What a home energy assessment in southern Maine should measure, what the blower door number means, why combustion safety comes up in a tighter house, and how the findings turn into a list of jobs in the right order.
Our assessment is free: someone comes out, gets into the attic and the basement or crawl space, measures the insulation that is really there, looks for where the air is moving and photographs all of it. You get the photographs and a written scope whether or not you hire us.
A full energy audit goes further, with a blower door test, combustion safety checks and sometimes a computer model of the house. Efficiency Maine describes both on its own pages. This page explains what each test tells you, when the extra testing is worth having, how the rebate rules lean on it, and where a low-income household can get the whole thing for free.
A useful assessment answers three questions: how much insulation each part of the house has, where air is getting in and out, and whether anything has to be fixed before the work can start.
Efficiency Maine's audit page adds indoor air quality to the list: an energy advisor may recommend steps to reduce moisture or improve the air, and may flag radon or mold as health and safety items.
A blower door is a large fan fitted into an outside doorway. It pulls air out of the house until the inside sits at a set pressure below outdoors, and the amount of air the fan has to move to hold that pressure measures how leaky the house is, in cubic feet per minute at 50 pascals, written as CFM50. While the fan runs, a thermal camera or a smoke pencil shows where the outside air is coming in.
Efficiency Maine's rebate claim form has a box for that number before and after the work, and its checklist expects both tests on a rebated job unless a safety risk, a wood or pellet stove in use, or repairs in progress get in the way. The before number shows how much there is to gain; the after number shows what the sealing achieved.
New houses face a harder test. Maine's energy chapter lowered the air-leakage limit a new home must test at, and some towns here ask for the result: Harpswell wants blower door and radon results with every new home, and Waterboro inspects new homes with a blower door test.
Most homes in the three counties burn something for heat. By the Census Bureau's count, about half of occupied homes in Cumberland County and three in five in York County heat with fuel oil or kerosene, and many more with propane, gas or wood. A boiler, furnace or water heater with an open flue relies on the house to supply its air and on the chimney to carry the exhaust away.
Sealing a house changes both. That is why Efficiency Maine's audit page lists combustion safety testing on boilers and furnaces among the things an energy advisor does, and why its checklist requires, after rebated work, a spillage test on every open-flue appliance with the house depressurized: exhaust fans and the furnace running, flue dampers shut, and doors to rooms without exhaust fans closed. A warm appliance that keeps spilling exhaust beyond two minutes, or a cold one beyond five, gets reported to the homeowner.
The same checklist requires a carbon monoxide detector in the living space and may recommend mechanical ventilation once the house is tighter.
A thermal camera shows surface temperature, so on a cold day missing insulation in a wall or ceiling shows up as a warm patch from outside or a cold patch from inside. Efficiency Maine describes it as a way for trained users to find upgrade opportunities such as missing insulation. It works best with a real temperature difference between inside and out, which this climate supplies for much of the year: NOAA's 1991–2020 normals put 144 nights a year at or below freezing at the Portland Jetport.
In the attic, a tape measure does more than the camera. Measuring the depth in several spots, eaves included, and multiplying by the right factor for the material gives the R-value you have now, which is the number Efficiency Maine's rebate rules turn on: an attic qualifies only if it starts at an effective R-21 or less, and a wall or basement only at R-5 or less.
So the assessment reports measured numbers, not impressions, and says which zones are likely to qualify before you decide anything.
Efficiency Maine notes that some advisors produce extensive reports and computer models while others give a short checklist of the most important items. Either way, the useful part is the order. In most houses here it runs:
The proposal you get follows that order, with each item priced on its own line, the R-value each zone will reach, and which Efficiency Maine zones and tier it expects to qualify for. If the attic is already deep enough, it says so.
For households planning heat pumps, insulating and sealing first shrinks the heating load the new system has to meet; Efficiency Maine runs its heat pump rebates as a separate program.
MaineHousing's Weatherization Assistance Program starts with a free home energy assessment, and for eligible households the work that follows, air sealing and attic, wall, crawl space or basement insulation among it, is done at no cost. Eligibility often comes through the Home Energy Assistance Program, though some households qualify on the program's income limits alone; renters can apply with the owner's approval, and so can owners of small buildings of two to four units. A home weatherized in the last 15 years may have to wait.
It is delivered county by county by Community Action Agencies: Community Concepts for Cumberland County, Kennebec Valley Community Action Program for Sagadahoc County, and York County Community Action Corp for York County. Wait times depend on funding.
Households just over those limits may still qualify for Efficiency Maine's low or moderate tiers. It confirms them in advance, from a household member's enrollment in one of four assistance programs (HEAP, SNAP, TANF, MaineCare) or from tax records showing income no higher than $70,000 filing single or $100,000 filing jointly.
Our assessment measures the insulation, finds the main air leaks and photographs them, and ends in a written scope. A full audit adds a blower door test, combustion safety testing and sometimes a computer model of the house.
For a rebated insulation job, its checklist expects a test before and after the work, recorded on the claim form, unless a safety risk, a wood or pellet stove in use, or ongoing repairs prevent an accurate test.
A boiler, furnace or water heater with an open flue needs the house to supply its air and the chimney to draw. Tightening the house changes both, so Efficiency Maine requires a spillage test after rebated work.
Income-eligible households can, through MaineHousing's Weatherization Assistance Program, which begins with a free home energy assessment and does the work at no cost. Apply through your county's Community Action Agency.
Sealing and insulating first lowers the amount of heat the house needs, so the heat pumps have less to do. Efficiency Maine runs its heat pump rebates as a separate program from its insulation rebates.
Home energy assessment across greater Portland and southern Maine, from the Casco Bay islands to the York County coast and the Sebago Lake towns. Each city has its own page with the permit rule and code edition that apply there:
Sources: Energy audits: blower door, combustion safety, thermal camera, indoor air, reports · Blower door, smoke pencil, thermal camera; ventilation · Blower door before and after; spillage test; CO detector; ventilation; R-21 and R-5 limits · Pre- and post-upgrade CFM50 on the claim form · Maine's air-leakage change for new homes · Weatherization Assistance Program: free assessment, eligibility · Community Action Agencies by county · Low and moderate income verification · Heating fuel by county (B25040) · Portland Jetport freezing nights · Rebate zones and conditions. Codes, programs and prices change; confirm the current rule with your city before you rely on it.
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