As cities grow, open spaces, trees and other greenery, and other naturally occurring surfaces diminish, replaced by concrete and asphalt surfaces. When this happens, the heat absorbed by these surfaces has nowhere to go, and so is radiated and reflected into the immediate surrounding areas. This creates an urban heat island.
This leads to an increase in heat in the immediately surrounding areas, making temperatures a few degrees hotter than the actual weather. This causes discomfort to residents of the area and can also incur damage in the form of heat-damaged structures.
There is also a human cost associated with urban heat islands. Heat-related medical emergencies such as heat stroke become more prevalent in such areas as the heat can go up to dangerous levels. The EPA has taken stock of this phenomenon and is now advising cities to take steps to mitigate it. One such way is the use of solar roofs as a means of making cities cooler and more comfortable to live in.
How does solar minimize this effect?
Cool Roof Strategy
A cool roof strategy is a one that seeks to use heat absorbing and/or dissipating roofing materials and technologies. Typical roofs use materials that either reflect or absorb and radiate back heat thus significantly reducing the urban heat island effect. Conversely, cool roofs, like solar, can help absorb sun rays and convert them into beneficial energy.
Solar excels at this because of the way the cells are designed and organized to absorb the maximum amount of sunlight. Solar roofs are also designed to trap this heat rather than radiate it back into the environment, something that can help reduce the amount of secondary heat being released into the environment.
When solar roofs are implemented, there is usually a reduced need to construct structures that support the traditional electric grid. Such a scenario can play out in several ways. If a new estate is being built with nothing but solar power, there is a possibility that some open spaces can be retained as fallow ground in places where utility implements would have been installed.
While the gains at this level would be marginal, implementation of this strategy across several thousand estates can help move the needle in reducing the urban heat island effect.
This approach offers the greatest promise of reducing heat in urban settings. By combining the cool roof strategy with other strategies like green roofing, planting more trees and vegetation, cool paving and general smart city growth, a lot of ground can be covered.
All these strategies have one thing in common in that they all absorb and dissipate heat in an efficient and sustainable manner. The EPA recommends these measures, among others, to cities grappling with the urban heat island effect or anticipating it as open spaces and greenery levels go down.
Many cities have a high incentive to deal with this issue because of its effect on residents and visitors to the area. If street-level temperatures are unbearable, it is possible that tourists and potential new residents may shy away from the area in favor of other cooler and sustainable cities.