Building Energy Efficient Homes in Massachusetts
Massachusetts has some of the most demanding energy codes in the country — and some of the best incentives for exceeding them. As certified HERS Raters who have worked on hundreds of new construction projects across the state, we have seen what works. Here are our top tips for building an energy-efficient home in Massachusetts that meets or exceeds the MA Stretch Code 2021.
1. Engage Your HERS Rater at the Design Phase
The single biggest mistake builders make is waiting until the end of construction to call a HERS Rater. Engage your HERS Rater before permit submission. Early energy modeling can identify opportunities to improve your HERS score at minimal cost — and prevent expensive redesigns later. Under the MA Stretch Code, your HERS Rater needs to review your plans before construction begins anyway.
2. Prioritize the Building Envelope
The building envelope — walls, roof, foundation, windows, and air barrier — is the most cost-effective place to invest in energy efficiency. For Massachusetts new construction, target: R-38 to R-60 attic insulation; R-20+ continuous wall insulation (exterior rigid foam or mineral wool); R-15+ basement walls; triple-pane windows (U-0.20 or lower); and airtight construction targeting 1.5–2.0 ACH50.
3. Choose the Right HVAC System
Cold-climate heat pumps have transformed Massachusetts energy efficiency. A properly sized cold-climate heat pump (ASHP) with a COP of 3.0+ at 17°F dramatically lowers your HERS score compared to gas heating. Pair it with a heat pump water heater for additional energy savings and Mass Save rebates. Avoid oversizing — it hurts both efficiency and comfort.
4. Air Seal Aggressively
Air leakage is one of the biggest sources of energy waste in new construction. The MA Stretch Code requires 3.0 ACH50 or less — but the best builders target 1.5 ACH50. Key air sealing locations: top plates and bottom plates; all penetrations (electrical, plumbing, HVAC); rim joists; attic hatches; recessed lights (use airtight IC-rated fixtures); and window and door rough openings.
5. Install Tight Ducts (or Go Ductless)
Duct leakage wastes energy and hurts comfort. The MA Stretch Code requires 4 CFM25/100 sq ft or less. The best approach: use short duct runs, all within conditioned space; apply mastic sealant at every joint; seal supply and return boots to drywall; and test before drywall if possible. Even better — go ductless with mini-split heat pumps and eliminate the duct leakage issue entirely.
Get Your Massachusetts New Construction HERS Rating
HERS Rating Company works with Massachusetts builders who care about building quality, energy-efficient homes. We provide plan review, energy modeling, and all required testing and certification. Contact us to discuss your next project.
Related Services in Massachusetts
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Top Energy Efficiency Tips for New Construction in Massachusetts
Building efficiently in Massachusetts means meeting MA Stretch Code 2021 standards. Top strategies: air seal to under 2.0 ACH50 (code requires 3.0), use heat pump HVAC systems, exceed minimum insulation levels, and work with HERS Rating Company during design for early plan reviews that catch compliance issues before construction begins.
Work With HERS Rating Company From Day One
Our pre-construction plan reviews identify energy efficiency opportunities early — when changes cost much less than construction-phase corrections. We serve all 351 Massachusetts cities. Call 617-584-1809 for a free new construction consultation.