Quick answer: Air leakage causes about 20–30% of the heat lost from an older home, walls about 20% and basements about 20% (Natural Resources Canada). Ontario’s building code targets about R-60 attics in new homes, while the province’s attic rebate pays up to $1,250 to bring older attics to at least R-50. Nearly 1.2 million Ontario homes were built in 1960 or earlier (Statistics Canada).
Updated November 2026
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Key takeaways
- Older homes lose more heat through leaks, and Ontario has a lot of older homes.
- Rebates are biggest for the least-insulated attics.
- Federal grants have closed; Ontario’s Home Renovation Savings Program is the main source of rebates.
Heat loss and air leakage
- Air leakage represents about 20–30% of the heat lost from an older home. (Natural Resources Canada)
- NRCan estimates air-leakage heat loss in a 1950s home costs about $390 a year on natural gas or $860 on electricity. (Natural Resources Canada)
- For a home built 2000 or later, that estimate falls to about $280 on gas or $610 on electricity. (Natural Resources Canada)
- For a home built in the 1900s, it rises to about $720 on gas or $1,570 on electricity. (Natural Resources Canada)
- Walls can account for about 20% of a house’s heat loss. (Natural Resources Canada)
- A basement can account for about 20% of a home’s heat loss. (Natural Resources Canada)
- Windows, doors and skylights can account for up to 35% of total heat loss. (Natural Resources Canada)
- One small air leak can let in 100 times more moisture than diffusion through the same area. (Natural Resources Canada)
- In most houses, radiation accounts for less than 10% of heat loss; conduction and convection are the main causes. (Natural Resources Canada)
- More than 10% of Canada’s annual energy goes to heating homes. (Natural Resources Canada)
Building code and R-values
- Ontario’s building code (SB-12) targets about R-60 for ceilings with attic space in new homes in most of Ontario. (Ontario Building Code)
- Existing homes are not required to upgrade to current code levels. (Ontario Building Code)
- Upgrading an attic from R-12 to R-50 cuts heat flow through the insulation layer by about 76%; R-20 to R-60 cuts it by about 67%. (Pro Home Insulation calculation, simplified physics)
Housing stock
- In Ontario, nearly 1.2 million residential properties were built in 1960 or earlier. (Statistics Canada)
- Vermiculite from the Libby mine in Montana, sold in Canada as Zonolite® Attic Insulation, may contain amphibole asbestos; the ore was used until 1990. (Health Canada)
- Health Canada’s advice is to not disturb vermiculite insulation and to use qualified professionals for testing and removal. (Health Canada)
Rebates and programs
- Ontario’s Home Renovation Savings Program launched on January 28, 2025. (IESO)
- It is currently scheduled to run until March 31, 2027, after being extended in October 2026. (Enbridge Gas, as reported to contractors)
- The standalone attic path pays up to $1,250, with no energy assessment. (Home Renovation Savings Program)
- Attic path maximums rose by $250 across all tiers on January 5, 2026. (Home Renovation Savings Program)
- The attic rebate is 50% of the after-tax cost, up to the tier maximum. (Home Renovation Savings Program)
- The bundle path pays up to $7,700 for insulation, $600 for the energy assessment and up to $250 for air sealing. (Home Renovation Savings Program)
- Exterior wall insulation earns up to $3,600 on the bundle path. (Home Renovation Savings Program)
- The Canada Greener Homes Grant closed to new applications in February 2024; final documents were due December 31, 2025. (Natural Resources Canada)
- The Canada Greener Homes Loan stopped taking applications on October 1, 2025. (Natural Resources Canada)
Stats at a glance: where heat goes
| Part of the home | Share of heat loss (approx.) | Source |
|---|---|---|
| Air leakage (older home) | 20–30% | NRCan |
| Walls | About 20% | NRCan |
| Basement | About 20% | NRCan |
| Windows, doors, skylights | Up to 35% | NRCan |
These figures come from different sections of NRCan’s guidance and overlap, so they do not add up to 100%.
How to use these numbers
- Older home? Start with air sealing and the attic. They are usually the cheapest heat loss to fix.
- Planning several upgrades? Walls and basements are big heat-loss areas, and the bundle path pays more for them.
- Vermiculite? Do not disturb it. Get it tested first.
Citation
These statistics are free to use. Please credit “Ontario Home Insulation Statistics 2026, Pro Home Insulation” with a link to this page. Original sources are named on each line.
Frequently asked questions
How much heat does a typical home lose through the attic?
It depends on the home. Air leakage, much of it through the attic floor, accounts for about 20–30% of heat loss in older homes according to Natural Resources Canada. Upgrading from R-12 to R-50 cuts heat flow through the insulation layer by about 76%.
What R-value does Ontario require for attics?
Ontario’s building code targets about R-60 for attics in new homes in most of the province. Existing homes do not have to upgrade, but the attic rebate requires at least R-50.
How many Ontario homes are older?
Statistics Canada reports nearly 1.2 million residential properties in Ontario were built in 1960 or earlier.
Are these statistics updated?
We review this page when programs or sources change. The date at the top shows the latest update.
Talk to us about your home
Want to know where your home is losing heat? Call (647) 250-0606 or book a free attic assessment. See current programs on our rebates page.