7 minute read
Decoding Energy Efficiency
By Parker Allen
Navigating ASHRAE 90.1 and IECC
The two primary commercial energy codes that underpin state energy regulations in the U.S. are ASHRAE 90.1 and the International Energy Conservation Code (IECC). Both are essential to creating energy-efficient buildings and reducing greenhouse gas emissions, yet they differ in their approach, adoption, and impact. These codes are updated regularly to reflect advances in technology and energy efficiency standards.
In a recent webinar by BetterBricks, a resource from the Northwest Energy Efficiency Alliance, expert Nick O’Neil of Energy 350, Inc. examined these codes in detail, highlighting the similarities and differences between ASHRAE 90.1 and IECC and their use, not only in the Pacific Northwest, but across the country. His insights form the basis of this article – for further research into the topic, the full webinar can be found here.
OVERVIEW OF ASHRAE 90.1 AND IECC
ASHRAE 90.1, published by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), is widely considered the most technically rigorous energy code, O’Neil pointed out. Updated every three years, the code covers all U.S. climate zones, with different requirements for each. ASHRAE 90.1 is intended for commercial and industrial facilities, with exceptions for certain residential occupancies in mixed-use buildings.2 At over 500 pages, it is dense and highly technical.
The code offers two paths for compliance. The prescriptive path involves meeting a detailed set of requirements that cover various systems, including HVAC, lighting, and water heating.
In contrast, the performance path allows designers more flexibility, especially when working on complex buildings that don’t fit within the prescriptive framework. By modeling energy performance and trading off efficiency measures, a designer can meet the energy code’s standards while making unique design choices, such as increasing the window-to-wall ratio and compensating with a more efficient HVAC system
The International Energy Conservation Code (IECC), published by the International Code Council (ICC), is a less technical but equally critical energy code. Unlike ASHRAE 90.1, the IECC has separate provisions for residential and commercial buildings. It, too, is updated on a three-year cycle, but its language is easier to understand and is designed to be more accessible to code officials and the general public, O’Neil pointed out. At about 250 pages, IECC is shorter and more user-friendly than ASHRAE 90.1.
One of IECC’s most significant features is its C406 credits, which allow designers to select from a variety of efficiency measures to meet the energy code’s requirements.3 This flexibility makes IECC an appealing option for many states. However, while IECC is simpler in structure, it is often seen as less stringent than ASHRAE 90.1, which is why some jurisdictions, particularly in the Pacific Northwest, have chosen ASHRAE as their base energy code.
ADOPTION AND CUSTOMIZATION
Across the country, states have adopted different versions of ASHRAE 90.1 and IECC, and they amend these codes to suit regional needs. O’Neil, focusing on the Pacific Northwest, discussed the variability among states in the region, which serves as an example of the variability nationwide.
Washington, he pointed out, is widely regarded as one of the most stringent states when it comes to energy codes. It bases its energy regulations on the 2021 IECC but adds numerous state-specific amendments. Oregon, on the other hand, uses ASHRAE 90.1 as the foundation of its energy code, with several amendments unique to the state. Both Idaho and Montana use the IECC as their base code, but with varying degrees of customization. Idaho references the 2018 IECC with amendments, while Montana adopted the 2021 version. Montana also amends its version of the IECC, adding provisions that cater to the unique needs of the state.
The takeaway is that, in addition to familiarizing yourself with the codes in general, specific knowledge of your state’s code adoption and additional provisions is paramount.
SIMILARITIES AND DIFFERENCES
Although ASHRAE 90.1 and IECC differ significantly in their technical complexity, they share many similarities. Both codes offer prescriptive and performance paths for compliance, and they require designers to meet energy-efficiency standards across multiple systems, including HVAC, lighting, and water heating. Both codes also rely heavily on modeling to establish compliance under the performance path, allowing designers to trade off one efficiency measure for another.
However, ASHRAE 90.1 is generally considered more stringent. Its technical subcommittees, which include experts in various fields such as HVAC and lighting, review and vet proposals before they are added to the code. This process ensures that the code is both comprehensive and technically sound. In contrast, the IECC allows for more public participation in its amendment process. Proposals can be submitted by anyone, making the code more open but potentially less rigorous.
As referenced earlier, one notable feature of IECC is its additional credits system (C406), which allows builders to choose from a list of energy-saving measures. These measures range from improving HVAC system efficiency to enhancing building envelope performance. Designers must accumulate a certain number of credits to comply with the code, adding an element of flexibility that is not as prevalent in ASHRAE 90.1.
THE FUTURE OF ENERGY CODES
The evolution of energy codes is a continual process, with new updates every three years. One of the major trends identified by O’Neil is the increasing focus on performance paths, which allow for greater flexibility in how designers meet energy efficiency goals. Additionally, there is a growing emphasis on energy credits, controls, and more integrated systems.
For example, total system performance ratio (TSPR), a newer feature in ASHRAE 90.1, evaluates the performance of an entire HVAC system rather than its individual components. This approach encourages more efficient system design, helping buildings optimize their energy performance as a whole. Similarly, the IECC is continuing to refine its credit system, focusing on carbon reductions and energy savings across different building types.
Both codes are expected to incorporate more advanced control requirements for lighting and HVAC systems. These controls help manage energy use more effectively by responding to occupancy, daylight, and other factors. In states like Washington, the next iteration of energy codes will likely include more stringent energy use intensity (EUI) targets, aligning code requirements with broader state energy and carbon reduction goals.
CONCLUSION
Building energy codes are crucial to reducing energy consumption, lowering greenhouse gas emissions, and creating more sustainable buildings. ASHRAE 90.1 and IECC are both essential tools in this effort, though their complexity and applicability vary across states. The future of energy codes will likely see continued improvements in building performance, more stringent control measures, and increased flexibility for designers. However, navigating these codes remains a challenge, especially as they become more detailed and integrated with emerging technologies.
For those working in the field of energy efficiency, keeping up with the latest developments in ASHRAE 90.1 and IECC is critical. With new updates on the horizon, these codes will continue to shape the energy landscape of commercial buildings for years to come.
REFERENCES
1 O’Neil, Nick. “Cracking the Codes: The Present and Future of Northwest Energy Codes.” betterbricks. Northwest Energy Efficiency Alliance. https:// betterbricks.com/resources/nwenergycode
2 “Commercial and Residential Building Energy Codes.” U.S. Department of Energy. https://www.energycodes.gov/commercial-and-residentialbuilding-energy-codes
3 “SECTIONC406: Additional Efficiency Requirements.” ICC Digital Codes. International Code Council. https://codes.iccsafe.org/s/IECC2021P2/ chapter-4-ce-commercial-energy-efficiency/IECC2021P2-CE-Ch04-SecC406
4 “State Portal.” U.S. Department of Energy. https://www.energycodes.gov/state-portal
5 “State Portal.” U.S. Department of Energy. https://www.energycodes.gov/state-portal
