Students at the Calhoun School in New York City have much more than a roof over their heads. They have a rooftop garden, with lush grass, colorful flowers and fragrant herbs. "Green roofs" are sprouting up all over, from schools to city skyscrapers. And roofs aren't the only things going green. Architects are finding all sorts of new ways to build buildings that are easier on the environment. These schools, homes, and offices are called "green buildings".
Normally it takes a lot of energy to run appliances. Too often, that energy comes from burning fossil fuels. So green buildings are designed to do all these things with much less energy. An energy-smart building starts with thick walls. A layer of insulation (隔热材料) traps air to stop heat from passing through. That keeps heat inside in the winter, and keeps heat outside in the summer. This saves energy for heating and cooling.
Heat pumps are another power-saving way to stay comfortable. A ground heat pump moves heat through pipes that run through the ground next to the building. A few feet under the ground, the temperature stays around 10℃ all year round. Water flowing around the pipes helps heat the building in winter and cool it in summer.
Another way to build green is to use recycled materials. That saves the cost and pollution of manufacturing something new. In the Chicago Center for Green Technology, the ceiling tiles (瓷砖) are made of pressed newspaper. The bathroom floors are tiled with recycled glass, and the stall walls are recycled plastic. Builders have found many creative ways to re-use old materials.
As more people become concerned about climate change, more buildings are going green. Green buildings produce less of the gases that warm the planet. City planners like green buildings because they save money. And they are healthier for the people who work and live inside. But you don't need to build a whole new building. Simple changes like shading windows and planting trees can make any home greener—and a better Earth home for us all.
