Free passive solar heating in your straw bale house.

Passive solar heating is the use of the changing angle of the sun with the seasons. In conjunction with the design and orientation of a building, in particular the windows and overhanging roof on the northern side, a natural solar heating system can be built into a house. The low angle of the sun in the winter months means it can shine well inside a building to warm it up. As the seasons advance the sun sweeps in a higher arc until it passes almost overhead in mid summer. With the correct amount of eave or roof-overhang, the sun will no longer shine inside in these hotter months.

How big is an eave then?

The correct eave overhang is calculated as 45% of the height under the eave to the height of the bottom of the window. So if the distance from under the eave to the window-bottom was 2 metres, the eave should extend out 90cms.

Thermal mass in a straw bale home.

Thermal mass is like a heat bank but this is also a cool bank. This is the solid material such as concrete, stone, render or brick that acts to store the ambient temperature inside the house. Remember, 20 degrees will feel warm in winter but also cool in summer.

And it all comes together..

A house with correct orientation, high insulation, quality glazing (or curtains and shuttering) and sufficient thermal mass will require a minimum of heating and cooling to be comfortable. Straw bale is an ideal building material for it's insulation, the mass of the render, it's ecological credentials and the aesthetic qualities of a professionally built straw bale home.