A green roofing system is an extension of the existing roof which involves a high quality water proofing and root repellant system, a drainage system, filter cloth, a lightweight growing medium and plants. Green roof systems may be modular, with drainage layers, filter cloth, growing media and plants already prepared in movable, interlocking grids, or, each component of the system may be installed separately. Green roof development involves the creation of “contained” green space on top of a human-made structure. This green space could be below, at or above grade, but in all cases the plants are not planted in the “ground’. Green roofs can provide a wide range of public and private benefits. Life expectancy is over 50 years.
Advantages (Benefits) of Green Roofing:
1. Green roofs provide thermal insulation and therefore energy costs savings and consequent reduction in carbon dioxide production.
2. Plant activity on green roofs reduces the amount of carbon dioxide in the atmosphere.
3. Green roofs can help to reduce the production of ozone by reducing the heat island effect and by absorbing airborne particles.
4. Green roofs act as noise barriers and are sufficient to provide noise insulation for buildings under flight paths and around airports
5. Green roofs, if designed appropriately, can provide valuable wildlife habitat in cities and help meet local, regional and national biodiversity targets
6. Green roofs reduce the effect of the urban heat island effect
7. Green roofs significantly reduce storm water run off from buildings
8. Green roofs provide visual amenity to green space
9. There is evidence that access to visual green space can have positive effects on health.
10. Innovation in the UK in the use of recycled secondary aggregates as growing mediums can help meet targets to reduce secondary aggregate waste.