Your cool roof makes an immediate, measurable impact on climate change.
Cool roofs reduce electricity use that, in turn, lowers power plant emissions and the need for new power plants.
Cool roofs, like every building efficiency measure, help address climate change by reducing demand for greenhouse gas emitting power plants. The impact on climate change by this indirect method depends on the amount of coal and natural gas power plants in the local energy mix.
Cool roofs can eliminate the negative impacts of greenhouse gases that have already been emitted. Every 1000 ft2 of dark roof replaced with a cool roof immediately cancels the warming effect of 10 tonnes of greenhouse gases that are already in the atmosphere.
Reflective roofs deliver a much bigger, direct global cooling benefit. Light surfaces reflect more solar energy back into space and absorb less solar energy as heat than a dark surface. The cooling effect generated by switching from dark to light colored surfaces can be quantified and then compared to the warming effect of greenhouse gases in the atmosphere. Studies, such as this one, find that replacing the world’s roofs and pavements with highly reflective materials could have a one-time cooling effect equivalent to removing 44 billion tonnes of CO2 from the atmosphere, an amount roughly equal to the warming effect produced by one year of global man-made emissions. This global cooling effect from reflective surfaces starts immediately after the surface turns from dark to light.
Installing every economically viable cool roof would cancel the warming effect of greenhouse gases produced by half the world’s cars or 500 medium-sized coal plants.
Every 10 square meters (100 square feet) of white roofing will offset the climate warming effect of one tonne of CO2. Assuming the average car emits 4 tonnes of CO2 per year, the combined “offset” potential of replacing the world’s roofs and pavements with highly reflective materials is equivalent to taking all of the world’s approximately 600 million cars off the road for 20 years. Researchers using different calculations and methodology have largely corroborated the size of the offset caused by increased reflectivity.