Comparison of Energy Consumption and Carbon Emissions from Building Operation Between China and Other Countries

2.1 Energy Consumption and GHG Emissions in the Global Building Sector

2.1.1 Energy Consumption by Global Building Operation

According to the International Energy Agency’s (IEA) calculation of global energy use and emissions of the building sector (as shown in the figure below), in 2021, the embodied energy consumption during the global building construction stage (including building and infrastructure construction) and the building operation energy consumption accounted for 37% of the total global energy consumption, in which the embodied energy consumption during building and infrastructure construction accounted for 7% and the energy consumed during the operation stage accounted for 30%. In 2021, the total global CO₂ emissions (including energy-related and industrial process emissions) were 36.3 Gt CO₂, in which the embodied CO₂ emissions from construction (including building and infrastructure construction) in the construction sector accounted for 12% and the CO₂ emissions from building operation accounted for 28% (Fig. 2.1).

Fig. 2.1

Source 2022 Global Status Report for Buildings and Construction, International Energy Agency. The construction sector involves civil building construction, production building construction, and infrastructure construction. This figure uses the terminal energy consumption data provided by IEA, which is obtained through the direct addition of heat consumption for heating, electricity consumption of buildings, and terminal use of various energy types. The electricity consumption is converted to primary energy using a calorific value equivalent method. This conversion method is different from that used in the comparison of building energy consumption among countries in the ensuing part of this research, so it should be treated differently in data comparison

Energy use and CO₂ emissions in the global building sector (2021).

According to BERC’s calculation of China’s building energy use and emissions, in 2021, China’s embodied energy use and operational energy use in the building sector accounted for 31% of the total social energy use,¹ which was close to the global level. However, China’s building embodied energy use was 10% of the total social energy use, higher than 7% of the global level. If coupled with the embodied energy use for production building and infrastructure construction, China’s building embodied energy use will be up to 26% of the total social energy use. The building operation energy use accounted for 21% of the total and was still lower than the global average. In the future, the share of China’s building sector energy use will continue to increase with economic and social development and the improvement of living standards.

In terms of CO₂ emissions, in 2021, China’s total social carbon emissions (including energy-related and industrial process emissions) were about 11.5 Gt CO₂, in which the embodied CO₂ emissions from building construction and the CO₂ emissions from building operation accounted for approximately 33%, including 14% from building construction and 19% from building operation (Fig. 2.2). If the energy-related CO₂ emissions were considered only, the CO₂ emissions from energy consumption of the whole society in China could be about 10.3 Gt CO₂ in 2021, including about 22% from building operation.

Fig. 2.2

Source: Estimation with CBEEM of BERC, Tsinghua University. The construction sector involves the construction of civil buildings, production buildings, and infrastructures. The diagram on the right illustrates the structure of China’s total social carbon emissions (including energy-related and industrial process emissions)

China’s building energy use and CO₂ emissions (2021).

As China’s urbanization is still ongoing, the major share of energy consumption and emission has come from building and infrastructure construction. The share of embodied energy consumption from building construction in China is higher than the global average and also higher than that of member countries of the Organization for Economic Co-operation and Development (OECD) that have already been urbanized. However, compared with those in OECD member countries, the building operation energy consumption and carbon emissions in China are at a lower level. As urbanization becomes slower in China, the proportions of building operation energy consumption and related emissions in the social total will further increase. China will gradually shift the focus of its building energy efficiency and low-carbon work from the low-carbon development of new buildings to the low-carbon operation of existing ones.

2.1.2 Boundaries and Comparative Study Methods of Building Energy Consumption and Emissions

Comparing building energy consumption among countries is an important means to know the building energy consumption in China, analyze its future development trend, and design the paths of building energy saving. In this section, the building operation energy consumption and carbon emission data of countries in the world are collected and analyzed through comparison. To ensure data comparability and better reflect actual energy use, the energy consumption data in this study only included commodity energy and did not include biomass energy that was not circulating.

Two types of data are collected to compare building energy consumption among countries. The first type includes population, the number of households, and the floor area of buildings. The other is building energy consumption data, which mainly includes the total consumption of electricity, heat, coal, natural gas, and other fuels during building operation. The building energy data of countries around the globe collected in this study mainly comes from two sources:

• (1) Databases of international organizations and agencies: mainly including IEA, Odyssee, World Bank, and Eurostat databases;

• (2) Official statistics of countries: For example, Japan’s data mainly comes from the Statistical Handbook of Japan and the Japan Statistical Yearbook published by the Statistics Bureau of Japan. The data on the US is mainly sourced from the periodic surveys conducted on representative buildings of the country and the statistics released per year by the Energy Information Administration(EIA). Canada’s data mainly comes from Natural Resources Canada. The data on South Korea mainly comes from the building information statistics of the Ministry of Land, Infrastructure, and Transport and the KOSIS data. The data of India is mainly from the National Statistical Office (NSO) and the Ministry of Statistics and Programme Implementation (MoSPI).

• (3) Some published research reports and literature also provide important support and reference for this study as they have studied the building energy and emissions in various countries and provided quantitative data.

