New commercial buildings in France must now install either a partial green roof or solar panels under new legislation passed by the parliament last week. The ruling aims to ensure commercial buildings contribute to mitigating climate change, either through the cooling effect of plants in terms of the urban heat island effect and reduced cooling needs for the individual building due to the insulation provided by rooftop plantings; or through increased use of renewable energy.

A French study in 2014 found that solar panels themselves also contributed to reducing the urban heat island effect, both through shading a building’s roof therefore reducing radiant heat and also by reducing reliance on high-emissions energy while simultaneously reducing the need to use electricity for cooling by about 12 per cent.