Passivhaus Criteria Calculator

Passivhaus is the world's leading standard for energy-efficient buildings, originating in Germany. It reduces heating demand by up to 90% compared to typical buildings through super-insulation, airtightness, thermal bridge-free design, high-performance windows, and mechanical ventilation with heat recovery (MVHR).

Space heating: annual demand max 15 kWh/m².a OR peak heating load max 10 W/m² — these are alternatives, so only ONE need be met (Passivhaus Trust criteria v10c, footnote 3). Space cooling demand: max 15 kWh/m².a (where active cooling is fitted). Primary Energy Renewable (PER): max 60 kWh/m².a for Classic, 45 for Plus, 30 for Premium. Airtightness: max 0.6 air changes per hour at 50Pa (n50). The space-heating, cooling, PER and airtightness criteria must all be satisfied for certification.

Classic requires PER up to 60 kWh/m².a with no on-site generation requirement. Plus requires PER up to 45 kWh/m².a plus renewable generation of at least 60 kWh/m².a, and Premium requires PER up to 30 kWh/m².a plus generation of at least 120 kWh/m².a. Crucially, the generation thresholds are measured per square metre of PROJECTED BUILDING FOOTPRINT (the ground area the building covers), not per square metre of treated floor area, while the PER demand limits are measured per square metre of treated floor area.

Airtightness is tested using a blower door test (pressure test) at 50 Pascals. The Passivhaus limit is 0.6 ACH@50Pa (air changes per hour at 50 Pascals). This is extremely airtight - typical UK new builds achieve 3-5 ACH@50Pa. Achieving 0.6 requires careful detailing and quality workmanship.

Passivhaus buildings need very little heating - the post-heating air from the MVHR system can often provide enough warmth. A small backup heater (electric panel or heat pump) may be needed for the coldest days. Radiator systems are usually unnecessary.

A Passivhaus typically costs 8-15% more than a standard build. Costs are reducing as the approach becomes mainstream. The premium is offset by dramatically lower energy bills (up to 90% reduction in heating costs), improved comfort, and higher property values.