The Benefits Of Green Roofs

Green roofs are multifunctional providing a number of significant benefits

• attenuation and treatment of storm water run-off
• absorption of air pollutants and dust
• reduction in the 'urban heat island' effect
• provision of wildlife habitat and meeting biodiversity targets
• attractive open space
• health benefits
• protecting the building fabric from ultra violet radiation and temperature fluctuations
• reducing costs, including drainage, heating, air conditioning

The Potential

There is a huge potential for building-integrated vegetation (green roofs and green facades) to benefit the conservation of biodiversity in urban areas. As an example in Germany, the country that leads the world in roof greening, 13.5 million m2 of green roofs were installed in 2001.

In London alone there are over 28 hectares of roofs that could be converted to green roofs alone not to mention the potential throughout the Capital and the Thames Gateway in terms of new developments. Local authorities throughout the country are beginning to consider green roofs as an effective means of achieving their sustainability objectives. The European Green Roof Association [EFB] considers the UK as probably the largest potential market in Europe for green roofs.

Types Of Green Roofs

Green roofs are typically divided into three categories:

• Intensive (equivalent to parks or gardens) - with deep substrates and high maintenance. Such systems are often referred to as roof gardens
• Semi intensive - these systems are shallower than intensive though allow for a greater variety of plants species and landscape characteristics than extensive
• Extensive - these systems in the UK are generally dominated by sedums and mosses. However there is a growing interest in so called 'brown' roofs or green roofs designed for biodiversity. These are more naturalistic and aim to replicate the ecological character of the local area. This are often cheaper and more sustainable in the long term in regard maintenance