A good HERS rater goes well beyond code compliance verification: they are an important part of the project team to aid in your success and the betterment of the building. Bring the HERS rater on early to make the most of their expertise.
The MA 2015 IECC is very similar to the current 2012 IECC. Blower door and duct leakage testing thresholds remain the same, prescriptive R-values are the same, continuous ventilation and high efficacy lighting are still required. If you have successfully built to the 2012 IECC, you are in good shape.
The new Stretch Code is a bigger jump that requires a robust HERS 55.
The increase of HERS Ratings in Massachusetts in 2015, with an average index of 56, demonstrates that achieving that level of performance is not exceedingly taxing to the industry. The market can bear this level of efficiency and energy codes don't pain builders much.
The ERI path is an alternative to the 'prescriptive' aspects of the code (see 402.1 table below) . This provides more flexibility for meeting code, not to mention Mass Save New Construction rebate opportunities (IMO, a no brainer for every new residential build).
With appropriate design and a skilled builder, a building with an efficient envelope can be heated and cooled with point-source ductless minisplits. This is becoming increasingly popular in the high performance new construction sector.
I have been thinking a lot about the term ‘high performance’ to describe buildings. I like the term because it is broad, meaningful, and has yet to be co-opted by window sales people. High performance implies that the building functions- that the parts work together.
The Northampton Arts Trust building project is a retrofit of a steel framed building originally built in the 1980s as a drive-through lumber yard. When complete, it will be a lively downtown space for the performance and visual arts. A primary goal of the project is a building with very low energy costs; after a large capital investment, the non-profit requires low operational expenses. Energy modeling is being completed to inform thermal enclosure design and to leverage utility rebates and incentives.
The images below are from a basic infrared scan completed on Feb. 13, 2014. The insulation approach for the walls, roof, foundation walls, and slab are still being determined. The eQuest model will be completed soon to help assess the performance improvements of several enclosure system options.
- Steel frame with 2x8 stud walls to the interior. Metal cladding is fastened directly to frame, there is no sheathing. 'Bag 'n Sag' vinyl encased fiberglass was the original insulation strategy. Visual inspection shows this to be in decent condition with few rips. Estimate R-value (not accounting for wind-wash loses) R-2 - R-5
- Very poor fiberglass batts were installed in the 2x8 stud cavities. IR images mostly convey the performance of this material. R-2 - R-5 estimate thermal resistance value.
- There are significant connections through rim band areas to the basement. There are also major outside connections through exterior wall cladding above the drop-ceiling, the current very poorly defined 'boundary'. Significant air leakage is compromising existing batt insulation.
- Steel frame with 'bag and sag' was the original insulation strategy. A drop ceiling was installed, about 4' below roof deck, with 6" fiberglass batts and mechanical equipment and distribution system in the cold attic space.
- Roof structure is an original metal (or fiberglass?) roof with a standing seam metal roof later installed. It is assumed there is sheathing and the appropriate membrane materials under the standing seam roof.
Remove existing metal panel cladding 4-6" of polyisocyanurate to exterior of existing wall. R-26- R-39
Optional: With frame of building exposed, remove existing fg batt, and 'bag and sag' insulation from exterior and insulate 2x8 framed cavities with mineral wool batts . R-24
Remove drop ceiling and remove existing standing seam roof and install 6"- 8" of polyisocyanurate on exterior of existing roof. Install sheathing, continuous WRB, air control membrane, and new standing seam roof. R-39 - R-52
Optional - remove 'bag and sag' and install 3-4" of closed cell rigid foam to the interior of roof deck.
Builders and designers that specialize in energy efficient buildings will not have a problem with the shift to the 2012 IECC. Yet other builders may have some serious wake-up calls. Fortunately there are some proven strategies that will all but ensure compliance with the 2012 IECC and pending Stretch codes.
In the spirit of ‘year in review’ countdowns, here are my....
8 strategies to surpass the 2012 IECC residential energy code
The 2009 IECC has been referred to as the training wheels for the 2012 IECC, which is weeks away from being adopted in Massachusetts with an expected 12 month contingency period. The Stretch Code will then be revamped to exceed the 2012 IECC levels. This suite of 'advanced energy codes' will create buildings that are ready for what I like to call the 'low energy future.'
Impacting several buildings a year is great, but using technology to scale residential energy retrofits is what is drastically needed to solve our building energy crisis.
Since utilities and implementation contractors aren’t exactly on the cutting-edge of innovation to streamline residential energy efficiency projects, why haven’t tech and building savvy start-ups jumped at the glaring opportunity to drive residential EE with data?
The utility provided assessments and amazing rebates and financing offerings serve many homeowners well. Yet for homeowners wanting to significantly change their homes- address ice damming, solve comfort issues, or achieve 25-50% energy savings- these services are not appropriate. A more detailed assessment approach is needed to identify improvements and communicate to the customer the value of investing in comprehensive solutions.
After the first round, the field has been narrowed to two. The second round of the election begins on Monday March 4. Please vote again. The EEAC is adding a seat representing Small Business energy efficiency interests. Thank you for your support of Adin Maynard.