Solution to Reduce Heat in Urban Areas: “White-colored Roofs”

linfen, one of the most polluted cities in the world (via:Times)

The urban heat island effect has been blamed for the significantly warmer temperatures in cities than is surrounding rural areas. Urban development that modifies the landscape by using materials and by building structures that retain heat has been the cause for this. It exists during both summer and winter and the temperature difference is apparently higher at night than during the day.

In an "urban heat island", the metropolitan area is significantly warmer than its surrounding rural areas

A global simulation by a team at the US National Center for Atmospheric Research in Boulder, Colorado, USA has established an intriguing fact: roofs painted with a highly reflective white paint can cool cities by an average of 0.6 °C!

The urban heat island effect…

Contributes to an elevated temperature of about 2-5 °C in cities compared to surrounding rural areas. This like we mentioned above, is due to the dark city surfaces like asphalt roads and tar roofs.

White roofs…

Reflect most of the heat away (just like wearing a white t-shirt on a hot day can be a little less oppressive than wearing a black one) and therefore has the potential to take away some of the excess heat that accumulates in urban areas.

The computer simulation also established that if all the roofs in a city were painted in white, a 33% reduction could be achieved in the urban heat island effect and that this cooling effect is more prominent during the day, especially in summer.

However…

We must not forget that this is simply what has been demonstrated by a computer model – half the problem for the enormous confusion in predicted climate over the next few decades.

This is also only a concept and there can be many hurdles when it comes to the actual practical application of it. For example the research team points out how this idea could prove to be ineffective if our roofs were to be covered with dust…