PassivHausPassivHaus is a low energy building standard developed by Dr Wolfgang Feist. By carefully designing the building in accordance with set principles (technical and design based principles), the resultant building should require minimial heating or cooling energy during it's use.

Principles include:

  • Compact form and good solar orientation.

  • Use of mechanical ventilation to provide fresh air to the occupants whilst retaining as much internal heat through a heat exchange unit. This is called a Mechanical Heat Recovery unit (MVHR)).

  • Annual heat requirement ≤ 15kWh/m2.a OR 10W/m2

  • Annual energy requirement ≤ 120kWh/m2.a

  • U-values of opaque elements ≤ 0.15W/m2.K

  • U-values of glazed elements ≤ 0.8W/m2.K

  • Air-tightness ≤ 0.6 air changes/hour

  • MVHR min 80% efficient, ≤ 0.45W/m3

  • Thermal bridging values ≤ 0.01

  • ≤ 10% overheating

  • PassivHaus is reliant on the design team and contractor. Great care is therefore required for excellent detailing, and care that the contractor can deliver the building to the required standard.

Fox Ecological Architects have experience of designing a PassivHaus in the Scottish Boarders. Whilst we are not PassivHaus designer's, we can offer advice and support to pursue this standard should it be desired.

Word of caution:
It's worth pointing out that there is no guidance on material selection for PassivHaus. This can lead to an issue where polluting (off-gassing) materials can accumulate more readily in an air-tight space (even with good quality MVHR) such as a PassivHaus. Consequently, we advise that those aiming for PassivHaus also strongly consider material selection carefully to avoid a poor internal air quality. We can assist in the selection of low toxic materials, so that your PassivHaus can not only save on energy use, but also deliver a healthy indoor environment. See section on low pollutant materials.

Plummerswood PassivHaus. Copyright Gaia Architects. A project that Matthew was an architect on, whilst working at Gaia Architects.

Passivhaus projects can look like typical homes too. Ford Farm, Cornwall. Warm Associates.