Primary Sources
Sourcing rules
- Primary sources only. Government agency pages (Mass Save, MA DOER, IRS, EPA, DPU), official utility tariff filings, code documents, and standards bodies. We do not cite secondary blogs or aggregator content as factual references.
- Date everything. Every rebate dollar, eligibility rule, and program parameter on the site carries an "as of" date that matches a verification cycle below.
- Quarterly cycle for rates. Anything that can move quarterly — utility rate schedules, Mass Save rebate amounts, HPQPL listings — is re-verified once per quarter.
- Event-driven cycle for rules. Federal credit status, refrigerant transition, MLP list changes, and code revisions are re-checked when the underlying rule changes.
- Public corrections. If we get a number wrong, the correction is dated and logged in the Incentives Changelog rather than silently edited.
Mass Save program documents
- Mass Save Heat Pump Qualified Products List (HPQPL) ↗
Mass Save
The authoritative list of cold-climate heat pumps eligible for the Mass Save Whole-Home, Partial-Home, and Basic rebate tiers — including the R-410A removal effective Jan 1, 2026.
Re-verified quarterly
- Mass Save Residential Heat Pump Rebates (program page) ↗
Mass Save
Rebate amounts per ton ($2,650/$1,125/$250), per-home caps ($8,500/$8,500/$2,500), eligibility rules, and required documentation.
Re-verified quarterly
- Mass Save HEAT Loan ↗
Mass Save
HEAT Loan rate (0% APR), loan cap ($25,000), and SMI-tiered term lengths (84/60/36 months).
Re-verified quarterly
- Mass Save Inflation Reduction Act (HEAR) program page ↗
Mass Save
IRA-funded Home Electrification and Appliance Rebates (HEAR): up to $8,000 for heat pumps, $4,000 for electrical panel upgrades, income-tiered (≤80% AMI standard, ≤80% AMI Turnkey).
Re-verified quarterly
- Mass Save Sponsors / About Page ↗
Mass Save
The six sponsor utilities (Eversource, National Grid, Unitil, Cape Light Compact, Berkshire Gas, Liberty Utilities) and program structure.
Re-verified when the underlying rule changes
MA Department of Energy Resources / mass.gov
- MA Municipal Light Plant Zero-Interest Energy Efficiency Loan ↗
Commonwealth of Massachusetts
The statewide 0% APR up to $25,000 financing program for MLP customers (the MLP analog to the Mass Save HEAT Loan).
Re-verified annually
- MA Municipal Light Plant Communities (DOER) ↗
MA Department of Energy Resources
The official 41-town MLP list — used for our utility-mapping table and to determine which homes are excluded from Mass Save.
Re-verified when the underlying rule changes
Federal (IRS, Congress)
- IRS Energy Efficient Home Improvement Credit (§25C) ↗
Internal Revenue Service
Confirms that §25C ($2,000 heat pump credit) was repealed effective December 31, 2025 under the One Big Beautiful Bill Act (P.L. 119-21).
Re-verified when the underlying rule changes
- IRS Residential Clean Energy Credit (§25D) ↗
Internal Revenue Service
Confirms that §25D (30% credit for geothermal, solar, etc.) was repealed effective December 31, 2025 under the One Big Beautiful Bill Act (P.L. 119-21).
Re-verified when the underlying rule changes
- One Big Beautiful Bill Act (P.L. 119-21, signed July 4, 2025) ↗
U.S. Congress
Primary text for the federal residential energy credit repeals. Our reference for what changed and the effective dates.
Re-verified when the underlying rule changes
ENERGY STAR / cold-climate specification
- ENERGY STAR Cold-Climate Heat Pump (ccASHP) Specification ↗
EPA / DOE ENERGY STAR program
The ccASHP specification (70% capacity at 5°F, COP ≥ 1.75 at 5°F) that gates HPQPL listing and Mass Save eligibility.
Re-verified annually
EPA refrigerant transition
- EPA SNAP and AIM Act Refrigerant Rules ↗
U.S. Environmental Protection Agency
Federal phasedown of high-GWP refrigerants — context for the Jan 1, 2026 Mass Save R-410A removal and the transition to R-32 and R-454B.
Re-verified when the underlying rule changes
Utility tariffs (DPU filings + utility rate schedules)
- MA Department of Public Utilities Tariff Filings ↗
MA Department of Public Utilities
Published residential electric and gas tariffs for Eversource, National Grid, Unitil, Cape Light Compact, Berkshire Gas, and Liberty Utilities — source of the $/kWh and $/therm rates in our operating-cost calculator.
Re-verified quarterly
- Eversource MA Residential Electric Rate Schedule ↗
Eversource Energy
Current per-kWh delivery + supply rate used in the operating-cost calculator. Re-verified quarterly when DPU filings update.
Re-verified quarterly
- National Grid MA Residential Rates ↗
National Grid
Current per-kWh and per-therm rates for MA residential customers used in the operating-cost calculator.
Re-verified quarterly
Climate & weather data
- ASHRAE Climate Data Center & 99% Winter Design Temperatures ↗
ASHRAE
99% winter dry-bulb design temperatures by Massachusetts weather station — input to our sizing calculator and load estimator.
Re-verified annually
Building code & industry standards
- IECC 2021 Climate Zone Map ↗
International Code Council
IECC climate-zone designations (5A for most of MA, 6A for Berkshires/north-central) used in load calculations.
Re-verified when the underlying rule changes
- ACCA Manual J — Residential Load Calculation ↗
Air Conditioning Contractors of America
The industry-standard residential heating/cooling load calculation method that Mass Save requires for whole-home heat pump rebate filings. Our sizing calculator is calibrated against Manual J output.
Re-verified when the underlying rule changes
- 780 CMR 34.00 — MA State Building Code ↗
Commonwealth of Massachusetts
Permitting and inspection requirements for HVAC installation. Source for the per-city permit references on our city pages.
Re-verified when the underlying rule changes
- 310 CMR 12.00 — MA DEP Oil Tank Decommissioning ↗
MA Department of Environmental Protection
Underground oil tank closure requirements (soil testing, contamination protocols) — referenced on our oil-to-heat-pump conversion page.
Re-verified when the underlying rule changes
What we do not cite
- Affiliate-driven HVAC blogs that monetize through equipment referral links.
- Aggregator content (HomeAdvisor, Angi, Yelp) — opaque sourcing and no editorial standard.
- Generic "ultimate guide" listicles without primary-source references.
- AI-generated content from other sites (we can detect it; the citations don't trace back to first sources).
If you find an error
We post corrections in the Incentives Changelog with the date, the previous value, the new value, and the source that triggered the change. Send corrections through the contact form and reference the specific page and figure.
See also
Have a question about a specific figure?
Every dollar amount on MassHVAC traces to one of the sources above — but if a quote you got from a contractor doesn't match, we can help you sort out which number is right for your situation.