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What is the White Roofs Project?

A new craze is sweeping the globe, led by an American team of activists. This is the White Roofs Project, which aims to create tangible environmental change and a reduction in energy use - and by proxy, electricity prices.

The team say their goal is to encourage world citizens to employ a solar-reflective white coating on their roofs. This can reflect up to 90 per cent of sunlight, rather than absorbing heat, which is what darker roofs do.

Black roofs only reflect around 20 per cent of light, according to the team. So lightening up the colour of your roof could reflect the sun back into the atmosphere, which can also help to lower the Earth's temperature.

They say the benefits of switching to white roofs can be measured by the solar reflectance index, or SRI. This gives an indication of how much solar heat can be reflected by the surface as well as the thermal emittance, which is the amount of heat absorbed.

White roofs can reduce the amount of summer energy used to cool down urban hot spots by around 10 - 40 per cent, according to project leaders, which means you could lower the amount of hard earned cash that goes to your electricity suppliers.

How will white painted roofs help you?

The White Roofs Project says there is a measurable increase in ambient urban air temperatures. This means cities are getting warmer as vegetation is replaced by buildings.

This means in summer, those who live in cities use more power and place stress on the power grid. The more people that whiten their roofs, the more savings will be seen. You may not need to run your air conditioning unit as often.

Dark roofs can also have an impact on the temperature of our rivers as the rain falling on roofs absorbs some of the heat radiated by the black paint. This then goes straight into the drain and makes storm water warmer.

What about solar panels?

A White Roofs Project study by Michael Magallanes has found the efficacy of solar photovoltaic (PV) systems can increase when they are placed over a white roof.

Cool roofs reflect sunlight which lessens the heat transfer into the building and reduces the cooling load your air conditioning system will face in summer, and improves the performance of PV panels by creating an optimal roof temperature.

Posted by Liam Tunney.