The energy-saving retrofitting of existing buildings refers to the implementation of energy-saving renovation activities for the existing building's enclosing structures, heating systems, heating and cooling systems, lighting equipment, and hot water supply facilities that do not meet the mandatory standards for civil building energy conservation. The energy-saving renovation of existing buildings is an important part of promoting building energy efficiency. The focus of the transformation is to add insulation layers to the external walls, roofs, and through the stairway partition walls; the existing ordinary external doors and windows are replaced with thermal insulation. Performance doors and windows; improve the airtightness of doors and windows to reduce unnecessary indoor and outdoor air leakage. The use of air-conditioning equipment with a higher energy-efficiency ratio and the use of renewable energy sources such as solar energy and geothermal energy in places where conditions permit can achieve energy conservation and resource conservation. Dangerous buildings with poor quality of structure should be gradually dismantled and should not be reformed.

  During the 12th Five-Year Plan period, China has established the goal of energy-saving retrofitting of existing buildings, completing heat metering of existing residential buildings in northern heating areas and energy-saving transformation of more than 400 million square meters. There are existing residential buildings in hot summers and cold winters and hot summers and warm winters. Energy-saving transformation of 50 million square meters, public buildings energy-saving reconstruction of 60 million square meters, has now entered the 13th Five-Year Plan, the goals of existing building energy-saving renovation is still huge. However, according to the existing experience, the energy-saving reconstruction of existing buildings has great resistance, and the key is to require ordinary people to raise awareness of energy conservation. For example, the external thermal insulation of the wall can be used to better extend the life of the building and ensure the indoor coolness and energy saving in the winter and summer. The initial investment is large, but the future energy-saving effect is very good. If the owner’s own energy-saving consciousness has not kept up, this policy of benefiting the people will be difficult to implement.