Triple-deckers and multi-family homes
Three apartments, one building and often one very old service. Here is what comes up when an owner wants heat pumps, insulation or an insurer's sign-off.
- Checked: November 3, 2026
Heat pumps in a 1 to 4 unit building
Mass Save's whole-home heat pump rebate needs an individually metered 1-4 unit building or townhouse. A triple-decker may have one boiler for the whole building or a separate system per floor, and that changes the project. Send a photo of each boiler. See the calculator for the rebate rates.
The pieces
- The service that comes from the street to the building.
- The meter bank, with one meter per unit and often one for common areas.
- A panel in each unit, sometimes fuses in the older ones.
- The wiring inside the walls, which in a house of this age may include knob and tube.
Upgrading one of these usually means the others get looked at. The electrician sorts out the scope, and your utility is involved when the service or meters change. Ask who schedules the utility and the inspection.
What Mass Save says about 1 to 4 unit buildings
- Enhanced incentives: residents must live in a 1- to 4-unit home. If you are a renter, Mass Save encourages you to work with your landlord. Mass Save
- Whole-home heat pump rebate: equipment must be in an individually metered 1-4 unit building or townhouse. Mass Save
What Boston permits show
From 2025-11-01 to 2026-11-02, at least 230 Boston three-family permits and 785 one-or-two-family permits mention a service or panel change. At least 79 one-to-four-family permits mention meter banks or extra meters. See the permit data.
Questions to ask us
- Is this one service for the building or separate services per unit?
- What happens to each tenant's power during the work, and for how long?
- Does the meter bank need to be replaced or only reconnected?
- Can the knob and tube in each unit be checked in the same visit?
Thinking about heat? Read a heat pump for a triple-decker.
Common questions
Can you do all three units?
That is the usual question to ask. The electrician has to see the service, the meter bank and each unit panel before saying what is one job and what is three.
I am a tenant in a triple-decker. Can I send a request?
You can, but the owner has to approve electrical work on the building. Choose "I rent" in the form so we know.
Does Mass Save cover a three-family?
Mass Save says the enhanced incentives are for residents of a 1- to 4-unit home, and the whole-home heat pump rebate needs an individually metered 1-4 unit building. Ask Mass Save how your building and meters are treated.
Own a two or three family?
Send photos of the meters, the panels and the boilers. We look at them and get back to you.
Send photos