Bonne Nouvelle! French Law Mandates Green Roofs, Solar Panels

In case you need a reason to say “vive la France,” the French parliament just gave you one.

Last week, the governing body passed a law that requires new buildings in commercial zones to be partially covered in either plants or solar panels, Agence France-Presse reported.

French environmental activists urged the government to pass a law requiring new buildings to cover their entire roofs with plants. However, the government managed to work with the activists, who support the new law.

France lags behind in PV capacity

France lags behind other European countries when it comes to solar deployment. France only installed 613 megawatts of solar photovoltaics in 2013 amongst countries that installed at least 1 gigawatt in previous years, a 2014 report by the European Photovoltaic Industry Association (EPIA) found. In 2011, France installed 1.77 gigawatts.

Solar PV capacity in France has increased much more slowly than in Germany, Spain or Italy, Reuters reported in November. In June, France had 5,095 megawatts of PV capacity, accounting for 1 percent of the energy consumption in the first half of 2014. Neighboring Germany had almost 37,000 MW.

Green roofs and PV panels reduce urban heat island

Urban regions are warmer than surrounding rural areas. For example, Fresno, a city in central California, is at least 4 to 5 degrees Fahrenheit warmer than its surrounding rural areas. Four or 5 degrees may seem like a minuscule difference, but 104 degrees Fahrenheit as opposed to 100 degrees is more intolerable.

Why are urban areas warmer? Buildings and roads have replaced open land and vegetation, the U.S. Environmental Protection Agency (EPA) explains. That means that surfaces which were moist and permeable become dry and impermeable. This causes urban regions to become warmer, forming an island of higher temperatures -- known as an urban heat island.

Heat islands cause a number of negative impacts, according to the EPA, including:

• Increased energy consumption to compensate for higher summer temperatures


• Increased emissions of air pollutants and greenhouse gases from power plants


• Impaired water quality because hot pavement and rooftop surfaces transfer excess heat to stormwater that drains into storm sewers and increases water temperatures as it is released into streams, rivers, ponds and lakes

One way to reduce the urban heat island effect is by installing green roofs. Although a green roof is costlier than a conventional roof, it will save about $200,000 over its lifetime, a Michigan State University research team found. Almost two-thirds of the savings come from decreased energy needs.

Green roofs are not the only way to cool an urban heat island. A 2014 French study discovered that solar panels also reduce the effect. In other words, solar panels provide energy that is good for the environment and provide environmental benefits by reducing the urban heat island effect. Très bon!

Image credit: David Werner