House won't stay cool in summer
The AC runs all day, upstairs never cools, and July bills rival January's.
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What it usually means
- Attic heat load — a 60°C attic over a thin insulation layer is a radiant heater aimed at your bedrooms
- Duct leakage dumping cooled air into the attic or walls
- Aging or oversized AC short-cycling
What an audit measures
- Attic inspection + duct testing find the heat path
- Cooling load calculation right-sizes replacement equipment
Try first (cheap or free)
- Close blinds on south/west glass through afternoons
- Verify attic ventilation isn't blocked
The fix ladder
- Attic top-up + duct sealing
- Heat pump replacing the AC (cooling + heating in one)
Where you live changes the answer
Coastal BC
Most homes here were built without cooling, and the 2021 heat dome showed what that costs: 98% of BC's heat deaths happened indoors, mostly in homes without adequate cooling. Before the next heat wave, make sure at least one room can be kept cool (a heat pump or portable unit, shades on west and south windows, a fan), and check on neighbours who live alone.
Southern Ontario and the St. Lawrence valley
Summers are hot and humid, so cooling is as much about removing moisture as heat. An oversized air conditioner cools the air quickly but shuts off before it dries it, leaving rooms clammy; a cooling load calculation sizes a new air conditioner or heat pump properly, and Health Canada's 30% to 50% indoor humidity range is the target.
BC Interior, the Prairies and the North
Hot spells often come with wildfire smoke, so windows have to stay shut just when the house needs cooling. Plan cooling and filtration together: see the wildfire smoke guide.
Rebates that apply
- HRSP (with assessment) Ontario — Up to $10,000 per home ($5,000 if heated with Enbridge gas), including $600 back on your two assessments, for insulation, windows, air sealing and more — if the follow-up assessment is done by December 31, 2026
- HRSP (no assessment) Ontario — Heat pumps up to $7,500 ($12,000 ground-source), solar with battery up to $10,000, plus attic, thermostat and appliance rebates — no assessment needed
Outside Ontario? See the rebates in your province or territory →
Sources
Want it diagnosed properly?
A registered energy advisor measures instead of guessing — blower door, thermal imaging, and a written upgrade report priced against rebates.