Green Roofs

In many crowded cities, finding space for parks and gardens is very difficult. One creative solution is to use a space that is usually left empty: the roof. A "green roof" is the roof of a building that is partly or completely covered with growing plants. Once seen only on a few special buildings, green roofs are now （ 1 ） in cities around the world.

Green roofs offer several benefits. The layer of plants and soil keeps the building cooler in summer and warmer in winter, which means the people inside use less energy for heating and cooling. The plants also soak up rainwater, so less water rushes into the streets during heavy storms. （ 2 ）, green roofs can lower the temperature of the whole city, helping to fight the heat that builds up among concrete buildings.

There are some challenges, however. A green roof is much heavier than a normal roof, so the building must be strong enough to support the extra weight. The plants also need regular care, especially while they are still young. （ 3 ） these difficulties, many city governments now encourage green roofs by offering money to building owners who create them. As cities grow hotter and more crowded, green roofs are likely to become even more common. Birds, bees, and butterflies are also drawn to these small green spaces high above the busy streets. Some architects now plan for green roofs from the very start, while a new building is still just a drawing on paper. In time, gardens in the sky may become a normal part of city life.