Code and Performance Path

December 12, 2017

We're almost one year into the new Ontario Building Code Supplementary Standard SB-12 Energy Efficiency requirements and this article by Gord Cooke which was originally published in Better Builder Article, October 2016is a great summary of the trends emerging from the changes.

In my article for the last issue I mentioned that the draft of the Ontario Building Code Supplementary Standard SB-12 Energy Efficiency requirements for January 2017 had come out. Well in the ensuing weeks, the final version of SB-12 for 2017 has been made public and there are some compelling trends to discuss. First, the number of prescriptive packages is down reflecting the fact that it is getting tougher to find significant, cost effective incremental energy improvements through simple changes to insulation levels or mechanical equipment specifications. Second, there is a not so subtle mention of air tightness, with the supporting documents of SB-12 hinting that in future code iterations air tightness testing will be mandatory.

In this iteration there is at least a series of helpful trade-offs for builders who do a good job of air leakage control. These first two trends support what I consider to be the most important change to SB-12; the clarifications and emphasis on the "Performance Path" and "Other Acceptable Compliance Methods" sections of SB-12. In the same way that the International Energy Conservation Code 2015 in the US and the National Building Code of Canada 2010 (Section 9.36) have moved to a more objective, performance path based on energy modeling, the new SB-12 demonstrates a compelling opportunity for builders to work with their Energy Advisor to find the most cost effective in meeting the new code requirements. In this new SB-12 not only is there a stronger reference to ENERGY STAR for New Homes and R-2000 as being Alternative Methods, there is a more clearly defined Performance Path that gives builders flexibility to show compliance using anyone of 6 different energy simulation software programs against a "reference" home. It is my opinion that any builder who is truly looking for the most cost effective way to build a home that adheres to basic building science principles for a safe, healthy, durable, comfortable and efficient home will use the Performance Path.

The following table may help demonstrate why I think the Performance Path will be the most cost effective approach. Lets compare incremental costs versus incremental energy savings of changes needed within the Prescriptive Path to get from the most commonly used Package J in the 2012 version to what many project to be the most popular package in the 2017 version, Package A1.

Notice in the table, that the least effective upgrade is the attic insulation at over $500 per GJ saved. We are clearly seeing the diminishing returns of adding insulation to ceilings. Note too that controlling air leakage rates to current ENERGY STAR levels is more cost effective than adding attic insulation and increasing basement insulation combined. I think air tightness is a critical aspect. Section 9.25.3 Air Barriers of the code identifies 16 separate air sealing measures with words such as "shall be sealed …, continuous barrier to air leakage …. and maintain integrity of the air barrier over the entire surface". These words, in my opinion are both a risk and an opportunity. If you do them well, you will achieve air tightness levels well below the 3.0 ACH50 hinted at in code at very low cost. If you don't do them well and you don't test for air tightness, you are at risk from any homeowner who feels even the slightest draft around an electrical outlet or under a baseboard. In other words, smart builders across North America are doing air tightness testing anyway as both a quality assurance measure and a risk mitigation measure. Now, under the new SB-12 you can get very cost effective energy credits for doing it if you use the Performance Path.

Air leakage control is just one aspect of making sound decisions in light of the code change. Using the Performance Path would encourage you to better evaluate windows to optimize both summer and winter comfort performance while at the same time being able to "right-size" your furnace and air conditioner sizing to optimize costs. The Performance Path can also help you find better ways to insulate basements to avoid moisture issues. It is my sincere opinion that the new code tips the scales in favour of using an integrated design and performance testing approach to ensure healthier, safer, more comfortable, more efficient and more durable homes all in a more cost effective way.

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