Energy codes now shape many of the material and system decisions made in commercial and high-rise residential construction. ANSI/ASHRAE/IES Standard 90.1 establishes minimum energy-efficiency requirements for covered sites, buildings, systems, and equipment. Rmax polyiso insulation can help an envelope assembly meet the thermal requirements established by ASHRAE 90.1.
The Impact of ASHRAE 90.1 on Energy Efficiency
Adherence to ANSI/ASHRAE/IES 90.1 directly influences a building’s energy use and operating costs. The standard governs key areas such as insulation, HVAC systems, lighting, and service water heating.
Actual performance depends on the complete design, construction quality, controls, and building operation. In climates with large seasonal temperature swings, poor insulation can place greater heating and cooling demands on the building.
What the Standard Covers
ASHRAE Standard 90.1 establishes minimum energy-efficiency requirements for most sites and buildings other than low-rise residential buildings. It applies to new buildings, new portions of buildings, and specified new systems and equipment in existing buildings. Properly selected energy-efficient insulation helps limit heat flow through opaque assemblies.
Building Systems Governed by ASHRAE 90.1
Envelope heat transfer, equipment efficiency, and lighting loads all affect the building’s modeled or calculated energy use.
Building Envelope
A well-insulated building envelope is central to minimizing heat transfer. Rmax polyiso insulation, with its high R-value per inch, can help an approved opaque-envelope assembly meet applicable R-value or U-factor requirements. Windows and skylights must separately meet solar heat gain coefficient (SHGC) limits.
Continuous Insulation and Whole-Assembly Performance
U-factor measures heat transfer through the complete assembly, including the insulation, framing, and sheathing. Continuous insulation reduces thermal bridging across structural members, but attachments, penetrations, openings, and transitions can still disrupt that layer.
Project teams evaluating commercial building insulation requirements must account for those interruptions. Where continuous insulation is interrupted, the effective U-factor must be calculated using the applicable method in the adopted edition rather than treating the insulation layer as fully continuous. SHGC primarily applies to solar heat gain through fenestration.
HVAC Systems
The standard sets detailed efficiency requirements for HVAC systems. Pairing efficient equipment with Rmax polyiso insulation can reduce heat transfer through the envelope and lower the heating and cooling loads the HVAC system must serve.
Lighting
The standard sets lighting-power and control requirements, including provisions for automatic and daylight-responsive controls where applicable. LED lighting is one technology designers may use to help meet those requirements. Proper insulation also helps maintain stable indoor temperatures as lighting and mechanical systems contribute to overall building performance.
Contractors must also account for the edition adopted for the project and the changes introduced in newer editions.
Recent ASHRAE 90.1 Updates Every Contractor Should Know
Adherence to ANSI/ASHRAE/IES 90.1 is about more than following a set of guidelines—it directly influences a building’s energy consumption and operational costs. The standard governs key areas like insulation, HVAC systems, lighting, and service water heating.
By ensuring compliance, contractors reduce energy consumption and operational costs, while also enhancing environmental sustainability. This is particularly critical in regions with extreme temperature fluctuations, where inefficient insulation can lead to higher energy use and costs.
Building Systems Governed by ASHRAE 90.1
Building Envelope
A well-insulated building envelope is central to minimizing thermal transfer. Rmax polyiso insulation, with its superior R-values per inch, helps contractors meet ASHRAE's U-factor and solar heat gain coefficient (SHGC) limits, to ensure compliance with stringent energy standards.
HVAC Systems
The standard sets detailed efficiency requirements for HVAC systems. Pairing HVAC systems with Rmax’s polyiso insulation reduces thermal loss and improves overall system efficiency, to minimize energy demand.
Lighting
The standard also requires energy-efficient lighting systems, such as daylight-responsive controls and LED lighting. Proper insulation maintains stable indoor temperatures that complement these systems and further enhance building performance.
While these requirements form the foundation of ASHRAE 90.1, contractors must also stay informed about recent updates and how they affect building design and energy performance.
Recent ASHRAE 90.1 Updates Every Contractor Should Know
New editions are generally published every three years, with approved addenda developed between editions through continuous maintenance. The 2019 and 2022 editions introduced updates affecting HVAC systems, building envelopes, lighting, and energy-recovery requirements.
Increased HVAC Efficiency Requirements
The 2022 edition introduced COPHR for equipment that performs heat recovery during chiller operation and revised minimum efficiency requirements for several equipment categories. A high-performing envelope complements these provisions by reducing the loads placed on HVAC equipment.
Enhanced Building Envelope Requirements
The 2019 and 2022 editions increased envelope stringency. The 2025 edition raises the envelope requirements again with updated insulation requirements for opaque walls, roofs, and floors, along with increased stringency for windows and skylights.
Energy Recovery Systems
The standard includes energy-recovery requirements for qualifying systems that meet applicable airflow, outdoor-air, climate-zone, and operating-condition thresholds. These provisions do not apply identically to every HVAC configuration.
What Changed in Standard 90.1-2025?
Standard 90.1-2025 is the first full edition issued since 2022. It increases envelope stringency and adds proper-installation requirements for rigid insulation boards.
The edition also updates effective U-factor methods for steel-framed walls and assemblies where continuous insulation is interrupted. Contractors should follow the project details, the required calculation method, and current manufacturer instructions so the installed assembly performs as designed.
