Cost tool
Energy Savings Estimator
Each upgrade is modelled as a percentage reduction in heating load, then converted to dollars against what you actually spend. Where a measure will not pay for itself, this says so.
No town pages are live yet in this state.
A cape has 12 to 16. A triple decker has 40 to 60.
Optional. Leave blank and we estimate it from size, fuel, and age.
Estimated annual savings
$306to$475
Heating load reduction
21% to 33%
Ten year cumulative
$3,060 to $4,750
Simple payback
10 to 16 years
- Add attic insulation
- $215 to $315
- Air seal
- $114 to $200
Usually the best return per dollar in this housing stock.
Cheapest measure, most overlooked.
Ranges are estimates for this market based on typical scope. They are not quotes. Actual pricing depends on the house, access, and what turns up once work starts.
Cost data reviewed 2026-09-01
How this is calculated
Every measure carries a documented range for how much heating load it removes. Those ranges are applied against your annual heating spend, or against an estimate built from square footage, fuel type, and the age of the house when you leave the spend blank.
Measures stack with diminishing returns. The first contributes at full value and each subsequent one at 80 percent of its standalone figure, because once the attic is insulated the windows have less to save. Total reduction is capped, because no envelope package eliminates heating load.
A regional heating degree day factor is applied from your town. The Berkshires and the Northwest Hills run meaningfully colder than the Cape or coastal Rhode Island, and the same upgrade saves more where there are more heating days.
One adjustment worth naming: if your windows are already double glazed, the model drops the window measure from the single pane figure to the much smaller realistic one. Replacing working double pane windows returns 4 to 7 percent, not 12 to 18.
What this tool cannot know
Every one of these matters to the final number and none of them can be read off a form. They are the reason the output is a range and the reason a contractor still has to look at the house.
- How leaky the house actually is, which a blower door test measures and a form cannot
- Whether the attic has adequate ventilation, which affects both comfort and ice dams
- What is genuinely in the wall cavity, since blown-in retrofits from the 1970s are common and vary in quality
- Your actual fuel price, which moves substantially year to year
Common questions
Because heat rises and the attic is where most of it leaves. Going from no insulation to a full depth cuts heating load by roughly 15 to 22 percent and costs a fraction of a whole house of windows. On most pre-1940 housing in this region it is the best return per dollar available.
Because sometimes that is the accurate answer, and this is a referral service rather than a contractor, so there is no product line to defend. If the payback runs past 25 years, the upgrade is not paying for itself on energy. There may still be good reasons to do it, and the tool names them.
Because program terms change, sometimes mid-year, and a wrong figure here would be worse than no figure. Mass Save, Energize CT, the Connecticut Green Bank, and Rhode Island Energy all run assessments and incentives worth pursuing. The panel links to each one so you can confirm current terms directly.
They are directional figures for typical New England housing, reviewed against the cost data on this site. They are ranges rather than single numbers because the actual result depends on how leaky your particular house is, which nobody knows without testing it.