March 5, 2020
by Star Building Systems
2019 saw significant movement throughout the commercial energy code landscape. In addition to a large number of states adopting newer code cycles, we saw more interest than ever in the building envelope code requirements affecting projects throughout the country. With plenty of new changes on the horizon, let’s dive into the top building envelope code updates you need to know for the rest of the year.
The majority of states have adopted IECC 2012/ASHRAE 90.1-2010 or beyond.
As of January 1, 2020, the following states have adopted new codes:
Later this year, several states will adopt new codes or make updated requirements, such as:
This list is not exhaustive and plenty more updates are on the horizon. It’s important to remember to check with your local jurisdiction, as county-level adoptions often overrule the effective statewide code cycle.
Though ASHRAE 90.1-2019 has been published and is available on the ASHRAE website, the more common “recent” code cycle is IECC 2018/ASHRAE 90.1-2016; thus, the majority of this post will focus on IECC 2018/ASHRAE 90.1-2016. Depending on which code cycle your state/county has adopted, you may or may not see much of a jump in envelope efficiency requirements. Here are the highlights of the most recent code cycle, IECC 2018/ASHRAE 90.1-2016:
IECC 2018/ASHRAE 90.1-2016 saw about a 2% increase in energy efficiency in commercial buildings from the prior code cycle, IECC 2015/ASHRAE 90.1-2013. It’s important to remember that total energy savings depends on the compliance path used; the prescriptive path, the performance path, and the trade-off method all yield a different outcome on overall energy savings. The performance path has become more popular for stretch codes and above code programs. This gets very difficult to demonstrate for the average design build contractor.
The first mention of air barriers was in IECC 2009, and the IECC 2015/ASHRAE 90.1-13 made air barriers mandatory provisions. I continue to highlight this requirement in any code update, as many folks are surprised when air barriers are noted as mandatory. The air barrier must be located within the building’s thermal envelope. It can be placed on the interior side, exterior side, somewhere within assemblies composing the envelope, or any combination thereof. It is also mandatory to identify the air barrier in drawings and for it be continuous across joints and assemblies. Joints and seams must be sealed and securely installed. Penetrations and joints and seals associated with penetrations must be sealed in a manner compatible with construction material and location.
3% of the roof area is still mandatory under IECC 2018/ASHRAE 90.1-2016. There are exemptions, but limited for buildings over 2,500 SF.
Weather Resistive Barriers have become a focal topic throughout Oregon and Washington, with other states to inevitably follow. The ICC Structural Specialty Code (Chapter 14) highlights the weather resistive barrier requirement. Section 1402.2 “Weather Protection” notes:
“Exterior walls shall provide the building with a weather-resistant exterior wall envelope. The exterior wall envelope shall include flashing, as described in Section 104.4. The exterior wall envelope shall be designed and constructed in such a manner as to prevent the accumulation of water within the wall assembly by providing a water-resistive barrier behind the exterior veneer, as described in Section 1403.2, and a means for draining water that enters the assembly to the exterior. Protection against condensation in the exterior wall assembly shall be provided in accordance with Section 1404.3.
This section of the code pertains to walls, and building permits will not be issued without showing compliance. For metal buildings, testing or compliance with Section 1403.2 and 1404.3 is mandatory; compliance is not assumed, and therefore an option for testing per ASTM E331 must be demonstrated. All metal building wall panels (i.e. single skin and insulated metal panels) should be tested per ASTM E331. If this is done, you are exempt per section 2 above. There are also other exemptions, but metal buildings are not exempt and therefore need to address this section and their products. I have seen some testing per the above for some panels by a few manufacturers, but most are insulated metal panels.
In looking ahead at future cycles, no major changes are expected in the actual thermal envelope for commercial buildings. The mandatory provisions are the future cycle and will require actual blower door testing for air tightness. ASHRAE 901.-2019, which is published, contains this requirement. There are exemptions, but very limited. The primary reason for these provisions is simple: Energy savings. When a new building is constructed with the thermal envelope requirements, it’s not actually efficient if the building is leaking air and no natural light to offset energy consumption with lighting and mechanicals.
There are also other options that have been receiving attention lately, and which go beyond the codes outlined here, such as stretch codes and envelope commissioning. Stretch codes are current in some states and each town, city or jurisdiction would typically require and enforce compliance over the actual state code. These codes are generally written about 10% more energy efficient than the state code. Future stretch codes increases are projected to be around 20%-40%. Envelope commissioning options have several protocols and certification requirements during construction and through the completed design process. Once achieved, these building are certified to operate at a fixed cost on energy savings. The final goal is Net Zero for all buildings. Currently, residential and commercial buildings account for 40% of energy use in the U.S. (ase.org). Based on the overall state adoption of the new codes, the projected energy and carbon emissions savings are extensive, and carry the potential for a major impact on the future U.S. building landscape.
In summary, commercial energy codes have evolved quite a bit from their initial adoption years ago, and the landscape has become increasingly complex. The most recent code cycles carry more stringent building envelope performance requirements, which, ultimately, propel new innovations and lead to more energy-efficient buildings.
About the Author
Bill Beals, District Manager of Therm-All (www.therm-all.com), is a 32-year veteran of the metal building industry and a contributing member of several committees, including the Metal Building Manufacturers Association (MBMA) Energy Committee and NIA’s Metal Building Insulation Laminators Committee (chairperson). Mr. Beals also belongs to the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) and International Code Council (ICC), and is often invited to share his extensive energy code knowledge through presentations at industry conferences. Mr. Beals has contributed to many articles and reference guides, and authors bi-monthly commercial energy codes blog called “The Code Man.” He can be reached at firstname.lastname@example.org.
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