Can Green Roofing Mitigate The Urban Heat Island Effect?

It is generally accepted that it is warmer by a few degrees in urbanised areas than their rural counterparts. This is because of a phenomenon called the ‘Urban Heat Island’ effect.
Heat Island Effect

This effect is a result of a number of factors including:

1. Buildings absorb heat (more so as they are dark and unreflective).
2. There is less vegetation. Trees and other plants cool the surrounding area through a process known as evaporative cooling.
3. There is more heat produced through human activity

Poor Air Quality

Urban heat islands tend to create poor air quality. As you could reasonably expect there are more pollutants being pumped into the atmosphere especially from highly congested transport systems, industry as well as whatever we get up to during work and play. In rural areas pollutants are blown away naturally. However, in the highly urbanised areas the urban landscape itself prevents the pollutants from escaping and instead becomes highly concentrated. This problem has sadly been growing steadily since the industrial revolution and now we live side by side with a variety of toxins both indoors and outdoors as a result of human activity.

Mitigating the Urban Heat Island Effect

In recent years, that standard of air quality in our towns and cities has crept on to the political agenda. Many architects are now at the forefront of sustainable building design and certainly there is considerable research (especially in the USA) showing that green infrastructure such as green roofs and walls can improve the quality of our air.
A single green roof in itself may not have the desired impact, but where established in concentration over a large area, then we would see a positive effect. Plants naturally filter out many of the pollutants in the air improving the air that we breathe and coincidently improving the quality of water entering our water systems.

Developing a Green Roof Strategy

It is perhaps not practical to plant trees across all our city rooftops, so in high density locations the use of sedum, grasses and shrubs could be more palatable in terms of cost and the practicalities of retrofitting. Even a 10% increase in green roofs would make a considerable difference in reducing urban air pollution. As usual, when proactive individuals are not taking things into their own hands, it is left to the policy planners to take things forward and though there are positive steps being taken by the likes of the Greater London Authority the rest of the UK are a few steps behind.

What Next For Your Green Roofing Project

To discuss your living roof project call us on 0844 057 0359. We’d be glad to give advice and can supply everything you’ll need for your living roof including a root resistant membrane, your sedum and importantly your lightweight and organic green roof growing medium (IGV GmbH approved and accredited).