Building Energy Conservation Topics: What Is Building Energy Efficiency?

1. Basic Concepts

Building energy saving, in developed countries, was originally called “improving the energy efficiency in buildings” to reduce the energy loss in buildings.

It refers to the rational use of energy and continuous improvement of energy utilization efficiency under the condition of ensuring the improvement of building comfort.

(1) Basic Concepts

Building energy efficiency specifically refers to the implementation of energy-saving standards and the use of energy-saving technologies, processes, equipment, materials and products during the planning, design, new construction (reconstruction, expansion), renovation and use of buildings.

This can improve the thermal insulation performance and the efficiency of heating and heating, air conditioning, refrigeration and heating systems, and strengthen the operation and management of building energy systems.

The use of renewable energy, on the premise of ensuring the quality of the indoor thermal environment, increases the thermal resistance of indoor and outdoor energy exchange, so as to reduce the energy consumption of the heating system, air conditioning refrigeration and heating, lighting, and hot water supply due to a large amount of heat consumption.

(2) Comprehensive building energy conservation

Comprehensive building energy saving is the sum of energy saving in every link in the whole life of the building.

It refers to the use of energy-saving building materials, products and equipment in the process of site selection, planning, design, construction and use of buildings, implementing building energy-saving standards, and strengthening the operation and management of energy-saving equipment used in buildings.

Reasonably design the thermal performance of the building envelope, improve the operation efficiency of heating, cooling, lighting, ventilation, water supply and drainage, and piping systems, and use renewable energy. Reduce building energy consumption, rational and efficient use of energy.

Comprehensive building energy conservation is a systematic project, which must be led by national legislation and the government to make comprehensive and clear policy regulations on building energy conservation, and relevant government departments should formulate comprehensive building energy conservation standards in accordance with the national energy conservation policy.

In order to truly achieve comprehensive building energy conservation, the design, construction, supervision and management departments at all levels, developers, operation management departments, users and other links must strictly follow the provisions of the national energy-saving policy and energy-saving standards to fully implement various energy-saving measures, so that every citizen can truly establish a comprehensive concept of building energy-saving and truly implement building energy-saving.

Building energy-saving testing determines whether the completed and accepted projects meet the energy-saving requirements through a series of national standards.

GB 50411-2007 “Code for Acceptance of Construction Quality of Building Energy Conservation Projects” on the indoor temperature, the hydraulic balance of the outdoor pipe network of the heating system, the water replenishment rate of the heating system, the heat transfer efficiency of the outdoor pipe network, the air volume of each air outlet, ventilation and The total air volume of the air-conditioning system, the water flow of the air-conditioning unit, the total flow of cold and hot water in the air-conditioning system, the total flow of cooling water, the average illuminance and the lighting power density are tested for energy saving.

The energy-saving testing of public buildings is based on JGJ/T 177-2009 “Energy-saving Testing Standards for Public Buildings”. Consistency of water temperature, temperature difference between supply and return water in water system, pump efficiency, energy efficiency coefficient of cooling source system, power consumption per unit air volume of fan, fresh air volume, balance of constant air volume system, outdoor temperature of heat source (dispatching center, thermal station), etc. for energy-saving testing .

Residential building energy-saving testing is based on JGJ132-2009 “Residential Building Energy-saving Testing Standards” for the average indoor temperature, the heat transfer coefficient of the main part of the envelope structure, the inner surface temperature of the thermal bridge part of the outer envelope structure, the thermal defects of the outer envelope structure, and the outer envelope. The thermal insulation performance of the protective structure, the hydraulic balance of the outdoor pipe network, the water replenishment rate, the heat loss rate of the outdoor pipe network, the operation efficiency of the boiler, the ratio of power consumption and heat transmission, etc. are tested for energy saving.

2. Present situation

The current status of building energy conservation is divided into the following three points:

(1) Building energy consumption accounts for about 1/3 of the total social energy consumption. The total building energy consumption in my country is increasing year by year, and its proportion in the total energy consumption has risen from 10% in the late 1970s to 10%. 27.45%.

In the international developed countries, the building energy consumption generally accounts for about 33% of the national total energy consumption.

Based on this inference, research by the Science and Technology Department of the Ministry of Construction of the People’s Republic of China shows that with the acceleration of urbanization and the improvement of people’s quality of life, the proportion of building energy consumption in my country will eventually rise to about 35%.

With such a huge proportion, building energy consumption has become the soft underbelly of my country’s economic development.

(2) The proportion of high-energy-consuming buildings is large, aggravating the energy crisis.

Until the end of 2002, the area of energy-saving buildings in my country was only 230 million square meters.

More than 40 billion square meters of built houses in my country belong to high-energy-consuming buildings, with a huge total amount and a potential huge energy crisis.

As pointed out by the relevant person in charge of the Ministry of Construction, by the end of 2000, the annual commercial energy consumption of buildings in my country totaled 376 million tons of standard coal, accounting for 27.6% of the total final energy consumption of the whole society. The “contribution rate” has reached 25%.

Due to the large proportion of high-energy-consuming buildings, the northern heating area alone consumes 18 million tons of standard coal every year, with a direct economic loss of 7 billion yuan and an additional carbon dioxide emission of 520,000 tons.

If this situation is allowed to continue to develop, by 2030, my country’s building energy consumption will reach the standard of 108.9 billion tons; by 2030, the summer peak load of air conditioners will be equivalent to the full load capacity of 10 Three Gorges Power Stations, which will be a very amazing quantity.

According to analysis, my country is in a booming period of construction. The area of houses built every year is as high as 1.6 billion to 2 billion square meters, which is more than the sum of the annual built-up area of all developed countries, and more than 97% of buildings are high-energy-consumption buildings.

With such a construction growth rate, it is expected that by 2020, the national high-energy-consuming building area will reach 70 billion square meters.

Therefore, if we do not start to pay attention to building energy-saving design, it will directly exacerbate the energy crisis.

(3) my country’s building energy efficiency is backward and needs to be improved urgently. After the energy crisis in the 1970s, developed countries began to study and implement building energy efficiency technologies, but my country ignored this aspect.

Today, my country’s building energy efficiency level is far behind developed countries.

For example, the thermal function of the envelope structure of most heating areas in China is much worse than that of developed countries with similar climates.

The heat transfer coefficient of exterior walls is 3.5 to 4.5 times that of them, exterior windows are 2 to 3 times, roofs are 3 to 6 times, and the air infiltration of doors and windows is 3 to 6 times.

The actual annual heating energy consumption of residential buildings in European countries has generally reached 6 liters of oil per square meter, which is equivalent to 8.57 kg of standard coal per square meter. To reach 12.5 kg, about 1.5 times that of European countries.

For example, in Germany, which has roughly the same climatic conditions as Beijing, the energy consumption standards for building heating before 1984 were similar to the current level in Beijing, with an annual consumption of 24.6 to 30.8 kg of standard coal per square meter, but by 2001, the figure in Germany had dropped to 3.7 to 8.6 kilograms of standard coal per square meter, its building energy consumption has been reduced to about 1/3 of the original, while Beijing has always been 22.45.