Ontario Housing & Heating Scenario (2021–2030) – Heat Pumps & Hydronic Balancing
This page summarizes the Ontario housing stock, the split between houses and condos, the dominant heating fuels,
and a 2030 scenario where part of the gas-heated stock and a share of new homes switch to heat pumps with proper
hydronic balancing. All numbers are rounded and intended as engineering-level estimates, not official statistics.
1. Ontario Housing Stock by Building Type (2021)
According to the 2021 Census, Ontario has about 5.49 million occupied private dwellings.
Roughly half of these are single-detached houses, and close to one million are high-rise apartment or condo units.
| Building type | Share of dwellings | Approx. number of dwellings |
|---|---|---|
| Single-detached houses | 53.6 % | ≈ 2.94 million |
| High-rise apartments / condos (5+ storeys) | 17.9 % | ≈ 0.98 million |
| Other (semi-detached, row, low-rise apartments) | 28.5 % | ≈ 1.57 million |
| Total occupied dwellings | 100 % | ≈ 5.49 million |
2. Heating Mix by Dwelling Type – Houses vs. Condos
Province-wide energy statistics indicate that around 72 % of residential space-heating energy in Ontario
still comes from natural gas, with most of the remainder from electricity and a small tail of other fuels. Detached houses
are more gas-dependent, while condos have a higher share of electric and heat pump heating. The table below shows a stylized
breakdown consistent with provincial data and surveys.
| Dwelling type | Main heating fuel | Approx. share of stock | Approx. number of dwellings |
|---|---|---|---|
|
Single-detached houses ≈ 2.94 million |
Natural gas | ≈ 84 % | ≈ 2.47 million |
| Electric / heat pump | ≈ 13 % | ≈ 0.38 million | |
| Other (oil, propane, wood) | ≈ 3 % | ≈ 0.09 million | |
|
High-rise condos / apartments ≈ 0.98 million |
Natural gas (central boiler) | ≈ 47 % | ≈ 0.46 million |
| Electric / heat pump | ≈ 42 % | ≈ 0.41 million | |
| Other | ≈ 11 % | ≈ 0.11 million |
Approximate Residential Heating Mix in Ontario
Stylized bar chart based on provincial energy data – natural gas still dominates residential space heating.
72 %
23 %
5 %
3. 2030 Scenario – Existing Stock + New Construction
To make the projections more realistic, we combine two effects:
(1) a share of today’s gas-heated homes switching to heat pumps with balanced hydronic systems, and
(2) a growing fraction of new homes being built with electric or heat-pump heating instead of gas.
Numbers below are stylized engineering estimates for Ontario, not official forecasts.
Existing gas-heated homes
- Gas-heated homes today: ≈ 2.93 million
- Share converted by 2030: 20 %
- Homes converted to HP + balancing: ≈ 586,000
- Indicative gas use: ≈ 2,100 m³/home/year
- Resulting CO₂ reduction: ≈ 1.5 Mt CO₂/year
- Energy-bill savings: ≈ 245 M CAD/year
New homes 2025–2030
- Illustrative new homes built 2025–2030: ≈ 720,000
- Baseline: majority gas-heated
- Heat-pump policy case: much higher HP/electric share
- Additional HP homes vs. gas baseline: ≈ 210,000–220,000
- CO₂ reduction from these new builds: ≈ 0.5–0.6 Mt CO₂/year
- Energy-bill savings: ≈ 80–90 M CAD/year
Combined 2030 impact
- Total CO₂ reduction: ≈ 2.0 Mt CO₂/year
- Equivalent to ≈ 450,000–500,000 cars off the road
- Total energy-bill savings: ≈ 330 M CAD/year
- Requires both:
- Deep retrofits of existing buildings
- High heat-pump adoption in new housing supply
- Hydronic balancing (PICVs + automatic balancing valves) is a key enabler for stable COP and delta-T.
4. Where Does Heat Go in Unbalanced Systems?
In unbalanced hydronic systems, a significant portion of pump flow short-circuits through the lowest-resistance branches.
This leads to low ΔT, higher return temperatures and reduced heat-pump COP. Proper use of
automatic balancing valves and pressure-independent control valves (PICVs) keeps flows proportional,
protects ΔT and reduces wasted pumping energy.
- Unbalanced system: over-supplied branches, under-supplied terminal units, frequent cycling, low ΔT.
- Balanced system: stable flows per loop, design ΔT, lower return temperature, higher seasonal COP.
- For heat pumps: every few degrees of lower return temperature can make a noticeable difference in COP and annual kWh.
5. Notes & Assumptions
All numbers above are approximate and intended for illustrative engineering scenarios in Ontario.
Housing counts are based on Statistics Canada 2021 Census dwelling data; fuel shares are aligned with provincial energy
reports and scaled down to dwelling counts. The 2030 conversion and savings scenario is not an official forecast, but a
stylized case to highlight the potential role of heat pumps and hydronic balancing in decarbonizing residential heating.
