There are a lot of windows in our house, including covering almost all the northern walls. We have large overhangs (600mm) from the roof on all sides to shade the windows in summer but let light in the northern windows in winter. All three southern windows are small and high. We do however, have three large eastern windows (one deep in the veranda) and one large western window that may cause heat issues in summer. We plan to plant decidous trees/vines to shade these eastern and western windows in summer, whilst allowing winter sun, but this will take some years to come into effect.

View from the north east corner

The Your Home Technical Manual on Glazing says:

"Glazing has a major impact on the energy efficiency of the building envelope. Poorly designed windows, skylights and glazed surfaces can make your home too hot or too cold. If designed correctly, they’ll help maintain year-round comfort, reducing or eliminating the need for artificial heating and cooling.

Windows in a typical insulated home can account for more heat gain or loss than any other element in the building fabric. In summer heat gain through an unshaded window can be 100 times greater than through the same area of insulated wall. One square metre of ordinary glass can let in as much heat as would be produced by a single bar radiator. In winter, heat lost through a window can be ten times more than through the same area of insulated wall."

Unfortunately our budget did not allow us to get the best possible windows - we have single glazing, untinted glass on aluminium frames (the frames are white, which does help with reflecting heat a little). At some stage I would like to get tinting to reduce the UV wear on internal furnishings. We will have to rely on good blinds/curtains/external shades to help regulate our temperature. At this stage I am most worried about letting the cold in on winter nights. We haven't yet decided on window furnishings (it will depend on our budget at the end of the build) so if anyone has good suggestions, feel free to post them here in the comments field.

Our celestory windows should provide a very good temperature balance in our house. In winter they will allow the midday sun to hit our rammed earth wall and store the heat, releasing into the night. Although our ceilings at that point are around 4.5m high, we do have a ceiling fan on one half of that area which we will reverse to circulate warm air that has risen back around the room. In summer they will be shaded and can open to allow heat to move upwards using the stack effect principle.

Celestory windows

Sun hitting earth wall at 8.30am in May

As a side note, all rooms in our house (excluding bathrooms and laundry) have light/windows on at least two sides - following Christopher Alexander's Pattern Language.

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