The construction industry consumes a large quantity of energy and resources and creates a huge amount of pollution. In the United States, building and development account for 39% of the country's total energy use, 12% of total water consumption,68% of total electricity consumption and 38% of carbon dioxide emissions（二氧化碳排放）, according to the Environment Protection Agency.

　　Green buildings use less energy, water, create less waste, and are healthier to live, work, and go to school in than standard buildings. Builders of green buildings use techniques that use resources more efficiently during the entire building cycle-construction, restoration, operation, maintenance（维护）and demolition（拆毁）-than those who construct more regular buildings.

　　The environmental benefits of building green include the protection of ecosystems（生态系统）and biodiversity, improved air and water quality, less waste flowing into streams, and the protection of natural resources. Green buildings can also result in lower operating costs because they typically use less energy and fewer materials and improve indoor air quality, improving the health of people who live in such buildings.

　　The process of building green includes technical and artistic planning with nature protection in mind. Building designs often reflect the surrounding environment and natural resources and use renewable building materials such as bamboo and straw. In addition, recycled resources found locally are used for green buildings, reducing the cost and air pollution associated with transporting materials over long distances.

　　Careful site selection is important to minimize（最小化）human impact on the surrounding environment. For example, placing a structure in an area that allows it to take advantage of cool breezes（微风）and sunlight can reduce energy use and expenses. More energy and expense are needed for larger buildings as well, so it is important to build small.

　　Green roofs are another feature of green houses that reduce energy use and cost. These roofs are partly or completely covered with plants, which helps to keep heating and cooling costs, prevent water running off and deal with pollutants.

　　Other features of green buildings often include energy and water conservation, recycling, and waste reduction. In addition, renewable energy sources such as solar power, hydropower（水能）and wind power are used for heat and electricity, which greatly reduces costs and decreases the impact on the environment.

1.What is the text mainly about?

　A. The necessity of promoting energy efficiency.

　B. The process of building green buildings.

C. The benefits and features of green buildings.