Turning roofs into green spaces has lots of important benefits.
To tackle the intense heat of city life and to protect against global heating, more than two decades ago, Tokyo introduced a clever solution: turning rooftops into green spaces. Thanks to a law called the Nature Conservation Ordinance, many buildings in the city now feature gardens on their roofs, helping to cool down the city and make it more eco-friendly.
Since 2001, this green roof law has required new and renovated buildings - both private and public - to include green spaces. Currently, buildings larger than 5,000 square meters now need a minimum of 25 percent of their roofs to be green, while smaller ones must be at least 20 percent.
To make sure everyone got on board, the city ran public campaigns and shared the benefits of green roofs. These efforts worked: over 5,700 buildings now have green roofs, covering a massive 180 hectares (1.8 million square meters).
Green roofs aren’t just pleasing to look at; they’re fabulous cooling tools. Research shows they can cut rooftop temperatures by up to a whopping 25 degrees Celsius and even lower indoor ceiling temperatures by 1 to 3 degrees Celsius - even in buildings that already have insulation. Plants like grass and perennials are especially good at keeping things cool.
One of the knock-on effects is that by reducing the need for air conditioning in summer and heating in winter, green roofs help cut energy consumption - making them a win-win for both the environment and building owners.
The roofs also bring nature back into the city, enhancing biodiversity. They provide homes for birds, bees, and butterflies, improve air quality, and soak up rainwater to help prevent flooding. They’re good for people, too, giving city dwellers a bit of greenery to enjoy.