The term ‘Passive House’ (PH) comes from the German, Passivhaus and is a building standard that recognises ultra-low energy buildings that do not require a lot of energy for heating and cooling. Although the popularity of the PH is spreading, currently the largest concentrations of these buildings are in German-Speaking countries.
What is a Passive House?
This type of house uses the heat generated by the sun, the occupants of the house, electric appliances and extracted air to heat and cool the house. They can be maintained at a comfortable temperature without a traditional heating system. They use no more than 1.5 litres of heating oil per square metre over a whole year. This means the cost of heating a house of this type with oil is about £1.68 per square metre per year in the UK.
How do they work?
They are very energy efficient. They are almost 100% air tight, preventing energy exchange with the outside air. They are also usually built with large south-facing windows, and trapped solar energy can heat the house for a long period of time. They are super-insulated and use triple-plane double-glazing to retain warmth.
Advantages of a passive house
The Passivhaus Trust estimates that there is a 75% reduction in heating demands when compared to a UK New Build. As New Build houses must meet high insulation targets, this means that a passive house will benefit from hugely reduced energy bills during the year. Low-energy air filters installed in a passive house also remove all pollen and dust from the inside of the house, making them suitable for people with allergies. These benefits are coupled with a huge reduction in carbon emissions and preserving fossil fuels.
Can you convert to a passive house?
PH certification is available for retro-fits as well as new builds. The targets to meet for retro-fit houses are slightly more lenient for retro-fits. For example a passive house requires that the total energy requirement over the whole year is no more than 120kWh per metre squared. This includes the heating of the house. A retro-fit passive house meets the standard if it’s energy usage is less than 120kWh per metre squared plus an extra heating allowance of 25kWh per metre squared.
Heating a house this way is far cheaper than a regular house, no matter where you live. These type of homes have been built in the Arctic, and function there just as effectively as they will in the UK. Heating costs are so low that an entire house can be heated for a whole year with one pack of bioethanol gel fuel.