China’s building energy consumption and the development of solar building applications
China’s building energy consumption development status
For a long time, the world’s energy has mainly relied on fossil fuels such as oil and coal. However, fossil fuels not only have limited reserves, but also produce a large amount of CO2 when burned, causing the earth’s temperature to rise and the ecological environment to deteriorate. What is more worrying is that the reserves of primary energy sources such as coal, oil, and natural gas are rapidly declining. Estimated based on the proven reserves and consumption rate, the world’s main energy oil will be exhausted within 40-50 years, and the mineable life of coal will only be about 200 years. The energy crisis has become the biggest problem that plagues the world.
Building energy consumption mainly refers to energy consumption in heating, air conditioning, hot water supply, cooking, lighting, household appliances, elevators, and ventilation. According to statistics, the proportion of building energy consumption in China’s total energy consumption has reached 27.6% and will continue to grow. China’s current electricity consumption in urban civil buildings accounts for about 25% of China’s total electricity generation, and the amount of coal consumed for urban heating in northern regions accounts for 15% to 20% of China’s non-electricity coal consumption. These values are only the energy consumed by the building’s operation. The construction industry and the housing industry in the construction field are also large consumers of resources. According to statistics, steel consumption accounts for about 20% of China’s total steel production, cement consumption accounts for about 20% of China’s total cement production, and glass consumption accounts for about 15% of China’s total glass production. Reducing energy consumption and saving resources cannot be ignored.
China’s building energy consumption can be divided into the following categories according to its nature: heating energy consumption in the north is about 130 million tons of standard coal/year (equivalent to 370 billion kWh of electricity/year); residential electricity consumption except heating is about 200 billion kWh/year; general non-residential civil buildings (offices, small and medium-sized stores, schools, etc.) other than heating energy consumption; large public buildings energy consumption; rural life energy consumption. Its proportion is shown in Figure 1.
The energy consumed during the use of a building accounts for more than 80% of the energy consumed during its entire life. The energy consumption of urban buildings in China accounts for 20%-22% of the total energy consumption of society. Building energy consumption is affected by the energy consumption per unit building area and the total building volume, and increases with the increase in the total building volume. If China doubles the total amount of urban buildings in the future, the total energy consumption of buildings is likely to more than double. In developed countries such as the United States, Europe, and Japan, the energy consumption level of building operations has grown from 20% to 25% in the period of “manufacturing power” to nearly 40% of the current “financial and technological power” period.
Overview of China’s solar energy building application development
Solar energy is an inexhaustible clean energy, and it is one of the most promising energy sources that mankind can look forward to after the 21st century. The application of solar energy in buildings is the practical field with the most potential for solar energy applications at this stage.
In order to meet the comfort requirements and use needs of residents, modern buildings should have a series of functions such as heating, air conditioning, hot water supply, and power supply (including lighting and electrical appliances). The overall goal of scientific research, technology, product development and engineering applications in the field of solar building applications is to replace conventional energy sources with solar energy to meet the above-mentioned functional requirements of buildings. With the continuous improvement and progress of the world’s solar energy technology, solar energy buildings in the strict sense should be able to use solar energy to meet most of the energy supply required by the comfort level and use functions of the occupants of the house, that is, to achieve the comprehensive utilization of solar energy in the building. At this stage, China can only partially utilize solar energy in buildings. There are many problems to be solved in terms of rationality and practicability, and there is a certain gap between the world’s advanced level, especially in practical engineering applications.
The application technologies of solar energy in buildings include solar water heating, solar heating and heating, solar refrigeration and air conditioning, and solar photovoltaic power generation. The development history of various technologies in China and the current development stage are different.