Whatever your type of building, whether it’s passive solar or not, good insulation is fundamental.
Insulation is one of the most cost-effective ways of reducing the environmental footprint and running costs of a building. Even so, as you can see from this map, the standard of home insulation in many European countries is still quite poor.
A sufficiently well-insulated building can stay comfortable with no heating system, even without capturing solar energy. However, for this to work, all parts of the building, including the windows, need to be highly insulated, also mechanical ventilation with heat recovery may be required. The Passivehouse standard has been developed to certify these highly insulated buildings.
This doesn’t just apply to houses: the world’s tallest Passivhaus building is a 32-storey skyscraper in Bilbao, Basque Country, Spain, completed in 2018.
In passive solar buildings, insulation needs to be combined with thermal mass. Thermal mass is the capacity of a material to store heat like a battery. This helps to even out temperatures between day and night, cloudy and sunny days. Materials like earth, masonry, concrete, and water have high thermal mass.
In order to work effectively, thermal mass needs to be located on the inside of the insulation envelope, and ideally in direct sun. For example, the insulated floor slab and earth plastered interior walls of this straw bale house built by the creators of Abrazo House.