Confirm Which Edition Applies to the Project
The 2025 edition is the latest published version, but states and local jurisdictions adopt energy codes on different schedules. Some still use the 2019 or 2022 edition. Project teams should confirm the adopted code, local amendments, and permit requirements before finalizing the design.
Once a jurisdiction adopts or references an edition, the ASHRAE 90.1 energy code requirements govern covered projects in that jurisdiction. Standard 90.1 is an ANSI-approved consensus standard, while the IECC is a model energy code. A jurisdiction may adopt either framework or permit Standard 90.1 as the commercial compliance option.
Prescriptive and Performance Compliance Paths
ASHRAE 90.1 allows projects to demonstrate compliance through prescriptive requirements or approved performance-based methods.
Prescriptive Path
Under the prescriptive path, each regulated component and system must satisfy the requirements assigned to the project’s climate zone and construction type. Mandatory provisions still apply regardless of the selected path.
Performance Methods
Section 12 provides the Energy Cost Budget Method, which compares the proposed design with a budget building. Appendix G provides the Performance Rating Method, which compares the proposed design with a standardized baseline building and applies the performance target required by the applicable edition.
Both methods allow tradeoffs among systems when the complete design meets the required result. They also require detailed energy modeling, documentation, and compliance with applicable mandatory provisions.
How Rmax Polyiso Insulation Supports ASHRAE 90.1 Compliance
For ASHRAE 90.1 projects, Rmax polyiso can be used in envelope assemblies evaluated under either compliance path.
Advantages of Rmax Polyiso Insulation
Polyiso limits heat flow through the envelope by adding thermal resistance.
High R-Value per Inch
Polyiso insulation provides high thermal resistance per inch. Compared with lower-R-value insulation materials, it may reduce the thickness needed to reach the specified insulation level.
Air and Moisture Control Capabilities
Some polyiso products and evaluated assemblies can contribute to air and water control when installed with the required joint, penetration, and transition detailing. The approved assembly must identify the required air barrier, water-resistive barrier, and vapor-control layers.
Sustainability and Environmental Impact
Continuous polyiso insulation can reduce heat flow through the building envelope and lower heating and cooling demand. Project-wide environmental results depend on factors beyond the insulation layer.
How Rmax Products Support ASHRAE 90.1 Compliance
Rmax polyiso products can form part of an envelope evaluated through prescriptive requirements or whole-building energy modeling. Product selection alone does not establish compliance with the complete energy standard. Rmax polyiso products address opaque-envelope thermal performance; windows and skylights must separately satisfy SHGC requirements.
Thermasheath®
Thermasheath® provides continuous insulation for exterior walls and other applications listed by Rmax. Its thermal resistance helps the opaque assembly reach the specified R-value or U-factor.
Thermasheath®-SI
When installed as part of the evaluated system with the required joint and penetration detailing, Thermasheath®-SI can provide structural sheathing, continuous insulation, and air- and water-control functions. The evaluated system can address specified U-factor and air-leakage requirements.
Rmax Durasheath®
Rmax Durasheath® provides thermal performance and durable facers for listed wall, attic, crawl-space, vaulted-ceiling, and limited-roofing applications. Its thermal resistance can help the opaque assembly reach its required U-factor.
For projects governed by the 2025 edition, the selected product and its installation must match the approved envelope assembly.
Best Practices for Contractors to Support ASHRAE 90.1 Compliance
To support energy efficiency and compliance, contractors should follow the approved design, product instructions, and project-specific documentation requirements.
Continuous Insulation
Maintain continuous insulation across the building envelope, particularly around windows, doors, penetrations, attachments, and transitions, to limit thermal bridging.
Air Sealing and Moisture Control
Install the air barrier, water-resistive barrier, and vapor-control layer required by the approved assembly and climate. Seal joints, penetrations, and transitions according to the product instructions.
Comprehensive Compliance Documentation
Keep product data, approved details, installation and inspection records, and energy-model documentation when a performance path is used.
These strategies support compliance and can improve energy performance and indoor comfort when the complete assembly is designed and installed correctly.
Optimize Energy Efficiency With Rmax Insulation
Rmax polyiso insulation can support envelope assemblies designed to meet project-specific energy requirements. With high thermal performance and sustainability benefits, Rmax products can contribute to energy-efficient building designs. Contact us today for more information.
Frequently Asked Questions
The following questions cover scope, editions, adoption, and compliance paths.
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Standard 90.1 is an ANSI-approved standard that sets minimum energy-efficiency requirements for most sites and buildings other than low-rise residential buildings.
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The standard generally applies to commercial and high-rise residential buildings, new portions of buildings, and specified new systems and equipment in existing buildings.
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Standard 90.1 is a consensus energy standard. The IECC is a model energy code with commercial and low-rise residential provisions. Jurisdictions may adopt either framework or permit Standard 90.1 as a commercial compliance option.
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Projects may follow applicable prescriptive requirements or use a performance method. Section 12 provides the Energy Cost Budget Method, while Appendix G provides the Performance Rating Method.
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Standard 90.1-2025 is the latest published edition. The legally applicable edition depends on the state or local code adopted for the project.
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A new edition is generally published every three years. Approved addenda are developed between editions through continuous maintenance.
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Check the state and local commercial energy code, including amendments and effective dates. The authority having jurisdiction can confirm the edition required for permitting.