Improving Building Insulation
Green roofs can make a major contribution to the building insulation reducing heating or air-conditioning costs.
Research clearly highlights the value of green roofs in cooling a building in summer, but little in terms of winter insulation. This is good news as greater amounts of energy are now used for cooling buildings in summer than for warming buildings in winter.
The benefits of green roofs in summer come partly from the shading effects of the plant cover, and partly from the cooling effect of evaporation from the plant and substrate surfaces.
Reductions of up to 90% in solar energy gain on a plant-shaded roof can be achieved while indoor temperatures have been shown to be 3-4 degrees centigrade lower under a green roof when outdoor temperatures are between 25 and 30 degrees C
Measurements and modelling of green roofs have shown that green roofs can:
- Reduce summer surface roof temperatures by between 10 and 30 degrees C
- Reduce winter heating demands and summer cooling loads by 5 to 10%
- Reduce electricity consumption and peak loads by an additional 5-10%