Passive House Standards for Canadian Residential Projects

Two Certification Bodies, Two Different Performance Targets

In Canada, residential builders working toward passive house certification encounter two primary standards: the Passive House Institute (PHI) originating in Germany, and the Passive House Institute US (PHIUS), which developed the PHIUS+ standard beginning in 2015. The core difference between them lies in how heating and cooling load limits are set.

PHI applies a single set of limits across all climate zones — a maximum specific heating demand of 15 kWh/m²/year and a maximum peak heating load of 10 W/m². PHIUS takes a different approach: its limits are climate-specific, calculated using the passive building analysis tool (WUFI Passive) to derive targets that reflect the actual weather data at a project's location. For Canadian projects in Climate Zone 6 or colder, the PHIUS annual source energy limits are often more demanding than PHI's flat thresholds, particularly when accounting for heating-dominated conditions over long winters.

Neither approach is objectively superior for all Canadian sites. PHI's simpler framework suits projects where the design team is already accustomed to European energy modelling conventions. PHIUS's climate-specific targets are calibrated more precisely to North American construction practice and to the variable conditions across a country spanning multiple climate zones.

Airtightness: The Non-Negotiable Baseline

Both PHI and PHIUS require a measured airtightness of 0.6 ACH50 or better — meaning that when the building is depressurized to 50 Pascals, the air change rate must not exceed 0.6 times the building volume per hour. This result is verified through a blower door test conducted by a certified technician before occupancy.

Achieving 0.6 ACH50 in a Canadian cold-climate project typically requires:

• A continuous air barrier layer, either interior polyethylene, membrane-based systems, or airtight sheathing with taped joints
• Special attention to penetrations through the air barrier plane — including electrical boxes, service entries, and structural connections
• Pre-drywall blower door testing to identify and correct leaks before finishes close off access
• Coordination between trades to prevent trades installing after the air barrier is complete from creating new penetrations

In practice, builders aiming for 0.6 ACH50 from the outset often achieve results in the 0.3–0.5 range, because the standard forces systematic attention to details that most conventional construction treats as secondary.

Mechanical Ventilation with Heat Recovery

A building envelope tight enough to meet passive house airtightness requirements cannot rely on infiltration for fresh air supply. A dedicated mechanical ventilation system with heat recovery (HRV or ERV) becomes mandatory — not merely advisable.

HRV units suitable for Canadian cold-climate passive house applications need to maintain heat recovery efficiency above 75% at outdoor temperatures as low as -25°C. Several manufacturers offer units rated to this range, though the defrost strategy — whether electric resistance preheat, a glycol coil loop, or a recirculation cycle — affects both energy use and the unit's ability to maintain continuous ventilation during cold snaps.

ERVs, which also transfer moisture in addition to heat, are sometimes preferred in mixed-humid climates such as southern British Columbia, where indoor humidity control in summer months is a concern. In colder, drier Prairie climates, HRVs are more common because ERVs can transfer outdoor moisture inward during winter, raising indoor relative humidity above comfortable levels when occupant loads are high.

Window Performance Requirements

Windows represent the weakest point in most passive house envelopes. PHI's certification database lists windows by their frame and glazing assembly U-values; the threshold for Canadian climates is typically a total window U-value of 0.8 W/m²K or lower when tested to the ISO 10077 standard. This corresponds roughly to a triple-glazed unit with two low-emissivity coatings and an argon or krypton fill.

PHIUS uses NFRC ratings in Imperial units. A window meeting PHIUS requirements for Climate Zone 6 generally has a total NFRC U-factor of approximately 0.14 BTU/hr·ft²·°F or below (equivalent to about 0.79 W/m²K), along with a solar heat gain coefficient (SHGC) calibrated to the solar radiation profile at the project location.

South-facing glazing in Canada has meaningful solar gain potential between November and February, particularly at latitudes between 45° and 55° N. Passive house energy modelling software — PHPP for PHI projects, WUFI Passive for PHIUS — accounts for this orientation-specific gain, which means south-facing window area can contribute positively to the heating demand calculation when external shading is controlled properly.

Thermal Bridge-Free Construction

Thermal bridging — the conduction of heat through structural elements that penetrate the insulation layer — accounts for a disproportionate share of heat loss in conventional construction. Passive house certification requires that thermal bridges be quantified and either eliminated or reduced to a linear thermal transmittance (psi-value) below 0.01 W/mK.

Common thermal bridge locations in Canadian residential construction include:

• Cantilevered balcony slabs continuous with the interior floor structure
• Window and door frames bearing on the structural framing rather than the insulation layer
• Structural steel or concrete posts penetrating the building envelope
• Foundation-to-wall transitions at the slab edge
• Fasteners for exterior cladding systems — particularly long screws through continuous insulation to the structural sheathing

Thermal bridging through cladding fasteners in exterior insulation assemblies has received increasing attention from Canadian building researchers. The difference in effective R-value between a continuous mineral wool assembly and one penetrated by conventional stainless steel screws at standard spacing can be equivalent to losing an entire inch of insulation.

Certification Process in Canada

PHI certification is pursued through the PHI database and verified by an accredited passive house certifier. A list of certifiers active in Canada is maintained by Passive House Canada. The design must be modelled in PHPP (Passive House Planning Package), and a final certification audit is submitted with blower door test results, thermal bridge calculations, and equipment documentation.

PHIUS certification involves registration with PHIUS early in the design process, energy modelling using WUFI Passive, and a third-party verification process managed by a PHIUS-certified rater. The PHIUS Quality Assurance program includes both a pre-construction design review and post-construction verification, making it more prescriptive in process than PHI certification.