Agenda Reports Pack (Public) 15/10/2012, 19.00 - Meetings ...

area can make; further noting that spatial planning was key as well as looking atopportunities arising from re-developments.2.10. The Task Group were concerned about the impact that both side and rearextensions had on the natural drainage of rainwater. Whilst the Task Groupacknowledged that applicants currently were encouraged to compensate for anypermeable land they built on by creating a comparable amount of permeable land ontheir property, by, for example, removing a garden shed and replacing it with apermeable surface, the Task Group felt such an approach was not really practical inHammersmith and Fulham.2.11. The Task Group felt that local residents should be encouraged to be more pro-activein combating the risk of surface water flooding by incorporating various forms ofSUDs into their building plans. For example in small scale developments it was felt itwould be appropriate for local residents to consider adding water butts where spaceand downpipes permitted. For larger scale developments, such as buildingimprovements to housing blocks, it was felt that green roofs were an attractive andviable solution to addressing the problems of surface water flooding.2.12. “Green roofs” are roof-tops that are intentionally vegetated to some degree. Thesecan vary from a full-blown roof garden, through to grassy swards or sedum roofs.They fall into three main categories:► Extensive: Using a relatively thin, lightweight substrate. They are designedto be virtually self-sustaining and should require only a minimum ofmaintenance, perhaps a once-yearly weeding or an application of slowreleasefertiliser to boost growth.► Semi-Intensive: Using a lightweight shallow soil structure to support awider variety of plants including herbs.► Intensive: Intensive roofs are more park-like with easy access and mayinclude anything from kitchen herbs to shrubs and small trees. They areoften designed to be accessible for recreational use and require regularirrigation and regular maintenance.2.13. In oral evidence from Mr Stefan Czeladzinski, the Grounds Maintenance MonitoringOfficer at Hammersmith and Fulham Council, the Task Group heard that it was feltthat sedum matting was not an appropriate green roof solution as it has too shallowa substrate to support it property and does not provide a diversity of plants.2.14. The Task Group heard that in addition to mitigating storm water run-off at source, asthey can potentially retain up to 90% of rainfall within the substrate, green roofs alsooffered other benefits. These include:► Improving the biodiversity on all new and retro fitted sites; thereby alsoensuring building proposals adhered to PPS9, which relates to biodiversityand geological conservation. They also improve the development forecology.► Help ensure that developments are designed to adapt to climate change,ensuring compliance with the UK Climate Policy Change programme.► Reduces urban heat. Green roofs act as ‘mini air conditioners’, cooling andhumidifying the surrounding air with beneficial effects on the immediatearea. This also has the effect of increasing insulation values and reducingthe need for air conditioning.- 19 -Page 178