2015 IECC and the 2017 Massachusetts Stretch Code

The 2015 IECC and the updated Stretch Code is effective for all projects permitted after Jan 1, 2017

See the follow up post here:  Tips to pass the 2015 IECC

Energy waste from poorly insulated and air sealed knee-walls is one of the symptoms of past energy blind building codes. 

Energy waste from poorly insulated and air sealed knee-walls is one of the symptoms of past energy blind building codes. 

Looking at snow melt patterns after the season's first few snow falls, we are painfully reminded that the Northeast building stock is responsible for gross energy loss. After a week staying in Airbnb's I am also reminded that indoor air quality and comfort are compromised by poor energy performance - overly dry air is worse than an overly soft mattress.

With so many challenges in our society, can't we at least make our buildings comfortable and efficient? Recent energy code changes (as long as they are enforced) will ensure that newly constructed buildings will be a lot better than buildings designed and constructed to past energy codes.  

63% of Massachusetts municipalities have adopted the Stretch Code. Here is the latest list of Stretch Code communities with dates of adoption  [PDF download].

Here is Chapter 11 (energy efficiency section) Massachusetts Amendments to the 2015 IECC, including Stretch Code language . It's only 7 pages. [PDF download]


What you need to know about the 2015 IECC code

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 biggest differences between the 2012 IECC and the 2015 IECC:

  •  ERI (HERS rating) path option: You can sidestep the prescriptive code requirements if you achieve a HERS score of </= 55 .  The mandatory code requirements are still relevant. This was included in the MA Amendments to the 2012 IECC, but now it is included in the base code so it should be more widely accepted. For projects that will seek to leverage Mass Save New Construction rebates, a HERS rating will be completed anyway, so this path is practical.
  • Windows must be better, below U-.30 from U- .32.  Many windows fall in the U.27-U.30 range, so this should not dramatically increase window costs. If specialize windows are specified, such as glass bricks, the ERI (HERS Rating) path may be required to sidestep the window U-value requirement. 

The 2015 IECC prescriptive R-value requirements. Zone 5 includes most of Massachusetts. These values do not need to be followed if following the ERI (HERS rating) path to compliance. The U.30 window requirement is specific in the MA Amendments.

The 2015 IECC Stretch Code gets simplified, more stringent, and better aligned with the base code.

The Stretch Code has been behind the base code. Up until today it had referenced the 2009 IECC. As of Jan 1, 2017 it is aligned with the base 2015 IECC code, with a big drop in the HERS index requirement. 

All new construction projects in Stretch Code communities (here's that map again) must achieve a HERS score of 55. For some context, the average HERS rating in Massachusetts in 2015 was 55. There are two other paths to compliance:  1. Energy Star V3.1 certification  2.  a PHIUS Certified consultant verifies, using the PHIUS+2015 software, that there is Specific Space Heat Demand of less than or equal to 10 kbtu/ft/year (home doesn't actually need to be Passive House Certified)

My #1 tip for new construction projects in Stretch Code communities, is to work with a HERS rater early in the design process. Building to this standard is more expensive if code failures require midstream repairs and retesting. As HERS raters, we are here to support builders through the process - HIS & HERS includes consulting in our standard HERS Rating service. 

HERS index tradeoffs for renewable energy systems

There are offsets for solar and renewable energy systems - up to 12 points. (HERS 67) . A higher (worse) HERS score is allowed if a PV system , renewable primary heating, or solar thermal hot water systems are installed at the time of construction. 

Renewable energy trade-offs are new to the 2015 IECC Stretch Code. Note that the HERS rating is calculated without renewable energy generation for code and local rebate programs. 

In summary

Stretch Code communities have a big jump to hit HERS 55, a significant improvement from the last Stretch Code. Base Code projects do not see many`changes.

As always, we are here for any questions you might have. We look forward to providing HERS rating services for your next project and working with you to ensure a smooth path to code compliance, and a building that is comfortable and energy efficient.