What Is a Passive House?
A Passive House (Passivhaus in German) is a rigorous building standard focused on achieving ultra-low energy consumption for heating and cooling. Developed by the Passivhaus Institut in Darmstadt, Germany, in 1988, the standard requires buildings to use no more than 15 kWh/m²/year for heating or cooling, which represents a 75-90% reduction compared to typical new construction.
Passive houses achieve this through five key principles: superinsulation with continuous insulation envelopes, airtight construction with minimal thermal bridging, high-performance windows (triple-glazed, low-e), mechanical ventilation with heat recovery (MVHR) at 75%+ efficiency, and passive solar design with strategic orientation and shading.
Energy Savings Calculation
Passive House Requirements
| Criteria | Passive House Standard | Typical Building |
|---|---|---|
| Heating Demand | ≤ 15 kWh/m²/yr | 60-200 kWh/m²/yr |
| Primary Energy | ≤ 120 kWh/m²/yr | 200-400 kWh/m²/yr |
| Airtightness (n50) | ≤ 0.6 ACH | 3-10 ACH |
| U-value Walls | 0.10-0.15 W/m²K | 0.25-0.50 W/m²K |
| Window U-value | ≤ 0.80 W/m²K | 1.2-2.5 W/m²K |
Frequently Asked Questions
How much more does a passive house cost?
A passive house typically costs 5-15% more to build than a conventional home, depending on location and design. However, the energy savings often pay back the extra investment within 7-15 years, after which the homeowner enjoys significantly lower utility bills for the life of the building.
Do passive houses work in hot climates?
Yes. While originally developed for cold climates, the Passivhaus Institut has adapted the standard for all climate zones. In hot climates, the focus shifts to cooling demand, with strategies including shading, reflective surfaces, nighttime ventilation, and dehumidification integrated into the MVHR system.
Can existing buildings be retrofitted to passive house standards?
The EnerPHit standard provides a slightly relaxed certification for retrofits, allowing up to 25 kWh/m²/year heating demand. Deep energy retrofits typically involve adding external insulation, replacing windows, sealing the building envelope, and installing an MVHR system, achieving 60-80% energy reductions.