Updated October 3, 2026 · DF Property Management
The heat rule: 21°C, October 1 to May 15
Under Toronto's Heating by-law, where the landlord supplies heat, rental units must be kept at a minimum of 21°C from October 1 to May 15. The temperature must be maintained in all areas of the unit, not just near the thermostat.
These dates are new. Until April 30, 2025, Toronto's heating season ran from September 15 to June 1. Council shortened it at the same time as it lengthened the cooling season. Many leases, building manuals and online articles still quote the old dates.
The City also says that if the weather outside keeps a building at 21°C without heat, landlords can turn the heat down or off.
The provincial layer
The Residential Tenancies Act treats heat as a vital service from September 1 to June 15, and landlords may not withhold it during that period. Ontario's provincial maintenance standards, which apply where no municipal property standards by-law exists, set a 20°C minimum over the same months. In Toronto, the City's 21°C rule is the one inspectors enforce. But don't read the October 1 start date as permission to leave the boiler off through a cold September week.
Who it applies to
- Landlord-supplied heat — the usual case in older apartment buildings and many plexes. The landlord must meet 21°C.
- Tenant-controlled heat paid by the tenant — for example, a condo unit with its own furnace. The landlord must keep the equipment working, but doesn't control the thermostat.
- Shared systems — a house with a main unit and a basement suite on one furnace. Whoever controls the thermostat needs to keep the coldest unit at 21°C. Write it into the lease.
Air conditioning: June 1 to September 30
Toronto does not require landlords to install air conditioning where it doesn't already exist. But where the landlord supplies it:
- It must be operated from June 1 to September 30, keeping units at no more than 26°C.
- Before the 2025 change, the period was June 2 to September 14.
Since June 1, 2026, apartment buildings in the RentSafeTO program that don't provide cooling in every unit, but do have an indoor amenity space, must keep at least one such space at or below 26°C from June 1 to September 30 — unless construction would be needed to do it. The nearest cooling location also has to be posted on the tenant notification board.
Window units
City by-laws don't prohibit window air conditioners in apartment buildings. Owners are responsible for making sure they are installed and maintained safely: properly supported, not blocking a fire escape, and not dripping onto the units or sidewalk below. Many buildings set out window unit rules in an additional lease term or building policy.
A maximum temperature by-law is coming
In June 2026, Council directed staff to speed up work on a by-law that would set a maximum indoor temperature for rental units, including those without air conditioning. As of October 2026 it is not in force, and the timing is still to be set. Owners of older towers in places like St. James Town or Thorncliffe Park should start costing cooling options now, as part of the capital plan.
Vital services: never cut them off
Toronto's vital services rules cover fuel, hydro, gas, and hot or cold water, plus heat in season. The key points:
- A landlord can't withhold a vital service for any reason — not for unpaid rent, not for damage, not to pressure a tenant to leave.
- A utility supplier must give the City at least 30 days' written notice before cutting off a rental property because the landlord broke its contract — for example, by not paying the gas bill.
- The City can direct the supplier to restore service, and under the City of Toronto Act, 2006 can recover the cost from the owner, including by adding it to the property tax roll.
- Under the RTA, withholding a vital service is an offence. Maximum fines are $50,000 for an individual and $250,000 for a corporation, and the tenant can also apply to the Landlord and Tenant Board.
Houses and plexes: put it in the lease
Most heat disputes in small properties come from vague leases, not cold weather. The Ontario Standard Lease asks who is responsible for heat, electricity and water. Answer precisely, and use the additional terms to cover the details:
- Which unit controls the thermostat, and the minimum setting it must hold during the heating season.
- Who pays for gas and hydro when one meter serves two units, and how the bill is split.
- Who replaces furnace filters, and how often.
- Whether space heaters are allowed. They can overload old circuits and are a common cause of fires.
- Who supplies and maintains any air conditioning, and when it will be turned on.
How complaints are enforced
- Tenant contacts the landlord — the City expects tenants to go to the landlord first. In RentSafeTO buildings, "no heat" is an urgent request with a 24-hour response time; "low heat" has seven days.
- Tenant calls 311 — if nothing happens. Tenants are asked whether their unit has air conditioning, which decides whether a summer complaint is enforceable.
- Inspection — a Municipal Licensing & Standards officer measures temperatures in the unit.
- Order and follow-up — orders to comply, re-inspection, and charges if the problem continues.
A seasonal checklist for owners
- August: boiler or furnace service, combustion check, replace filters, bleed radiators, test the building automation and outdoor-reset settings.
- September: be ready to fire up early. Heat counts as a vital service from September 1.
- October 1 to May 15: spot-check corner units, top floors and units over garages — they fail first.
- May: service chillers, cooling towers or PTAC units; check window unit installations.
- June 1 to September 30: run landlord-supplied cooling to 26°C; keep the amenity room cool if the RentSafeTO rule applies.
- All year: log every heat and cooling complaint with the date, the reading, and the fix.
How we help
Our maintenance team runs a 24/7 line for no-heat calls and schedules seasonal servicing before the dates arrive, not after. For apartment buildings we track temperature complaints against the RentSafeTO clocks and fold cooling upgrades into capital planning. Owners across Toronto get photos and invoices for every visit.
General information, not legal advice. Toronto's heating and cooling requirements were amended in 2025 and a maximum temperature by-law is in development; confirm the current rules with the City of Toronto.