Why is a white "cool roof" a solution?
A white “cool roof” is a simple and effective climate and cost-savings solution that has already been proven around the world. In countries with a warm climate, such as Southern Europe or North Africa, it is common to see traditionally white buildings. This centuries-old practice is gaining renewed interest to become more energy-efficient and to limit the urban heat island effect.
Since 2010, New York City has repainted 10 million square metres of building roofs in white (1). As a consequence, the use of air conditioners has been reduced by 40%.
From the roofs of supermarkets to those of warehouses and public buildings such as schools and hospitals, initiatives are multiplying (2). In 2015, the Quimper E. Leclerc supermarket covered its 6,097m2 roof with a special white paint. In three years, energy consumption has fallen by more than 45%, from 1,250 to 750 Kva. 175 tons of CO2 are saved per year, as well as €20,000 in electricity savings and €5,000 in maintenance savings, for a low cost (less than €20/m²), providing a high return (3).
The IPCC (Intergovernmental Panel on Climate Change) states that “painting roofs white would save 1Gt/year of greenhouse gas emissions, equivalent to 250 million vehicles”, and that it is one of the quickest and cheapest solutions to adapt and mitigate climate change.