Off-Peak Electricity Timing in Ontario: Shifting Electric Heat Loads to Cheaper Hours

Electric heating · Published 2026-10-28 · Last updated 2026-10-28

General information only, not financial advice. Electricity prices, plan terms, and rebates change and differ by utility. Check the current prices and terms on your own utility's site before switching plans.

Direct answer first: for most homes that heat with electricity, Time-of-Use (TOU) pricing is the safer default, and the Ultra-Low Overnight (ULO) plan is a trap unless the household can genuinely keep evening heating down. The reason is timing. Laundry can wait until 2 a.m. Heat cannot. A house needs warmth at 7 a.m. when people get up and at 6 p.m. when they come home — and those are exactly the hours the plans price highest.

The current prices, with their dates

Rates in Ontario change on a cycle, and two rate years are circulating at once right now, so dates matter. For November 1, 2025 to October 31, 2026, Toronto Hydro lists TOU at 9.8 cents per kWh off-peak, 15.7 cents mid-peak, and 20.3 cents on-peak (s1). Off-peak means weeknights from 7 p.m. to 7 a.m., plus all day on weekends and holidays (s1).

Winter TOU on-peak hours are weekdays from 7 to 11 a.m. and from 5 to 7 p.m.; mid-peak runs from 11 a.m. to 5 p.m. on weekdays (s1) (s3).

ULO, for the same period, charges 3.9 cents per kWh overnight, from 11 p.m. to 7 a.m. daily — and 39.1 cents per kWh on-peak, on weekdays from 4 to 9 p.m., with mid-peak at 15.7 cents in the other daytime hours (s1). Read those two ULO numbers together. The overnight rate is strikingly low. The evening rate is close to double the TOU on-peak price.

The Ontario Electricity Rebate sits at 23.5% for November 1, 2025 to October 31, 2026 (s1). It is not part of the per-kWh comparison below, which uses the listed plan prices only — the timing math is what separates the plans, before any rebate is applied to a bill.

Two plans against a heating load

The worked example below uses a labelled assumption, not a claim about any real house: 1,000 kWh of electric heat in one winter month. Under TOU, assume half of that heat runs off-peak, 30% mid-peak, and 20% on-peak — a plausible split for a home that is occupied mornings and evenings and set back while empty.

Same heat. Same month. Under these assumed splits, ULO costs about $31.60 more, even though 400 kWh of it ran at the cheapest rate on offer. The evening block did that. On ULO, one quarter of the month's heat landing between 4 and 9 p.m. on weekdays costs $97.75 on its own — more than the entire off-peak and mid-peak portions combined in the TOU column.

Change the assumptions and the answer can change. A night-shift household that sleeps through the evening peak, or a very well-insulated home that can coast from 4 to 9 p.m. without calling for heat, pushes far more of its load overnight, and ULO is designed for households that can shift most usage to overnight hours (s3). The example is a method, not a verdict on every house: take the split from your own smart-meter data, not from a guess.

The ULO trap, priced one hour at a time

Shifting a single 100 kWh block shows the stakes more sharply than any monthly total.

Move 100 kWh of heat out of the ULO evening peak and into the overnight window, and the saving is 100 × (39.1¢ − 3.9¢) = $35.20. Move the same 100 kWh from TOU on-peak to TOU off-peak, and the saving is 100 × (20.3¢ − 9.8¢) = $10.50 (s1). ULO rewards shifting more than three times as hard — and punishes not shifting by the same factor. That asymmetry is the whole plan. For a car that charges while its owner sleeps, it is a gift. For baseboards warming a living room at 6 p.m. in January, the gift is pointed the other way.

Pre-heating: shifting heat without freezing

Heat has one property laundry does not: a building stores it, briefly. That makes a limited version of shifting possible.

1. Pre-heat before the expensive window. Raise the thermostat slightly in the cheaper hours just before a peak window, so the house enters the peak warmer than it needs to be.
2. Set back during the peak, not off. Lower the set point through the on-peak hours and let the stored heat carry the house. Turning heat fully off risks a long, expensive recovery — and frozen pipes in cold snaps are a far worse bill.
3. Recover in the cheaper window. Bring the temperature back up once prices drop, rather than the moment the peak ends if a mid-peak shoulder sits in between.
4. Check the result on meter data. After a week, look at how much consumption actually moved out of the peak window. If almost none did, the plan comparison should be rerun with the real split.

What success looks like: the house stays comfortable through the peak window, the thermostat is not calling for sustained heat during those hours, and the meter data shows the peak block shrinking week over week — not just the set point changing on paper.

Small loads still follow the old advice. Dishwashers, laundry, and other shiftable appliances are worth moving into off-peak hours under either plan. They are simply not where an electrically heated home's money is. Heat is the load that decides the plan.

November 1, 2026: the rates move, and so does the rebate

New Ontario Energy Board rates take effect November 1, 2026: TOU off-peak drops to 9.1 cents per kWh from 9.8, and on-peak drops to 18.9 cents from 20.3 (s2). ULO overnight drops to 3.7 cents from 3.9, and the ULO on-peak price drops to 37.7 cents from 39.1 (s2).

Do not bank the full drop. The Ontario Electricity Rebate falls from 23.5% to 15.7% at the same time, partially offsetting the rate decrease, and the OEB estimated the average household would save roughly $7.41 per month before that rebate change is counted (s2). The ranking between the plans does not change on November 1 — the ULO evening price is still roughly double the TOU on-peak price — but any dollar figure quoted from the current rate year expires on October 31, 2026. If a switching decision can wait a few days, run the comparison once on the new numbers.

When switching is not worth it

Skip the switch, whichever direction it points, in three situations. First, when nobody has looked at the household's actual hourly usage — a plan chosen on a guessed split is a coin flip. Second, when the home is occupied and heating hard through weekday evenings and nobody will accept a setback then; that usage pattern is the one ULO prices most harshly. Third, when the expected difference is a few dollars a month and the household will spend real attention policing thermostat times to earn it. Attention is a cost too.

The decision, reduced to one check: pull a winter month of hourly usage, price it under both plans at the rates dated above, and choose the cheaper one for the house as it actually lives — not as a laundry schedule says it should.

— Penny Hughes, Money Writer — Saving Desk