Green roofs can provide new living environments as, with the continued urban expansion absorbing the habitats of our indigenous plants, insect and birds; the landscaping of flat roofs offers an effective and practical alternative for the use of the available space, which helps replace and sustain lost habitat.
Increasingly, buildings are being constructed with a green roof and underground parking to provide additional facilities, thereby utilising all available space and maximising the full potential of the building.
Environmental
· Storm water management – soft landscaping helps to reduce the flood risk by retaining large proportions of annual rainfall and reducing rainwater run off, which can be particularly useful as a component within Sustainable Urban Drainage (SUDs) schemes. The levels of water retained are dependant upon the depth of substrate utilised in the landscaping, the greater the depth, the more water is held back on the roof.
· Utilisation of Space – a roof garden provides a recreational area with all the benefits associated with ground level landscaping.
· Environmental masking – this assists in blending the building into its surroundings and replaces the permeable land otherwise lost to the construction.
· Improved air quality – the vegetation retains and reduces gaseous pollutants and dust particles by removing a proportion of them from the immediate environment. In addition, the natural evaporation of water from the plants and soil helps to cool and humidify the air, so lowering the ambient temperature and reducing the heat island effect.
· Photosynthesis is part of a plants’ living process whereby they actively convert carbon dioxide to oxygen. Independent research suggests that, under maximal conditions, each square metre of single leaf surface on an established extensive type planted roof, with a 12 hour day length is estimated to take up (0.3024 x 48) 14.51g of Carbon dioxide and release (0.3024 x 32) 9.68g of oxygen a day.
· Improving sound insulation – green roof landscaping significantly improves the acoustic benefits by reducing the impact of both internal and external noise levels. This is particularly beneficial when the building is sited near to air traffic, industrial developments or busy infrastructure.
· Improving thermal insulation – the addition of substrate onto the roof will provide additional insulation for the structure, which will vary depending on the amount of water being held in the substrate.
Ecological
· Creating a natural habitat for fauna – a green roof will create a habitat in which aphids, invertebrates and other insects can settle or provide a feeding source for their survival.
· Aiding biodiversity – the provision of a living habitat in a place which could otherwise be empty allows for some natural colonisation by native plants whilst also providing a habitat for birds and small animals, thus encouraging a wider spread of species in the area.
Financial
· Reduced carbon footprint through lowering building running costs – the thermal insulation on the building is improved, particularly in the summer, thus providing a more balanced temperature within. This eases heating costs in the winter and can significantly reduce air conditioning expenses during the summer.
