Glazing

The amount of glazing and its position has a dramatic effect on energy use and comfort:

• Glass is thermally inefficient. Triple glazed units or low ‘e’ glass are six times more efficient than double glazed units.

• Windows placed in a south facing elevation will provide better lighting and some solar gain but care should be taken in the amount of glazing to avoid overheating. Windows with solar reflective film will help.

• Limit the area. Keep this to about 25% of the floor area plus the area of the original glazing covered over by the extension.

• Timber frames offer the best solution. PVC frames are low maintenance but difficult to repair/dispose/recycle.