Inhaltsverzeichnis
- Metric PHI limit Sensible heat recovery efficiency (HRV/ERV) ≥ 75% (most certified units exceed 80–90%) Specific fan power ≤ 0.45 Wh/m³ (≤ 0.765 W/CFM) Airtightness (new build) n50 ≤ 0.6 h−1 at ±50 Pa Heating demand ≤ 15 kWh/m²/year, or peak ≤ 10 W/m² An airtight envelope makes mechanical ventilation unavoidable for IAQ, and the 75% floor means incoming air is pre-conditioned to within a few degrees of indoor temperature — fresh air with minimal energy penalty. A summer bypass lets the core be skipped in mild weather.
- The PHI retrofit pathway, EnerPHit, relaxes the envelope but keeps recovery strict: Heating demand ≤ 25 kWh/m²/year (or airtightness ≤ 1.0 ACH50). Minimum heat recovery efficiency ≥ 75% (UK climate-specific tables set 75–80% depending on zone). Triple-glazed windows (U ≤ 0.80 W/m²K) and minimal thermal bridging.
- In North America, PHIUS+ (Chicago) offers climate-specific targets (CORE, ZERO, REVIVE families) optimized for carbon and cost per climate zone, using a different energy model. Both certify buildings, designers, and components independently.
- A 75% Passive House floor is far above the ASHRAE 90.1 50% minimum and the EU Ecodesign 73% equipment threshold — though Ecodesign measures thermal efficiency (ηt) while PHI measures sensible. For critical ventilation, a non-rotating membrane core can meet the sensible floor without cross-contamination; a wheel does too but needs the frost and leakage care in wheel troubleshooting. See the enthalpy vs membrane comparison for the device trade-off.
The Passive House (Passivhaus) standard — from the Passive House Institute (PHI) in Darmstadt — is the most demanding envelope-and-services benchmark in buildings, and continuous ventilation with heat recovery is mandatory. This article covers the recovery requirements and how they compare with code minimums.
| Metric | PHI limit |
|---|---|
| Sensible heat recovery efficiency (HRV/ERV) | ≥ 75% (most certified units exceed 80–90%) |
| Specific fan power | ≤ 0.45 Wh/m³ (≤ 0.765 W/CFM) |
| Airtightness (new build) | N50 ≤ 0.6 h−1 at ±50 Pa |
| Heating demand | ≤ 15 kWh/m²/year, or peak ≤ 10 W/m² |
An airtight envelope makes mechanical ventilation unavoidable for IAQ, and the 75% floor means incoming air is pre-conditioned to within a few degrees of indoor temperature — fresh air with minimal energy penalty. A summer bypass lets the core be skipped in mild weather.
The PHI retrofit pathway, EnerPHit, relaxes the envelope but keeps recovery strict:
- Heating demand ≤ 25 kWh/m²/year (or airtightness ≤ 1.0 ACH50).
- Minimum heat recovery efficiency ≥ 75% (UK climate-specific tables set 75–80% depending on zone).
- Triple-glazed windows (U ≤ 0.80 W/m²K) and minimal thermal bridging.
In North America, PHIUS+ (Chicago) offers climate-specific targets (CORE, ZERO, REVIVE families) optimized for carbon and cost per climate zone, using a different energy model. Both certify buildings, designers, and components independently.
A 75% Passive House floor is far above the ASHRAE 90.1 50% minimum and the EU Ecodesign 73% equipment threshold — though Ecodesign measures thermal efficiency (ηt%b 0%b 7) while PHI measures sensible. For critical ventilation, a non-rotating membrane core can meet the sensible floor without cross-contamination; a wheel does too but needs the frost and leakage care in wheel troubleshooting. See the enthalpy vs membrane comparison for the device trade-off.