Is Your Home Ready for a Heat Pump? Insulation, Air Sealing and WAP Eligibility

By Max Fisher · Published 2026-10-22 · Updated 2026-10-24

Short answer. A heat pump can only keep up with a house that holds its heat. Air leaks and thin insulation raise the amount of heat the house loses on the coldest day, which pushes heat pump installers toward bigger equipment and leaves the system running longer and leaning on backup heat. Measuring the house, sealing it and insulating it before sizing the system is a sequence the Department of Energy and ENERGY STAR both describe. If your household qualifies on income, Maryland’s Weatherization Assistance Program (WAP) can do much of that work at no cost.

Why the house matters more than the brand

Every heating system replaces the heat a house loses. The difference with a heat pump is that its capacity is not unlimited on a cold night. A cold-climate model sized correctly for a sealed, insulated house can carry most of the winter by itself. The same model in a drafty house reaches its limit sooner, hands off to backup heat more often and costs more to run. None of that is a flaw in the heat pump. It is the house.

That is also why sizing has to come after the envelope work. A load calculation done on today’s leaky house will call for more capacity than the house needs after sealing and insulation. ACCA’s Manual J is the standard method, and it is only as good as the house it describes. See how heat pumps work for the balance-point side of this.

Get the house measured, not guessed

An energy audit is a measurement, not a walk-through. The core test is the blower door. The Building America Solution Center describes it as a test that measures how much air leaks through a house’s shell and reports the result in standard units that codes and energy programs use. The DOE’s air sealing guide adds that assessors use a blower door and a thermal camera to find leaks, and names the two national certifications to look for: BPI Building Analyst and RESNET HERS Rater.

A real assessment typically looks at:

Air leakage. Measured with the blower door, then traced to its sources. The DOE guide maps 19 key areas, and many of the big ones are hidden in the attic, the basement and around chimneys and fixtures, not at the windows.
Attic insulation. Depth, type and gaps.
Walls and floors. Harder to see without a thermal camera or small inspection holes.
Ducts. ENERGY STAR estimates that typical ducts lose about 20 to 30 percent of the air moving through them to leaks, holes and poor connections. Ducts running through an attic or crawl space lose heat before it reaches a room.
Combustion safety. If the house has gas or oil appliances, see the next section.

In Maryland, the assessment is also the front door to utility rebates. BGE and Pepco both start their Home Performance with ENERGY STAR programs with an assessment by a participating contractor. See home energy assessment and the rebate stack.

Sealing comes first, with one safety check before it

The DOE guide’s picture is a good one: insulation is a sweater, air sealing is a windbreaker. A sweater keeps you warm in still air, but it does not stop the wind. Sealing first means the insulation that goes in next works as rated.

There is one step before sealing. ENERGY STAR warns that sealing a house can cause combustion appliances, such as a gas water heater or an oil furnace, to backdraft, pulling exhaust back into the living space. Those appliances should be checked, and fixed if needed, before the house is tightened. ENERGY STAR also notes that a very tight house may need mechanical ventilation. A good auditor tests for both.

After sealing, insulation. ENERGY STAR’s attic recommendation is the same for climate zones 4A and 5 (check its map for your exact zone): R-60 for an uninsulated attic, or R-49 added on top of 3 to 4 inches of existing insulation. ENERGY STAR estimates that air sealing plus insulation saves homeowners an average of 15 percent on heating and cooling costs. BGE requires attic air sealing and attic insulation to R-49 for its heating and cooling equipment rebates.

Not every house needs this work. A newer, already tight house may go straight to sizing. The audit tells you which kind of house you have. The full step-by-step is in the air sealing and attic insulation guides.

Maryland’s Weatherization Assistance Program

WAP is funded through the U.S. Department of Energy and run in Maryland by the Department of Housing and Community Development (DHCD) through local weatherization agencies. Nationally, the DOE says the program weatherizes about 32,000 homes a year with DOE funds, that households save an average of $372 or more a year according to a national evaluation, and that it has served more than 7.2 million families since 1976.

Who it serves. Homeowners and renters both. DHCD gives priority to households with someone over 60, people with disabilities, children in the home, and households with high energy use or energy burden.

Income limits. DHCD posts limits based on 60 percent of state median income, but not lower than 200 percent of the federal poverty level. The table DHCD showed on this page’s publication date (updated February 11, 2026):

Household size	Income limit
1	$48,085
2	$62,880
3	$77,675
4	$92,470
5	$107,265
6	$122,064

Limits change, so check DHCD’s WAP page for the current table and larger households.

Automatic income eligibility. DHCD accepts current participation in utility bill pay assistance through the Office of Home Energy Programs, SNAP, TANF, SSI or HUD housing assistance. It does not accept Medicaid, fuel fund assistance or DHCD rehab programs as proof.

What the work can include. After eligibility is confirmed, the local agency schedules an energy audit. Depending on the house, work can include blower-door air infiltration reduction, attic, floor and wall insulation, hot water improvements, lighting, furnace cleaning, tuning, safety repairs or replacement, and health and safety items.

How to apply. Contact your local weatherization agency, listed on DHCD’s page, or call DHCD’s Maryland-only toll-free line, 1-855-583-8976. An application has to be submitted before any service.

Questions to ask the auditor

“Will you run a blower door test, and will I get the number in writing?”
“Which certification do you hold: BPI Building Analyst or RESNET HERS Rater?”
“Will you test my gas or oil appliances for backdrafting before and after sealing?”
“Which leaks and insulation gaps would you fix first, and why?”
“Does this audit qualify for my utility’s rebate program?”

What this means for you

Get a blower-door audit before you collect heat pump quotes. It changes the size you need.
Have combustion appliances checked before sealing.
If you might qualify, apply for WAP before paying for weatherization yourself.
Hand your audit report to every installer who quotes, and ask how it changed their sizing.

How to verify this yourself

DHCD: Weatherization Assistance Program
DOE: Weatherization Assistance Program and the air sealing guide
ENERGY STAR: find the problems you want to fix and duct sealing

Tell us if a source changes. To find companies that list energy audits and air sealing, see the energy audits and air sealing service page.