Green roofs: building energy savings and the potential for retrofit
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UK researchers reviewed the current state of knowledge of the potential benefits green roofs offer in relation to building energy consumption
Why it matters
According to the researchers, extensive green roofs have a thin substrate layer with low level planting, typically sedum or lawn, and can be very lightweight in structure, while intensive green roofs have a deeper substrate layer to allow deeper rooting plants such as shrubs and trees to survive. A green roof offers a building and its surrounding environment many benefits, like stormwater management, improved water run-off quality, improved urban air quality, extension of roof life and a reduction of the urban heat island effect. Green roofs greatly reduce the proportion of solar radiation that reaches the roof structure beneath as well as offering additional insulation value. It is identified that older buildings benefit greatest from the additional green roof layer. This paper reviewed the current state of knowledge of the potential benefits green roofs offer in relation to building energy consumption.
Reference
The article appears in the October 2010 issue of the Energy and Buildings journal (volume 42, issue 10, pages 1582-1591). Authors: H.F. Castleton, V. Stovin, S.B.M. Beck & J.B. Davison.
Abstract
Green roofs are a passive cooling technique that stop incoming solar radiation from reaching the building structure below. Many studies have been conducted over the past 10 years to consider the potential building energy benefits of green roofs and shown that they can offer benefits in winter heating reduction as well as summer cooling. This paper reviews the current literature and highlights the situations in which the greatest building energy savings can be made. Older buildings with poor existing insulation are deemed to benefit most from a green roof as current building regulations require such high levels of insulation that green roofs are seen to hardly affect annual building energy consumption. As over half of the existing UK building stock was built before any roof insulation was required, it is older buildings that will benefit most from green roofs. The case for retrofitting existing buildings is therefore reviewed and it is found there is strong potential for green roof retrofit in the UK.
