How To Build A Passive House

Want to reach the gold standard for energy efficiency for your self-build? Find out what you need to achieve Passivhaus status.

By Sarah Warwick

What Is Passivhaus?

Passivhaus is a standard for building construction, including homes - it's a German standard, hence Passivhaus. The house is built to be extremely energy efficient, and has a comfortable interior climate maintained without a traditional heating system - or active cooling.

The passive house uses the sun, its occupants, household appliances and the extracted air - passive heat sources - to cover much of the heat demand. The remaining heat is provided by the supplied air, and is sufficient as a heat source because the house has such reduced heat losses.

To do this, a passive house is built with high levels of insulation; exceptional air tightness; uses passive solar gains - windows, walls and floors collect, store and distribute solar energy in winter and reject it in summer - as well as the internal heat sources; has energy-efficient glazing and frames; and has whole house mechanical ventilation with heat recovery for good indoor air quality. It should also have low energy appliances and lights.

The reduced energy demand of a passive house can be provided by renewable sources, such as solar panels and heat pumps.

You can open the windows of a passive house - although you shouldn't need to as the ventilation system provides fresh air.

Why Build A Passive House?

A passive house will save you money on heating bills. A 75% reduction in space heating requirements compared to standard UK new build is achieved, according to the Passivhaus Trust. Be aware that building it will cost more in the first place - estimated at between 3 and 8% by the International Passive House Association.

Along with saving on bills, you will also be reducing carbon dioxide emissions and preserving fossil fuels.

A passive house won't have draughts and will be evenly warm with a constant climate. If you have allergies, you'll benefit from the filters that keep pollen and dust out of the house.

The Passivhaus Standard

For PassivHaus certification, these are the energy performance targets your home must meet:

Specific heating demand: less than or equal to 15kWh/m²/year
Specific heating load: less than or equal to 10W/m²
Specific primary energy demand: less than or equal to 120kWh/m²/year

The primary energy demand target must include: space heating, domestic hot water, lighting, fans, pumps, and all projected appliance consumption. This target must be met along with either the specific heating demand or the specific heating load.

How Do You Meet The Standard?

If you want to build a passive house, you need to begin with the right site, and find out whether planning permission for your proposed design is likely. It will need to be designed bearing in mind building shape, the need for large south-facing windows, the routing of ventilation ducts, and much more. You can find a checklist at the Passive House Institut .

The Passivhaus planning package (PHPP) is used in the design process. This allows the architect or designer to assess the energy performance of the house based on the design, ventilation, climate and so on. Certified designers and consultants in the UK can be found on the Passivhaus website.

To gain certification, you will need to apply for a quality assured Passive house certificate from the The Passivhaus Institut or through the BRE website, the Scottish Passive House Centre or Warm.