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The most common question after a Toronto heat pump install is some version of: "what does this do to my hydro bill?" The honest answer requires four numbers — Toronto Hydro Ultra-Low Overnight (ULO) rates, the home's heating and cooling load, the heat pump's seasonal COP, and the household's willingness to schedule consumption away from on-peak windows. This post walks through real month-by-month projections for a typical Toronto semi, with the pre-conditioning strategy that takes the most cost out of the bill.
For the full conversion guide, see Heat Pump Conversion Toronto: The Complete 2026 Guide. For the gas-vs-heat-pump comparison, see Heat Pump vs Gas Furnace Toronto Comparison.
RenoHouse Role
We coordinate heat pump retrofits with TSSA-G2-licensed and HVAC-licensed installers. The bill projections below come from real Toronto installs we have observed across 2024-2026 — with the caveat that household behaviour drives a wide spread (50%+ swing depending on rate-plan management).
Toronto Hydro 2026 Rate Plans
Three plans available to residential Toronto Hydro customers:
| Plan | Off-Peak | Mid-Peak | On-Peak | Best For |
|---|---|---|---|---|
| Time-of-Use (TOU) | 7.4 cents/kWh | 10.2 cents/kWh | 15.8 cents/kWh | Standard households |
| Tiered | 10.3 cents/kWh up to 1,000 kWh, then 12.5 | n/a | n/a | Low-usage, predictable |
| Ultra-Low Overnight (ULO) | 2.4 cents/kWh (11pm-7am) | 9.5 cents/kWh | 28.4 cents/kWh (4-9pm wkday) | Heat pump + EV households |
Plus delivery and regulatory charges of roughly 4-5 cents/kWh blended fixed.
For a heat pump household, ULO is the right plan if (and only if) you can shift 60%+ of HVAC load to overnight or mid-peak hours. Otherwise TOU or Tiered may be better.
The Reference Home
For grounded numbers, we use a 2,000 sqft semi-detached in East York, built 1968, with R-30 attic post-retrofit, R-12 walls, double-glazed windows. Annual heating load 85 GJ, cooling load 14 GJ, plus baseline electric load (lighting, plug, appliances, water heater) of 6,500 kWh/year.
Before: Gas Furnace + AC Baseline
Annual energy bills before heat pump conversion:
| Category | Quantity | Unit Cost | Annual |
|---|---|---|---|
| Gas heating | 2,300 m3 | $0.35/m3 | $805 |
| Gas standing charge | 12 mo | $20/mo | $240 |
| Electric AC | 1,000 kWh | $0.135/kWh blended TOU | $135 |
| Baseline electric | 6,500 kWh | $0.135/kWh blended | $878 |
| Electric standing charge | 12 mo | $25/mo | $300 |
| Total annual | — | — | $2,358 |
Monthly average: $196.
After: Cold-Climate Heat Pump on ULO
Heat pump replaces both gas furnace and AC. Same envelope, same household. Switch to ULO with pre-conditioning strategy.
Annual electricity:
| Category | Quantity | Effective Cost |
|---|---|---|
| Heat pump heating | ~7,800 kWh | mostly off-peak |
| Heat pump cooling | ~1,200 kWh | mostly off-peak/mid-peak |
| Baseline electric | 6,500 kWh | mixed |
| Total electricity | 15,500 kWh | — |
Blended effective rate under ULO with pre-conditioning: 5.5-7.5 cents/kWh.
| Category | Annual |
|---|---|
| Heat pump (heating + cooling) electricity | $585 |
| Baseline electric | $580 |
| Electric delivery + regulatory | $620 |
| Electric standing charge | $300 |
| Gas eliminated (no service) | -$240 (savings) |
| Total annual | $1,845 |
Monthly average: $154.
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Get Free Estimate →Month-by-Month Profile
Approximate monthly bill profile for the reference home post-conversion (electric only; gas eliminated):
| Month | Heat Pump kWh | Bill (ULO with pre-cond) |
|---|---|---|
| Jan | 1,400 | $245 |
| Feb | 1,250 | $225 |
| Mar | 850 | $175 |
| Apr | 350 | $120 |
| May | 200 | $105 |
| Jun | 300 | $115 |
| Jul | 450 | $135 |
| Aug | 400 | $130 |
| Sep | 200 | $105 |
| Oct | 350 | $120 |
| Nov | 750 | $165 |
| Dec | 1,150 | $210 |
| Total | 9,000 | $1,850 |
Plus baseline 6,500 kWh, included in the costs above.
What Pre-Conditioning Means
ULO's massive 28.4 cents/kWh on-peak rate (4-9pm weekdays) is brutal if you run the heat pump straight through. Pre-conditioning means using the smart thermostat to:
- 4am-7am: ramp setpoint up 1-2C above target (overnight rates 2.4 cents/kWh).
- 7am-4pm: hold target setpoint (mid-peak 9.5 cents/kWh — manageable).
