Key Takeaways
•The short answer: In a hypothetical Boston three-decker, moving a $6,000 owner-paid heating bill onto tenants' own meters adds $6,000 to net operating income. At cap rates of 4.5% to 5.64% from the named sources below, that is worth about $106,000 to $133,000 in building value, before any rent concession (a rent cut that may come with tenant-paid heat).
•The legal trap: Sub-metering heat off a shared boiler runs into state rules. Mass.gov says electric submetering is generally prohibited in Massachusetts because it is resale of electricity. A 1997 Department of Public Health opinion letter reads the Sanitary Code to mean a tenant pays for gas or electricity only through a meter that serves that unit alone. The one sub-metering statute I found, M.G.L. c.186, s.22, covers water only.
•The possible winner: Heat pumps on each unit's own electric meter can remove the owner's heat bill and add cooling, but only if a utility rate review confirms how each meter will be billed.
•The bottom line: In this example, heat pumps and split boilers can each move the heat bill onto tenants' meters. Which one pays back depends on the rate review, the installed cost, and when leases allow the change.
What Is One Heating Bill Worth to a Building's Value?
Take a hypothetical 1910 three-decker with one basement boiler and one owner-paid heating bill of about $6,000 a year. The $6,000 is an illustration, not a quoted utility bill. Every figure below follows from it.
A building's value tracks its net operating income, or NOI: yearly rent minus operating costs, before the mortgage. Buyers divide NOI by a cap rate, which is NOI as a share of price. I found no published cap rate for three-deckers alone, so this example uses rows from two sources. RealCostIQ's Boston page (read Oct. 27, 2026) lists 4.5% to 4.75%, which it takes from CBRE's H2 2025 figures for Class A, stabilized, infill apartment buildings. Apartment Loan Store's Boston table (as of Oct. 27, 2026) lists 5.10% and 5.64% for its Class B and Class C metro multifamily rows. The DSCR article on this site uses the 5.10% row. Class labels are each source's own.
Dividing $6,000 by each cap rate gives about $133,000 (4.5%), $126,000 (4.75%), $118,000 (5.10%) and $106,000 (5.64%) of building value (my calculation).
For comparison, adding the same $6,000 of NOI through rent alone would take a combined $500 a month across the three units, about $167 each. A heating change removes a cost instead of depending on a rent increase.
That range is a ceiling, not a forecast. Suppose tenants who start paying their own heat negotiate $50 a month off rent per unit. That is $1,800 a year across three units, which cuts the $6,000 to $4,200. At the same four cap rates, $4,200 is worth about $93,000, $88,000, $82,000 and $74,000 (my calculation). The $50 is a hypothetical, and a real building's rent concession would replace it.
Timing matters too. An RMI brief (Aug. 26, 2026) reports that residential heat-pump electric rates became available from all three Massachusetts electric utilities (Eversource, Unitil and National Grid) on Nov. 1, 2025. Mass.gov says eligible customers pay lower distribution and transmission charges from Nov. 1 through Apr. 30 (read Oct. 27, 2026). This November marks the second winter under those rates.
What Are the Three Ways to Move the Heat Bill Off the Owner?
Sub-metering: The owner keeps the central boiler and adds meters that split usage among units. This is the cheapest hardware, and the state sources speak to it directly. Mass.gov says electric submetering is generally prohibited in Massachusetts (read Oct. 27, 2026). The Sanitary Code (105 CMR 410.200) says an owner provides gas or electricity unless a meter that serves only that unit measures it and a written rental agreement makes the occupant pay. A 1997 Department of Public Health opinion letter, written about landlord-run gas measurement for heat and hot water, reads "meter" to mean a utility-installed one. An RMI brief (Aug. 26, 2026) says the same in a footnote. I found no Massachusetts rule that allows sub-metering heat. The only sub-metering statute, M.G.L. c.186, s.22, covers water. Whether a particular shared-boiler setup fits is a question for a landlord-tenant attorney.
Split boilers: Each unit gets its own boiler and gas meter, and tenants pay the utility directly. That is consistent with the single-unit meter wording of 105 CMR 410.200, but it is heavier work: three appliances, three vent runs through an old building, and three systems to maintain.
Heat pumps: Each unit gets electric heat pumps on its own electric meter. Tenants pay the utility, and the building gains cooling. RMI's brief "Caught Between Rate Classes" (Aug. 26, 2026) found that electric rate eligibility changed costs more than many design choices in its case study, a hypothetical 53-unit Massachusetts building. RMI calls metering configuration a key factor in which electric rates a building can access.
Two tests apply to any quote:
1. Payback: net installed cost after rebates ÷ $6,000 = years to earn it back.
2. Value: if net cost comes in below the value range above (about $106,000 to $133,000 here), minus any rent concession, the project adds to building value once the expense disappears.
Mass Save's 2026 whole-home air source heat pump rebate is $2,650 per ton, up to $8,500, for systems installed in 2026. For systems installed on or after Jan. 1, 2027, it drops to $2,350 per ton, capped at $7,500 (Mass Save, read Oct. 27, 2026). The Mass Save HEAT Loan offers 0% financing up to $25,000 total for qualifying upgrades, and the loan applicant must be the homeowner. The rebate page lists eligibility rules, including one whole-home rebate per account.
