HERS Score Calculator (BETA)

Does not meet Stretch Code

Common 2×6 wall upgrade; may meet Stretch Code via HERS performance path. Prescriptive code requires R-20+5ci.

Exceeds code; significant thermal improvement

Below Stretch Code minimum

Current MA Stretch Code requirement

Previous Stretch Code target; excellent for cold climate

2006 IECC baseline. Current MA code requires R-10 at 4 ft depth. Standard poured concrete with perimeter foam.

Extended perimeter insulation — moderate improvement

Insulated Concrete Forms — continuous insulation with zero thermal bridging. Our standard ADU foundation method.

Meets code; standard double-pane low-E

~30% better than U-0.30; good value

Premium; best for passive house level

Standard fiberglass or steel insulated door

Better weatherstripping and thermal break; triple-pane glass if glazed

European-style thermal break doors; maximum insulation value

Blocks most solar heat — good for cooling, less helpful for heating

Captures passive solar heat in winter — beneficial in MA's heating-dominant climate. Best on south-facing glazing.

Minimal air sealing effort

Typical for careful construction

Required for MA Stretch Code prescriptive compliance (2021 IECC §R402.4.1.2)

Exceptional; requires meticulous detailing. Passive House standard is 0.6 ACH50.

Mixed-fuel baseline; requires ductwork

All-electric option; moderate efficiency

Best for ADUs — no ductwork, high efficiency, lowest cost. Mass Save: $250/ton up to $2,500 for new construction (up to $8,500 if replacing existing heating). Must be ENERGY STAR Cold Climate certified.

Premium; cold-climate certified for MA winters. Mass Save: $250/ton up to $2,500 for new construction (up to $8,500 if replacing existing heating). Must be ENERGY STAR Cold Climate certified with R-454B refrigerant.

Does NOT meet MA code as of Feb 2025 — HRV/ERV required for new ADUs. Shown for reference only.

Recovers 60-90% of heat; meets 2025 requirement

Recovers heat + humidity; best for tight buildings

No scheduling capability

Setback scheduling reduces heating/cooling during unoccupied hours. HERS credits programmable; no additional credit for 'smart' features.

Duct leakage can account for 25% of energy loss

Verified by duct blaster test

Eliminates duct losses entirely; ideal for ADUs

Cheapest upfront; least efficient

Better efficiency; on-demand heating

3-4x more efficient than gas. Mass Save: $750 rebate ($1,500 for split systems). Needs ~700 cu ft of space and produces cool air.

No solar offset

Partial offset; does NOT trigger MA 3-point target relaxation. MA state credit: 15% up to $1,000.

Relaxes MA HERS target by 3 points (e.g. 52→55); good for 600-900 sq ft ADU. MA state credit: 15% up to $1,000.

Approaches net-zero for ADU; maximum offset. MA state credit: 15% up to $1,000. SMART program incentive may also apply.

HERS target: 52 (Stretch/Specialized). Requires gas service connection.

HERS target relaxes to 55 (3 points easier). Eliminates gas line costs (~$2,000-5,000 savings). Score benefit comes from efficient equipment choices above.

Typical new construction

Small improvement; easy win

Default HERS assumptions

Lower energy consumption across all appliances