Real bills and temperature logs from a Passive House multi-unit building in Peterborough and a single-family Passive House on Wolfe Island confirm excellent thermal stability and big heating savings in this 2025 study.
Where energy and emissions diverge most is in hot water and fuel choice—and where comfort can vary is shading and operations.
Why this matters
We often lean on modeled performance to make Passive House decisions. This study did the harder thing: it compared PHPP/HOT2000 simulations with actual utility bills and indoor temperature logs after move-in. The result is a clear picture of how envelope, systems, shading, and occupancy interact once people are living in the building.
The projects at a glance
- Peterborough MURB (12 units, wood-frame, gas boiler for space heat/DHW, Zehnder HRVs).
Achieved excellent airtightness (0.36 ACH50) and high-performance windows. AC was added after initial summer discomfort. - Wolfe Island House (single-family, CLT shell, all-electric with 2 kW supply-air heater + ERV, electric DHW).
Very tight (0.48 ACH50) with certified Passive House windows; entirely grid-electric.
Peterborough MURB
Wolfe Island House
Do the models match reality?
Yes—within practical margins.
- Peterborough: Modeled electricity tracked bills closely outside move-in ramp-up; winter months were 0.6–0.8 MWh higher than simulation, likely reflecting occupant behavior and plug loads.
- Wolfe Island: PHPP aligned best in mid-winter; HOT2000 over/under-shot shoulder seasons. Deviations peaked around 25–28% in some months.
Takeaway: PHPP/HOT2000 are reliable enough for design and policy decisions, but shoulder-season behavior and occupancy patterns still drive variance.
Comfort: did the homes stay within the Passive House overheating criterion?
Mostly, yes—and the data loggers show why.
- Criterion: ≤10% of annual hours above 25 °C.
- Peterborough: Monthly average indoor temps by unit ranged ~22.8–26.3 °C. Warmest exposures were SE/NE on lower floors; the NE third-floor unit ran coolest in winter (roof exposure + low solar gains).
- Wolfe Island: With the thermostat set to 20 °C, monthly averages were ~18.1–19.4 °C; owners occasionally used a small portable heater in the mornings. A holiday absence dipped to 13 °C, illustrating slow temperature drift thanks to the high-R, high-mass envelope.
Takeaway: Comfort targets were met when occupied. Exposure, shading, and occupancy schedules matter more than we think—even in certified envelopes.
Energy: where the savings (really) show up
Space conditioning
- Peterborough: –99% heating, –14% cooling vs. OBC 2017; combined –82% for heating+cooling.
- Wolfe Island: –96% heating, –8% cooling; combined –90% for heating+cooling.
Shading reduced cooling energy materially in both buildings; removing overhangs increased summer loads.
Whole-building energy
- Peterborough: Only –18% total vs. code, despite dramatic heating savings. Why? Natural gas DHW and higher baseloads/occupancy per m² kept totals elevated.
- Wolfe Island: –39% total vs. code, driven by an all-electric system that translates envelope performance directly into site energy reduction.
What leaked the most (before Passive House improvements)?
Both buildings saw the largest heat-loss reduction from airtightness (≈86–87% reduction in infiltration loads), followed by walls, roof/ceiling, and slab.
Emissions: fuel choice is decisive
- Peterborough: –8% GHG vs. code. Space heat fell sharply, but gas DHW limited gains.
- Wolfe Island: –39% GHG, essentially mirroring total energy cuts because it’s 100% electric (and benefits from a relatively clean Ontario grid).
Takeaway: To unlock Passive House’s full climate value, move domestic hot water and space conditioning to high-efficiency electric (heat pumps) and consider drain-water heat recovery.
Operations & design lessons from real life
- Validate shading early—and keep it.
Overhangs and operable shading are not optional in mixed heating/cooling climates. Removing them or undersizing them raises cooling energy and summer discomfort risk. - Right-size and right-place cooling.
The MURB required supplemental AC after move-in. For multi-unit buildings, decentralized, efficient heads or a small, centralized heat-pump system can keep peaks low without compromising envelopes. - Prioritize airtightness; it pays back first.
The single biggest modeled-to-measured gain came from infiltration control. Invest in detailing, QA/QC, and multiple blower-door tests. - Plan for domestic hot water decarbonization.
Gas DHW can erase a big slice of the climate benefit. Heat-pump water heaters, DWHR, and recirculation controls should be standard Passive House companions. - Expect occupancy to nudge results.
More people per m² (MURB) means higher internal gains and plug loads. Metering and feedback help residents understand how their habits shape comfort and bills. - Use both PHPP and measured data to tune.
PHPP/HOT2000 gave good direction; monthly bill checks and low-cost temp logging verified performance and highlighted edge cases (exposure, top-floor effects).
What this means for Canadian Passive House projects
- Single-family, all-electric Passive Houses will typically show larger % reductions in both energy and GHGs compared with code than gas-served multi-unit buildings—even when envelopes are equally strong.
- Multi-unit Passive House still slashes heating energy, but whole-building totals and emissions hinge on DHW strategy and end-use electrification.
- Post-occupancy monitoring—utility bills + strategic data logging—should be treated as part of the project scope, not a nice-to-have. It closes the loop between design intent and lived experience.
Quick spec checklist (from the winners in the data)
- ≤ 0.6 ACH50 (both projects beat it).
- High-performance triple glazing with tuned SHGC by orientation.
- External shading sized for latitude and façade.
- Balanced HRV/ERV (Zehnder units with ~92% heat recovery were used).
- Electrified space heat & DHW where feasible; add DWHR.
- Comfort sensors (temp/CO₂) + utility bill review in Year 1.
Source: Mach, A.; Parra, M.; Teamah, H. Post-Occupancy Evaluation of a Passive Multi-Unit Residential Building and a Single-Family Passive House. Sustainability 2025, 17, 3799. https://doi.org/10.3390/su17093799
Data summarized with emphasis on measured energy use and indoor temperatures.
