single-component membrane designed for adhesion in variable temperatures and humidity.

These systems are tested to meet ASTM E2357 for air-leakage performance and support compliance with the 2021 IECC and ASHRAE 90.1 standards.

Choosing the Right Air and Vapor Barrier for Your Climate Zone

Energy codes categorize the United States into eight primary climate zones, each with distinct temperature and moisture conditions. These zones influence how the air and vapor barrier layers are configured.

• Cold climates (Zones 6–8) typically require vapor-tight barriers on the warm side of the insulation to prevent interior moisture from condensing within the wall.
• Mixed climates (Zones 4–5) often benefit from vapor-permeable barriers that permits drying to both the interior and exterior walls.
• Hot-humid climates (Zones 1–3) focus on controlling exterior moisture intrusion and limiting inward vapor drive.

^{*The federal Department of Energy created the Climate-Specific Building Assemblies Tool to help builders select foundation, wall, and roof construction assemblies that support 2021 IECC and IRC 2021 requirements for thermal efficiency and condensation control.} 

Selecting the right combination of air and vapor control layers ensures compliance with code requirements and extends building service life. Henry technical representatives assist design teams in choosing the appropriate system for each region and assembly type.

Testing and Verification for Energy Code Compliance

Energy codes not only define performance targets but also emphasize verification. Whole-building air-leakage testing, conducted per ASTM E779 or E3158, measures how well the envelope performs once construction is complete.

Passing results require coordinated effort among all trades. Penetrations, window-to-wall transitions and roof-to-wall transitions must be sealed and inspected before testing. Failure to achieve the target leakage rate can result in costly rework or delayed occupancy.

Henry supports contractors through training, field testing, and technical support to help ensure installation quality. A well-installed system is as important as the membrane itself.

Understanding Regional Energy Code Adoption and Climate Requirements

Energy codes are not adopted uniformly across the United States. Each state or municipality determines which version of the IECC or ASHRAE 90.1 to follow and may modify specific requirements to suit regional climate conditions and building practices.

For this reason, design teams must confirm the applicable code early in the project. The Building America Solution Center, developed by the Pacific Northwest National Laboratory (PNNL), provides up-to-date information on current energy-code adoption and guidance for compliant assemblies by climate zone.

Understanding these variations helps architects and contractors select appropriate materials, specify compliant air-barrier systems and document performance accurately to avoid costly changes or delays later in the project.

How Energy Codes Improve Building Efficiency and Indoor Comfort

Energy codes have effects that extend beyond compliance. They shape how buildings contribute to community resilience, environmental sustainability and occupant health.

A tighter envelope reduces energy use and greenhouse-gas emissions, but it also improves comfort and indoor environmental quality. Controlled airflow prevents drafts, temperature swings and condensation, while consistent humidity levels reduce the risk of mold and material degradation.

As codes continue to evolve, building performance expectations will rise. Future versions of the IECC and ASHRAE 90.1 are expected to include even more rigorous targets for whole-building air-leakage and energy intensity.

Designing Beyond Code: Achieving High-Performance Building Envelopes

Meeting the minimum code is no longer the end goal for most design teams. Owners increasingly want to exceed baseline standards through high-performance construction, net-zero design and building-enclosure commissioning.

Specifying tested and compatible air barrier systems is an essential part of this shift. Fully integrated solutions such as Henry Building Envelope Systems support not only code compliance but also long-term performance.

When systems are designed and installed as part of a coordinated building-envelope strategy, the benefits are tangible: lower operating costs, improved durability, and better occupant comfort.

Schedule a meeting today to see how Henry’s complete portfolio of solutions can help you achieve energy-code compliance and high-performance results.