IECC 2018 and ASHRAE 90.1-2016

The next code cycle is the IECC 2018 code and the ASHRAE 90.1-2016 Standard. ASHRAE 90.1-2016 has been published and the IECC 2018 has just recently been made available. You will see the majority of changes in air sealing and blower door testing*. Additionally, there’s a reduced BTU table for semi-heated space. This means that the maximum allowable heat output per climate zone has been reduced, thus making the semi-heated compliance path more difficult to use.

* Comparison is based off IECC 2015 and ASHRAE 90.1-2013.

IECC 2015 and ASHRAE 90.1-2013 the Most Widely Adopted “New” Code

While the ASHRAE 90.1-2016 Standard has been published, states are yet to adopt it. The most widely adopted “new” code cycle is IECC 2015 and ASHRAE 90.1-2013. Here are the highlights from my blog post in October, which covered the IECC 2015 and ASHRAE 90.1-2013 updates in detail:

• Higher insulation values: IECC 2015 and ASHRAE 90.1-2013 have the most stringent envelope requirements based on “Conditioned Space” and “ Non-Residential Space”. This means that, for the most part, contractors will need to use Banded Liner Systems (Ls) or Long Tab Banded Systems (Fc) in order to meet the stricter insulation requirements.
• Air barrier requirement: Both IECC 2015 and ASHRAE 90.1-2013 require an air barrier in the thermal envelope, and for it to be indicated in drawings. It can be placed on the interior side, exterior side, somewhere within assemblies composing the envelope, or any combination thereof.
• States that have adopted IECC 2015/ASHRAE 90.1-2013 include: Alabama, California, Illinois, Maryland, Massachusetts, Michigan, New Jersey (adopted ASHRAE 90.1-2013), New York, Oregon, Utah, Texas, Vermont (state-specific code modeled after IECC 2015) and Washington. Georgia is also slated to adopt the code cycle over the next few months.

The Biggest Question to Answer for 2018: “What Do I Need to Meet Code?”

As we move toward more complexity in each code cycle, this longstanding question will only become even more prolific. As simple as the question is, it is very difficult to answer. In short, the compliance path I recommend most often is the prescriptive approach. Per the U.S. Department of Energy, the prescriptive approach includes “requirements that either must be met by every building design, or if the requirement is not met, a tradeoff must be made to “make up” for not meeting that requirement.” In other words, you must meet all U-values of the roof, walls, foundation and fenestrations. If a tradeoff is indeed needed in the end, the quoted price has covered any changes.