The major goal of the Biosolar house was to provide a delightful living environment; one that requires minimal energy input to maintain a wonderfully comfortable temperature, regardless of outside conditions.

It achieves this goal by essentially being “a house within a house”; the sealed double-cavity of the exterior walls can draw heated air from the greenhouse-style attic on cold days, or be ventilated on warm days to draw hot air away.

The following gives more details on the features.

Absorber attic

Almost 60% of the roof is covered with 16mm thick acrylic glass, so the space between roof and ceiling works as a greenhouse- even a little sunshine will warm the absorber attic considerably.

This warmed air flows into the sealed double cavity on the outside of the walls and helps to keep the house warm in winter.

The ceiling between the absorber and the living rooms below is incredibly well insulated to avoid overheating.

The attic also has a ventilation system, so on warm days the hot air will be guided away from the cavity.


The foundation of the house is a standard concrete pad. After erecting the house the pad is sealed with a vapour barrier and then a 160mm layer of wool insulation and a joist system is installed to allow a wooden floor/tile or parquet finish.

The standard wall insulation thickness is 200mm, while the ceiling (as a barrier to absorber room) is insulated with up to 350mm thickness of wool.


The windows for this project are manufactured in Germany, using double or triple glazing (depending on their situation). They feature a sophisticated ventilation system and can fully open inwards.

The windows are also draught-proof and fitted with exterior shutters to keep out wind, light, or storm conditions.

All services like electricity, heating and plumbing are run in an installation cavity inside the wall so that there is no need to cut or drill the vapour- and draft-proof building core.

Wall and ceiling heating

Over 800 meters of heating pipe is installed in the installation cavity and the ceiling for central heating.

The hot water for the system is stored in a big 1000 litre boiler powered by a wet back and solar panels, with electricity as a backup.


Any sort of cladding can work with a Biosolar house.

This project features an oiled cedar cladding fixed with stainless steel screws.

The Biosolar project shows it’s possible to build an affordable, sustainable house that’s a joy to inhabit and requires minimal energy to keep at a cosy temperature.

To find out more, or to build your dream home…