City Rooftops - By: Erik Kerski

Have you ever cycled out of the town after dark? Did you notice the fact that the temperature decreased simply because you left the homes behind? Particularly noticeable at night, when there is very little breeze, you immediately observe precisely how our built up surroundings generates and stores heat and that is then released.

This is called the Urban Heat Island Effect.

If the concrete and bricks of buildings along with the asphalt of streets have replaced the permeable vegetation layers of the natural landscape then an urban heat island is formed.

The particular natural talent of a city to build up and gather heat like this was first realised by a British meteorologist, Luke Howard, during the early 1800's. Since then, urban centers have grown bigger and so have the constructions throughout them. Now we have introduced far more technology, from cars to air-conditioning, which in turn pumps additional heat into the places where we reside.

Satellite expertise today permits us to gauge much more correctly temperatures of our own urban and rural areas. The final results show that we've designed 'islands' inside our natural landscape, which you'll find hotter in comparison with the adjoining natural landscape. The demand for additional cooling because of the rise in temperatures leads to additional energy consumption and additional air pollution. Greater pollution and higher temperatures help make towns and cities much less comfy areas to live in and might even affect the physical health of people which reside and work there.

Stormwater may damage vulnerable ecosystems if it is warmed as it runs off of the non-porous surfaces of buildings and roadways and then released into waterways. Often architects and urban planners need to produce complex systems to channel rainfall away from population centres before it causes concerns Rainwater can sometimes combine together with sewage and cause greater health problems and damage to ecosystems.

Roughly 50 % the world's population lives in cities and also the statistics are generally rising annually. Urban coordinators try to look for means of creating the available liveable space much healthier and more energy-efficient.

Rooftops makes up a large proportion of almost any city's surface area. Most likely because they are generally out of sight, they usually are disregarded, but in fact they symbolize an essential component within the heat island issue. Every object has an ‘albedo' - the pace at which it can reflect radiation from the direct sun light. Surfaces in a town that have an increased albedo are much better because they reflect radiation away from the surface and for that reason assist in keeping buildings much cooler.

Traditional asphalt built-up rooftops possess a low albedo, reflecting just about 26% of the sun's radiation. The actual amount could be as little as 6%. All of the other solar radiation is absorbed which generates heat that remains in the area when there's virtually no wind.

An eco-friendly roof however reflects a lot of the sun's radiation out of the structure as it has a good albedo. It also provides cover from the sun and also heat insulation which ensures you keep the dwelling below it cooler. The vegetative layer holds rainwater, in place of merely warming it and carrying it away. The evaporation of water from the substrate and transpiration of moisture from the greenery acts to cool the rooftop and prevent it from changing into an additional source of urban heat.

Flat roofing systems which can be cooler can play an important role in offsetting the negative impact of the urban heat island.

About the Author

For additional information on flat roofing or green roofs or to take advantage of our full technical advisory service please visit http://www.icb.uk.com

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