Insulation ROI Calculator

How to Use the Insulation ROI Calculator

Insulation Upgrades in Canada: Which Assemblies Offer the Best Return?

Insulation is one of the more durable energy investments available to Canadian homeowners. Unlike mechanical equipment, which wears out and needs replacing, insulation keeps working for the life of the building once it is installed correctly. Which assembly gives the best return depends on the R-value it starts at, its area, and the local climate, which is what the calculator above compares.

Attic Insulation: The Highest-Return Upgrade

Attic insulation consistently ranks as a strong-value upgrade in Canadian homes, for three reasons. Most homes have large attic areas, often 100 to 200 m², so even a modest R-value gain touches a large surface. Existing attic insulation in pre-1980 homes is often R-12 to R-20, well below the R-50 to R-60 NRCan recommends now, so the improvement is large. And blown-in fibreglass or cellulose is one of the cheaper ways to add insulation, which keeps the cost per kWh saved favourable. Checking that added insulation against a real code target, rather than a rule of thumb, is what the R-value code checker does.

In the calculator above, a 120 m² attic going from R-20 to R-50 on gas at $0.35/m³ and 96% AFUE saves about $117 a year in Toronto and about $185 a year in Edmonton, where the colder climate does more of the work. Installed cost for blown cellulose typically runs $1,500 to $3,500, which puts payback in the 8 to 14 year range without any rebate on these figures. That combination of large area, a large starting gap, and low installed cost is what makes attic insulation a common first move in a Canadian retrofit, even without rebate help.

Basement Wall Insulation: The Second Priority

Basement walls are often uninsulated or barely insulated in pre-1990 Canadian homes, and NRCan estimates basements can account for around a fifth of a home’s total heat loss. Interior basement wall insulation with rigid foam and a studded wall carrying fibreglass batts is the common approach, and it typically reaches R-20 for $3,000 to $6,000 in a typical basement. This calculator models the starting point as effectively uninsulated when you enter no current R-value, and the savings figure it produces for that case runs well above what field studies of basement retrofits report, so treat the basement and rim joist numbers here as an upper bound rather than a firm estimate, and lean on a contractor’s heat-loss calculation before budgeting around them. Exterior basement insulation, which involves excavating, waterproofing, and adding foam outside the wall, costs more but also deals with moisture and thermal bridging at the same time.

The rim joist, the band of framing where the floor structure meets the top of the foundation wall, is worth calling out separately. It is often uninsulated and leaky, and spray foam applied there handles air sealing and insulation in one step, typically for $500 to $1,500 in a whole home. The same caution applies here as with basement walls: the savings this calculator shows for an uninsulated rim joist are on the high side of what a small, hard-to-model assembly like this usually delivers, so use them as a rough upper bound. Pair a rim joist job with a air changes per hour calculator reading before and after, since sealing this area often shows up more in blower-door results than in the utility bill alone.

Wall Insulation: Long Payback, Large Impact

Exterior wall insulation is the most expensive and disruptive envelope upgrade. Exterior continuous insulation, adding rigid foam over the existing sheathing and re-cladding, is the more effective approach but typically costs $15,000 to $40,000 for a full home. Interior wall insulation, furring out the walls and losing some floor area, runs less at $8,000 to $20,000. In the calculator, a 130 m² wall going from RSI 2.1 to 4.2 saves about $176 a year in Toronto and about $277 in Edmonton, which puts standalone payback well past the 25-year window this tool models, often 30 to over 100 years depending on the approach and city. Wall insulation on its own is rarely justified by energy savings alone. It tends to make financial sense only when the cladding or interior finishes are being replaced anyway, so the insulation cost is really the marginal cost over doing that work without it, not the full job priced separately.

What Happened to Canada Greener Homes

The Canada Greener Homes Grant is closed to new applicants, and the companion interest-free loan closed to new applications on October 1, 2025. While it ran, the program paid $210 to $5,000 for insulation depending on the assembly and area covered, with a household cap of $5,600 across every measure combined. A newer, income-tested program, the Canada Greener Homes Affordability Program, offers no-cost retrofits to low- and median-income households through provincial and territorial partners, but it is not a rebate on work you pay for yourself. For current provincial and utility rebates, use the rebate calculator, and see NRCan’s retrofit eligibility page for the full program history.