There are quite a few on tower office block in the City of London: given the size of those things, the weight issue is less of a problem! And, of course, in the City truly green sites are not feasible so green roofs are very important both for conserving resident species and as islands for birds and insects traversing the great concrete sea ...
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Originally Posted by svenrufus  The problem with the green roof idea is the weight, which - particularly for sedum which needs basically crushed rubble as a substrate - is significantly higher than for a conventional roof, so needs more sustantial infrastructure in the construction of the rest of the building to support it, so it comes at a cost, both financial and resource. I don't know enough to be sure if the cost justifies the effort, given the benefits of water capture, thermal insulation and habitat creation. I like the idea on a superficial level, but it is possible that it might not turn out to be the best use of resources for the desired result, and that money be better spent doing somthing on an offsite conservation basis. [I should find this out as I have advocated their use in the past when looking at mitigation and other planning issues for clients - any other views here would be welcome]
Sven |