Thermostat TOU Scheduling Ontario 2026: The Schedule That Actually Saves Money on Time-of-Use and ULO

2026 Ontario TOU and ULO Timing Recap

Before you program a single thermostat, you need to know exactly when the expensive windows are. The Ontario Energy Board sets regulated rates and windows for residential customers on the Regulated Price Plan, and the rates below are current for the winter season running November 1, 2025 through April 30, 2026.[1]

The single most important move is to stop running heating or cooling equipment harder than necessary during the 20.3 cent TOU on-peak and the 39.1 cent ULO on-peak windows. A good thermostat schedule earns back the device cost in the first year on most Ontario homes.[3]For the full rate picture and how it compares to the tiered plan, see our Ontario electricity rates guide.

Target Schedule for Winter TOU

The winter pattern is double-peaked: a morning spike from 7 to 11 a.m. when people get up and start showering, and an evening spike from 5 to 7 p.m. when dinner cooking and lighting hit the grid. Your thermostat should do the opposite: recover the house before 7 a.m., drift down through on-peak, recover again for mid-peak, drift through the evening on-peak, then hold a comfortable setting overnight.

If you work from home and cannot run the house at 64 F during weekday mornings, lift the on-peak setpoint to 66 F and accept the smaller savings. The schedule should match how you actually live, not a theoretical model. Weekend programming should mirror the off-peak pattern all day since weekends are off-peak under TOU.

Target Schedule for Summer TOU

The summer window flips. On-peak is the middle of the day, 11 a.m. to 5 p.m., which is exactly when cooling load is heaviest because the sun is on the house. That means pre-cooling matters more in summer than pre-heating does in winter.

Pre-cooling is the single biggest lever in summer. A well-insulated house that is cooled to 70 F by 11 a.m. will usually drift to 75 or 76 F by 4 p.m. with almost no compressor runtime on anything but the worst heat wave days. That takes the expensive 20.3 cent window almost entirely out of the bill.

Target Schedule for ULO

The Ultra-Low Overnight plan rewards households that can move load into the 11 p.m. to 7 a.m. window. At 3.9 cents per kWh overnight versus 39.1 cents on-peak weekdays, the price ratio is 10 to 1. A ULO thermostat schedule pushes every discretionary minute of equipment runtime into overnight and sharply limits on-peak runtime.[7]

ULO is the right plan for EV drivers, heat pump owners whose load concentrates overnight, and households with large thermal mass (brick exterior, poured concrete basements, thick interior partitions) that can hold a pre-conditioned temperature for hours. It is the wrong plan for small electrically heated apartments where load is flat all day.

Pre-Cooling and Pre-Heating Strategies

Pre-conditioning works because the building envelope acts as a battery. You spend cheap kWh filling the battery (cooling down the drywall, floors, and furniture in summer, warming them in winter), then draw the battery down during the expensive window while the equipment idles.

Three rules make pre-conditioning actually pay off:

• Insulation has to be decent. If the house loses 3 degrees of pre-cool in an hour, you cannot carry it through a 6 hour on-peak window. Pre-cooling helps most in homes with blown attic insulation at or above R-50 and reasonable window coverings. For more on envelope performance, see ourwinter heating bills guide.
• The pre-condition swing needs to be large enough to matter. A 1 degree pre-cool will not carry the house. Plan for 2 to 3 degrees below normal setpoint in the last hour of mid-peak, and 3 to 4 degrees for ULO pre-conditioning overnight.
• The drift target during on-peak needs to be wide enough that the compressor or burner does not cycle on during the expensive window. For cooling, 78 F is a realistic drift target. For heating, 64 F is the typical floor.

Setback Degree Recommendations

The long-standing rule for conventional equipment is that a setback of about 5 degrees Fahrenheit (roughly 3 degrees Celsius) held for four or more hours produces 10 to 15 percent savings on heating or cooling runtime in that window without making the house uncomfortable on the return.