- 4pm-9pm weekday: hold setpoint, accept mild drift down 1-2C (avoid full-power compressor run).
- 9pm-11pm: recover to target (mid-peak).
- 11pm-7am: maintain target (overnight rates).
A well-insulated home with thermal mass (concrete basement, hardwood floors, plaster walls) can coast through the on-peak window with minimal compressor run. A poorly insulated home loses temperature too fast.
ecobee Premium, Daikin One+, and Honeywell T10 all support ULO scheduling. ecobee has the cleanest implementation for non-native heat pumps.
Sensitivity to Pre-Conditioning Discipline
Same household, different pre-conditioning discipline:
| Strategy | Annual Heat Pump kWh | Annual Bill Total |
|---|---|---|
| Pre-conditioned, ULO | 9,000 | $1,845 |
| No pre-conditioning, ULO | 9,000 | $2,250 |
| TOU, no pre-conditioning | 9,000 | $2,170 |
| Tiered (high consumption) | 9,000 | $2,380 |
Pre-conditioning saves $300-$500/year vs no strategy. The setup is one-time at thermostat install.
Sensitivity to Cold Snaps
A 10-day cold snap at -22C average drives heat pump consumption higher. Approximate impact:
- Normal January: 1,400 kWh, $245 bill.
- Cold January with 10-day snap at -22C: 1,800 kWh, $310 bill.
Roughly +$60-$80 in a cold-snap month. Annualized impact: minor.
Sensitivity to Envelope
Same heat pump, different envelope:
| Envelope | Annual Heat Pump kWh | Annual Bill Total |
|---|---|---|
| R-60 attic, R-22 walls, tight (1.5 ACH50) | 6,500 | $1,500 |
| R-30 attic, R-12 walls, average (3.5 ACH50) | 9,000 | $1,845 |
| R-12 attic, R-7 walls, leaky (6.0 ACH50) | 12,500 | $2,400 |
Envelope tightening + heat pump together is the deep-retrofit bundle that makes the math work.
Sensitivity to Hot Water and EV
Heat pump household with electric water heater:
- Add ~3,500 kWh/year for hot water.
- Bill increase ~$280/year if scheduled to overnight.
Heat pump household with EV (40 km/day commute):
- Add ~4,500 kWh/year for EV charging.
- Bill increase ~$120-$200/year if charged overnight (huge ULO benefit).
A household electrifying everything (heat pump + EV + induction range + heat pump water heater) on ULO with discipline can hold total electricity cost under $3,000/year for combined heating + cooling + transportation + cooking.
Common Surprises
Households moving from gas+AC to heat pump on ULO typically experience:
- 1. First January looks scary. Bill jumps to $250+ (no equivalent gas bill exists for comparison).
- 2. Annual total is lower or comparable. The math works on a 12-month basis, not a single month.
- 3. Cooling is cheaper than expected. Heat pump cooling is more efficient than the old AC.
- 4. Shoulder seasons are very cheap. April-May and September-October are <$120/month.
- 5. Pre-conditioning becomes habitual. After the first year, the smart thermostat learns and the homeowner stops thinking about it.
Bill-Minimization Checklist
If your goal is to minimize the post-heat-pump electricity bill in Toronto:
- Switch to ULO rate plan (free; via Toronto Hydro online portal).
- Install ecobee Premium or Daikin One+ thermostat.
- Configure pre-conditioning schedule (4-7am ramp, 4-9pm coast).
- Verify envelope: R-50+ attic, blower-door <3.5 ACH50.
- Add EV charger and shift charging to overnight (synergistic with heat pump).
- Switch water heater to heat pump water heater on overnight schedule.
- Consider battery storage if solar PV is added later (Greener Homes Loan eligible).
When ULO Is Not Right
ULO is wrong if:
- Household is home all day with constant heating demand (cannot exploit overnight pricing).
- Envelope is leaky (cannot coast through peak window).
- Smart thermostat is not installed or not configured.
- HVAC is short-cycling (cannot pre-condition effectively).
In those cases, TOU is typically the better default.
Next Steps
If you are evaluating heat pump conversion in Toronto and want a custom bill projection for your specific home, we run a 12-month simulation using your actual gas and hydro consumption history. Bring your last year of bills to the scoping visit.
Book at /services/hvac-energy/heat-pump-conversion. For full conversion guide, see Heat Pump Conversion Toronto: The Complete 2026 Guide. For the gas vs heat pump comparison, see Heat Pump vs Gas Furnace Toronto Comparison.
Sources & References
Authoritative sources cited in this guide:
- NRCan — Heating and Cooling — NRCan heating/cooling guidance
- Canada Greener Homes Loan — Federal energy retrofit financing
- CSA F326 (Mechanical Ventilation) — Residential HRV/ERV standard
- Enbridge Home Renovation Savings (HRS) program — Provincial heat pump rebate
- TSSA Fuel Safety — Ontario fuel/gas regulator
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