ENVIRONMENTAL BENEFITSEnvironmental MaskingA green roof offers the design potential for a building to blend into its surrounding landscape thus replacing the permeable land otherwise lost to the construction. This can prove to be beneficial when the project is submitted for planning approval.Practical Use of Waste MaterialsMany recycled or waste materials are used in green roofs, which have minimal impact on the environment, and products such as our waterproofing membranes, drainage layers and growing mediums incorporate these elements without detriment to performance of the system. Urban Heat Island Efect and the Control of Air HumidityThe urban heat island effect is the difference in temperature between urban areas and the surrounding countryside. In large cities this can be as much as 5°C. This happens because large building surfaces will both reflect and radiate solar energy within a built up area, which will not dissipate fully overnight. The substrate of a green roof will absorb some of this heat and the natural evaporation of water from both the plants and soil helps to cool and humidify the air, thus lowering the ambient air temperature.Ground Based OzoneA green roof will reduce the rate by which ground based ozone is produced by lowering the ambient air temperature, which is a contributory factor.Improved Air QualityA natural process of plants is photosynthesis, where the energy from sunlight is used to convert water and carbon dioxide into sugars and oxygen. The chemical equation of photosynthesis shows that six molecules of CO2 and six molecules of H2O are converted into one molecule of sugar and six molecules of O2. This is important for the environment and supports the view that the more vegetation that is planted in cities the better the air quality will be. The vegetation will also attract airborne pollutants and dust particles, thus removing them from the local atmosphere.bauder.ieoC3332313029108Storm Water ManagementGreen roofs retain rainwater by storing it in the plants and substrate, which then evaporates back into the atmosphere. By slowing down and reducing the levels of rainwater entering the drainage system, less strain is put on our older and often inadequate sewage systems, thus helping to mitigate flooding. A green roof will retain 40-90% of average rainfall, over the course of a calendar year.Illustration of Rainfall (mm)2800mmand aboveUp to 750mmand above1250mmand above1700mmand aboveThe annual rainfall map above clearly shows that the west of the country has more rainfall. When using sedum blanket systems along the east coast of the UK or in exposed or steep south facing situations, provision for irrigation is recommended. Annual average 1971 - 2000The above table indicates the percentage (%) of annual rainfall retention as a factor of the depth of substrate of the green roof system.The figures for this table are based on 650 - 800 mm annual rainfall. This relates to most of England. However, in Cornwall, Devon, Somerset, the North West of England and Ireland, the annual rainfall figures can, in localised areas, be up to double the rest of England. Wales can expect 800 - 2,000mm of annual rainfall and Scotland between 800 and up to 3,200mm in the highlands.In areas with higher annual rainfall than 800mm, the percentage of water retention will obviously be lower. Likewise, a low annual rainfall will lead to a greater percentage of retained water.For detailed and specific information on rainfall, contact the Met Office. www.metoffice.comWater Retention in Extensive Gren rofs(Translated from the German FLL Green Roof Guidelines)

FINANCIAL BENEFITSReduced Building Running CostsThe enhanced thermal performance provided by a green roof provides a more balanced temperature within the building. This reduces heating costs in the winter and air conditioning expenses during the summer. Reduced Lifecycle CostsThe main reduction in lifecycle costs comes from the green roof providing protection from the damaging effects of the weather, which effectively 'ages' the waterproofing, thus the time span between replacement is extended significantly, and in many cases replacement will become unnecessary.Aid to Planning ConsentMany local authorities favour planning proposals that incorporate green roofs within the application, particularly if it meets their policies towards a sustainable environment.Offset Construction CostsIn large construction projects a green roof can mean that storm water holding tanks are reduced in size or no longer required, as the roof itself will retain much of the rainfall. Horizontal Roofs PossibleScreed to falls is an expensive element of the construction. As a green roof can be installed on a horizontal deck, the cost of this can be offset by the savings made on the screed.Creates an Amenity SpaceThe roof is often an under-utilised asset of a building, as it offers the unique potential to replace the land lost to the construction as reusable space. Large roof areas covering underground car parks can provide parkland or sports facilities.Increases Property ValueAs an additional dimension is created, the property will maximise the potential available for the site, and so increase the value.Productivity in the WorkplaceResearch has shown that people working in offices that overlook green spaces have a higher productivity than those with a poorer outlook on to hard, impervious buildings. The evidence shows that there is a reduction in stress levels if people have visual and personal contact with natural greenery and that physically they benefit from the cleaner air.HealthHospitals are greening overlooked roofs or incorporating garden areas for the benefit of patients as they find that this speeds recovery. Some able patients are also encouraged to access the gardens and to actively maintain them as part of therapeutic exercise.Noise ReductionGreen roofs have excellent acoustic qualities for both external sound (up to 3dB) and internal noise (up to 8dB). This can prove to be both economically and environmentally effective when used on structures close to airports or industrial developments.Thermal PerformanceWhilst a green roof cannot be incorporated within insulation calculations for current Part L regulations, it will provide greater thermal performance for the roof, which will vary depending on the time of year and the amount of water held within the system. ECOLOGICAL BENEFITSCreating a Natural Habitat for Plants and BirdsBoth plants and the smaller elements of wildlife on a site are encouraged to remain in the area, as a habitat is recreated that would otherwise be lost to the footprint of the construction.Aids BiodiversityA green roof can provide a habitat specifically designed to support a particular species of plant or wildlife. The ongoing natural colonisation and cross-fertilisation of plants allows for a truly natural habitat to develop, though a helping hand should be given to nature by initially incorporating certain species of flora. The vegetation when established is generally self sustaining and so requires minimal maintenance.TECHNICAL BENEFITSProtects the WaterproofingA green roof provides a protective covering for the waterproofing from UV damage and thermal movement. Research has shown that the life expectancy of the waterproofing is significantly extended and in many cases may last the estimated design life of the building, which can eliminate future replacement costs. 109 bauder.co.ukGREEN ROOFLANDSCAPING