Simon Odell covers a recent Sustainable Water Industries Group event, and points to green roof and wall resources

    Green Wall at Edgeware Road, London

    Green roofs and walls continue to be of interest and I was pleased to join the at its latest event at on 13th January.

    The venue is a case study in itself. Designed and completed in 1938 by Ralph Hancock, FRHS, it comprises well-maintained gardens on the 6th floor, one of which is striking for, the size of some of the trees, water features with bridges and live flamingoes. It resembles a small park and only some minor waterlogging of the lawn was apparent to remind me that drainage was impeded.  This was my first visit and I was impressed. And these gardens are open to the public to visit free of charge.

    Moving on to the event itself there were a number of points that struck me.

    Although I would still like to be convinced about the cost-benefit of retrofitting green roofs over providing equivalent landscape functionality elsewhere at ground level, the statistic that 60% of London is roofs brings it home that they are an opportunity, and it only takes a slightly increased load-bearing specification to move beyond sedum to the kind of garden provided at the Roof Gardens. By 2004 there were already 70,000 sq.m of green roofs in London. The techniques have been improving; Black Redstarts are now breeding on green roofs at the Olympics Site.

    Another statistic that impressed me was that by 2030/2040 London is heading for an anticipated deficit of 20000 litres of potable water a day and we need to be seeing rainwater in urban areas as a resource for keeping urban landscapes green rather than depending on drinking water. Water Sensitive Urban Design is just one of a number of themes that the LI has been pursuing with its evidence to the APPG for Excellence in the Built Environment, delivered by Stuart Ryder.

    Green roofs with its links to GI and WSUD is a maturing field and quite a lot of resources already exist (although Technical Committee has not evaluated these and it is not my field), but we were particularly pointed to , supporting the GLA’s Living Roofs Policy and the North American . I have also come across the .

    Blog written by Simon Odell, CMLI, Head of Technical and Professional Services, who is available via email[email protected]

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