The sleep setback at night is usually the biggest single contributor to savings because it runs for 7 or 8 hours and covers a large slice of total equipment runtime. Most occupants sleep better at 63 to 65 F anyway.

Heat Pump Exception: Why Aggressive Setbacks Can Cost More

Here is where conventional wisdom fails. Air-source heat pumps are sized to cover the design heating load at steady state with the compressor only. When the indoor temperature drops too far, two things happen that penalize you: the coefficient of performance degrades because the indoor coil is working against a larger indoor-outdoor delta, and the thermostat often invokes auxiliary electric resistance heat to force a fast recovery.[8]

Resistance heat runs at a COP of 1.0. Every kWh of electricity produces exactly one kWh of heat. The compressor it replaced was running at a COP of 2.5 to 3.5. That means a 30 minute recovery burn on auxiliary heat uses the same electricity as 75 to 90 minutes of compressor-only operation would have.

Ontario specific math makes this worse. On a ULO plan, if the recovery burn happens between 7 and 11 a.m. at 39.1 cents per kWh, a 3 kW auxiliary strip running for 30 minutes costs about 59 cents. The compressor-only recovery that started an hour earlier at 3.9 cents per kWh would have cost about 8 cents for the same heat delivered. That is roughly a 7 to 1 cost ratio on a single recovery event.

The solution for heat pump owners is three-part:

• Keep setbacks small, typically 2 to 3 degrees F.
• Enable adaptive recovery in the thermostat so the equipment starts ramping up gently an hour or more before the occupied setpoint is required. Nest calls this True Radiant. Ecobee calls it Smart Recovery. Honeywell calls it Adaptive Intelligent Recovery. They all do the same thing.
• If the installer wired a separate call for auxiliary heat, make sure the lockout temperature is set high enough (for example, do not allow aux heat above 30 F outdoor) so the compressor gets first shot at every recovery.

For more on heat pump sizing and operating cost in Ontario, see oursmart thermostat cost guide, which walks through the device options and the installed cost math.

Setting Schedules on Nest, Ecobee, and Honeywell

All three major smart thermostats sold in Ontario can be programmed to the TOU or ULO schedule above, but each has quirks that catch people out.

Google Nest

Nest learns from your behaviour and will override your manual schedule if it decides you are home or away. To lock in a TOU schedule, turn off Auto-Schedule in the Nest app settings, then build the schedule manually under the Schedule tab. Use six setpoints per day matching the windows above. Enable True Radiant for adaptive recovery. Disable Home/Away Assist if you want the schedule to run regardless of sensor readings, or leave it on and accept that the thermostat will drift to Eco temperatures when it thinks the house is empty.[4]

Ecobee

Ecobee has the most granular programming of the three. Build named comfort settings (Home, Sleep, Pre-Cool, Drift, Recover) in the app, then assign them to hourly slots Monday through Friday and separately for weekends. Enable Smart Recovery in the General settings so the equipment starts early enough to hit setpoint at the scheduled time. If you have remote sensors in bedrooms, set the Sleep comfort profile to follow only the bedroom sensor so you are not heating or cooling the whole house to suit one room.[5]

Honeywell Home (Resideo)

The T-series and Lyric thermostats support seven-day programming with four daily periods (Wake, Away, Home, Sleep). That is enough for TOU but tight for ULO, which benefits from six distinct periods. If you need more granularity, upgrade to the Honeywell T9 or use the Resideo Pro app with a schedule programmed period by period. Enable Adaptive Intelligent Recovery so the equipment starts early to hit the next scheduled setpoint on time.[6]

Utility demand response programs

Save on Energy runs a demand response program that can cycle your AC or heat pump automatically during summer on-peak periods called by the IESO. Enrolment is free, you get a modest annual credit, and the cycling events are short (typically under four hours). If you are already running a pre-cool plus drift schedule, the cycling usually has no noticeable comfort impact because the house is already coasting on thermal mass.[3]

Frequently Asked Questions