Making sense of the Massachusetts Stretch Code
Constantly evolving code changes are some of the toughest things to navigate as a contractor – especially after working 70 hours, sending countless emails, taking 60 phone calls and texts, all to accomplish the thing you were hired to do - build a house. My wife Liz and I ran a contracting business for 15 years before I shifted my focus to residential energy. Today, I love what I do, but it’s no secret that the Energy portion of the Massachusetts Code is a juggernaut that has evolved over the past 25 years into one of the most progressive and complex Energy Efficiency Codes in the country. And while the intent of the code is to work towards mitigating climate change with measurable success, the Massachusetts Energy code is a double-edged sword for builders.
The difference in this code cycle as opposed to cycles past is the elimination of the "concurrency period" which allowed towns to implement the code six months or a year after the code was published, effectively giving towns time to train staff, and then adopt the code. One of the challenges was that neighboring towns would choose different dates, adding a layer of complexity for builders working in multiple towns.
This year the Department of Energy Resources and the BBRS have consolidated their effort into a single code rollout. The intent was to eliminate confusion, creating continuity across town lines. We've been working to make sense of it all in coordination with the Nantucket Building Department.
The good news: in this cycle, the changes should be easy to implement. We're still using the HERS Index for all new construction, as has been the case since the Town of Nantucket voted to pursue Green Communities designation—and subsequently the Stretch Code—back in 2019. Three hundred towns have adopted the stretch code as of November 14, 2022.
Here are the key points of the current Stretch Code as of January 1, 2023:
HERS 55 allowed if the home is all-electric
HERS 52 required if any oil, propane or natural gas is used in the building
Of note: The average HERS Rating in MA in 2020 was HERS 51
HERS 55 (Fuel + Solar) or HERS 58 (Electric + Solar) is also allowed if there is a solar Photovoltaic system installed
1 EV-Ready parking space and wiring per home is required for 1 and 2 family dwellings and townhomes and the number of EV-Ready parking spaces for new multi-family parking areas increases from 10% to 20% of parking spaces.
An ERV or HRV is now required. There are some models we recommend using (with lower wattage) that help the HERS rating, but you can use any brand you would like. You will still need to meet the required CFM of ventilation under ASHRAE 62.2. Important to note: bath fans can no longer be used to meet the requirement for whole-house mechanical ventilation.
HVAC duct leakage testing is now required for ALL systems, even if all ducts are within the conditioned envelope. This is to verify the systems installed were appropriately sealed. Ducts in the thermal envelope do still have distribution loss, contrary to a common misconception. Poorly sealed ducts could lead to indoor air quality problems, system balancing issues, and reduced efficiency.
Here is a list of code amendments (Thanks to Chis Mazzola for this compilation and the above list of changes):
R403.6 Add heat or energy recovery ventilation for HERS pathway (from IECC 2024 REPI-93)
R404.4 Modify EV ready wiring from 10% to 20% of multi-family spaces, with exceptions
R406 HERS rating option phased-in update from HERS 52/55 to HERS 42 fossil / HERS 45 electric
R406 and R502 HERS 65/70 to HERS 52/55 for major home alterations /additions over 1,000sf and change of use
R502 and R503 Adds clarifying language on when additions and alterations comply with HERS Rating for base code or with prescriptiv e code
The preconstruction process is a collaborative effort requiring good up-front planning. We’re here to help navigate the waters. Our focus is on integrative design, making the impactful up front choices in order to minimize expensive changes at the end of a project. The goals are achievable, but it requires good planning.
There is lots to discuss: emerging technology is constantly changing around heat pumps and ERVs and the market is responding; continuous insulation on wall and roof assemblies are becoming the norm; and we’re debunking myths and acknowledging the advantages around old technologies.
The bottom line: With a good insulation spec; good window performances; a solid HVAC plan including a Manual J; a ventilation plan including an ERV or HRV; and a focus on air sealing, builders are achieving the strict targets of the Stretch Code already.
Anticipating next year’s even lower HERS scores, we’re looking forward to continuing to help Nantucket builders create homes we can all be proud of for generations to come.