In this example, heat pumps win on value only if the rate review checks out. Split boilers do not depend on an electric rate review. Sub-metering looks cheapest on paper, and the state sources above point to the most legal risk.
What Does Massachusetts Let a Landlord Bill, and When?
If current leases include heat, new equipment does not change that agreement by itself. Whether a lease locks the arrangement until renewal or a new lease, and what notice a landlord must give before tenants take over a bill, are questions for a landlord-tenant attorney. The wording of any notice is also a legal question.
How a heat charge appears on a rent statement is a further question for an attorney. A homemade heat split can raise billing disputes of its own.
Ratio billing divides one shared bill by square footage or bedroom count, with no unit meters. Under 105 CMR 410.200, tenant-paid gas or electricity is tied to a meter that serves only that unit, so ratio billing is a question to clear with an attorney first.
Won't Tenants Just Pay Less Rent?
Some pushback is real. If heat was included before, tenants may expect a rent cut once they pay the utility directly. That is why the concession is part of the value math above.
RMI's brief notes that tenants can be more conservative in their usage when they pay for their own utilities. Heat pumps also add cooling. Across the Boston-Cambridge-Newton metro, the April 2023 MAPC/Emerald Cities report, using 2021 American Housing Survey data, estimates that 77% of homes in 2-4 unit buildings use room air conditioners and 23% use central AC.
Air Conditioning Type by Housing Typology in the Boston-Cambridge-Newton MSA
Central versus room air conditioning shares for selected housing typologies in the Boston-Cambridge-Newton MSA.
1-unit
2–4 units
| Series | Label | Value |
|---|---|---|
| Central AC | 1-unit | 50% |
| Room AC | 1-unit | 50% |
| Central AC | 2–4 units | 23% |
| Room AC | 2–4 units | 77% |
Source:FINAL REPORT
For an owner, that gap is one place heat pumps differ from boiler options: they add cooling to a stock where most 2-4 unit homes use room units. This data does not measure whether that changes rent or resale value.
Could a 1910 Building Blow the Budget?
Yes. This is the fair objection.
Old wiring, weak electric service, chimney liners, and asbestos-wrapped pipes can stretch payback out. Lead is another risk. EPA estimates, cited in the April 2023 MAPC/Emerald Cities report, say 87% of homes built before 1940 are likely to contain lead-based paint. That is a national figure, not a Boston one (EPA, read Oct. 27, 2026).
This is where the value test helps. Say surprises push net cost to $60,000. At $6,000 a year, that is a 10-year payback, which looks slow. But $60,000 is below the $106,000 low end of the value range above, and below the $74,000 low end after a $50-per-unit rent cut.
If wiring, venting, and abatement push net cost past that value range, the project loses money. Averages cannot show that; only quotes for the specific building can.
Do Heat Pumps Just Push the Cost Onto Tenants?
They can, if the rate setup is wrong. In RMI's case study, otherwise similar buildings faced different electricity costs depending on which rate class they could access.
Savings from a heat pump depend on the fuel it replaces and the electric rate. The Massachusetts Department of Energy Resources (DOER) said in its winter heating report, published Nov. 10, 2025, that households should not assume switching fuels will automatically save money. It estimated that households on the new seasonal heat pump rate could save about $540 on heating bills that winter (Mass.gov, read Oct. 27, 2026). If a tenant's electric bill rises, the owner may end up giving back rent, which cuts into the savings.
A heat-pump rate review covers:
•which meter serves each unit,
•which rate class applies,
•whether the heat-pump rate is actually available,
•and what the bill looks like in winter.
If the review shows a mismatch between the meter setup and the rate, the heat-pump case weakens. Split boilers do not depend on an electric rate.
Why Not Just Upgrade the Boiler and Air-Seal?
Air-sealing, insulation, and a better boiler can trim the bill without lease complications, since the landlord still provides heat.
But efficiency only shrinks the line item. Separation removes it, and because value is NOI divided by the cap rate, that difference moves building value more. If an attorney finds tenant-paid heat does not fit a building, efficiency is the remaining route.
What Does a Heating Review Cover Before the First Nor'easter?
1. A utility rate review. It confirms which heat-pump rate class applies to each unit's meter.
2. A side-by-side price. Heat pumps and split boilers are run through the payback and value tests, with a realistic rent concession included.
3. A legal screen. Heat sub-metering and ratio billing both run into the state rules above, so they are questions for an attorney, not cost savings.
4. Lease timing. An attorney can set when the switch fits renewals and what heat terms go in writing.
A buyer pricing a building on its income counts a $6,000 heat bill as an expense, so a three-decker without it shows higher NOI in this example.
Heat pumps add value in this example only if the rate review checks out. Split boilers do not depend on that review. Sub-metering is the cheapest hardware, and the state sources above leave it the most legally uncertain.
To test a specific building, send me the address, the last 12 months of heat bills, the current leases, and the electric meter setup. I'll run the numbers on it.
This article is general information, not legal or tax advice. Talk to your CPA and attorney about your own situation.