• (1) Calculation of Building Energy Consumption

In the analysis and comparison of building energy consumption, it is necessary to add the consumption of all types of energy in buildings together to get the total building energy consumption, on account of the different percentages of electricity, fuels, and heat used for building operation in various countries. At present, the end-use energy consumption method and the primary energy consumption method are commonly used for calculation. In the context of the low-carbon energy transition, the development trend of building energy use in various countries is to achieve full electrification. With the gradual increase in the percentage of electricity in the energy structure, it will be more meaningful to convert all categories of energy use into electricity and then add them together to get the total energy consumption of buildings. Therefore, the total energy consumption of buildings is calculated in this section through the conversion of various types of energy into electricity. To decouple the level of building energy use and the level of the energy conversion system, a unified energy conversion factor benchmark is used for the conversion between each fuel and electricity in this study. Under the principle of the energy conversion factor benchmark, the total global building energy use can be directly allocated to the global primary energy, and the energy conversion systems have positive and negative values respectively to reflect their efficiency (high or low) and energy structure (good or bad), and the sum is zero. The energy conversion factor benchmark theoretically means the global average conversion level, namely the global average of the power generation capacity of each fuel. The energy conversion factor benchmark used in this section are listed in the table below (Table 2.1):

Table 2.1 Energy conversion factor benchmark in the calculation of total energy consumption of buildings in various countries

• (2) Calculation of Carbon Emissions from Buildings

The data on carbon emissions from building operation of different countries in this section is sourced from IEA and the calculation results of the CBEEM model by BERC, Tsinghua University. When calculating the total carbon emissions from building operation, the direct carbon emissions, indirect carbon emissions from electricity use, and indirect carbon emissions from heating in buildings were considered. When calculating indirect carbon emissions from building electricity use, the total carbon emissions from electricity generation in each country were divided by the total electricity generation to obtain the average carbon emission factor for electricity use in each country. The carbon emission factor was used to calculate indirect carbon emissions from building electricity use. Carbon emissions from building heat use were calculated with the building heat use and the carbon emission factor per unit of heat. In the study of the building operation energy consumption in each country, various types of energy were converted into electricity by taking a unified conversion factor benchmark as the conversion coefficient. In the study of carbon emissions from building operation in each country, the real carbon emission factor instead of a unified carbon emission factor was used to calculate the real carbon emissions because carbon emissions from buildings are closely related to the energy structure and must be discussed together with the energy structure and the energy conversion system.

For carbon emissions during building operation, each country proposed a goal to reduce carbon emissions in the building sector. The technical pathways and priorities to achieve carbon neutrality in buildings differ between countries. To quantify and analyze the various problems confronted by each country in their attempt to achieve carbon neutrality in the building sector, the carbon emission factors for electricity and heat of each country were used in the calculation. Therefore, differences in the energy mix and efficiency among countries will affect the total amount and intensity of carbon emissions during building operation.

2.2 Energy Consumption and Carbon Emissions in the Building Sector of Different Countries

2.2.1 Building Operation Energy Consumption of Different Countries

Three indicators were selected to compare building energy use across countries: total amount, energy use per capita, and energy use per floor area, as illustrated in Fig. 2.3. The building energy use in this figure was calculated by adopting the electricity-equivalent method to calculate the total energy use of building operation. Energy use intensity per capita and energy use intensity per floor area are shown on the horizontal and vertical axes, respectively. The size of the bubbles represents the total energy use for building operation in specific countries. The bubble chart demonstrates that total energy use for building operation in China was similar to that in the US, although the energy use intensity remained at a lower level. The energy consumption per capita and per floor area in China were far lower than those in the US, Canada, Europe, Japan, and South Korea. The equivalent electricity consumption per capita for building operation was about one-fifth of that in the US and Canada and about half that in Japan and South Korea. The equivalent electricity consumption per floor area for building operation was one-third of that in Canada and half that in the US, Europe, Japan, and South Korea. In the context of tackling climate change and reducing carbon emissions, most countries are carrying out energy transformations, including promoting electrification in the building sector and replacing fossil fuel-based energy with renewable electricity. China needs to develop a different route from developed countries to achieve the target for low carbon emission and energy-saving in the building sector. This would pose a significant challenge to China’s low-carbon and sustainable development in the building sector. Meanwhile, many developing countries are experiencing rapid changes in building energy use. China’s building energy development pathway will serve as an important reference for many countries’ choices, which will further influence global building energy development.

Fig. 2.3

Source CBEEM of BERC, Tsinghua University; World Energy Balances, Energy Efficiency Indicators database (2022 edition) of IEA; WDI database of the World Bank; Satish Kumar (2019) of India.Footnote

Satish Kumar et al. (2019). Estimating India’s commercial building stock to address the energy data challenge. Building Research & Information, 2019, 47, 24–37.

Data from 2021 is adopted for China, data from 2019 for Canada, Germany, and Sweden, and data from 2020 for other countries

Comparison of building operation energy consumption in different countries (electricity equivalent method).

2.2.2 Carbon Emissions from Building Operation in Different Countries

Several countries have set their own goals for achieving carbon neutrality and their paths to achieving carbon neutrality in the building sector. Reducing carbon emissions in the building sector is also one of the important fields to realize carbon neutrality in the whole society. Figure 2.4 shows the total carbon emissions from building operation (bubble chart area), per capita carbon emissions (horizontal axis), and carbon emissions per unit building floor area (vertical axis) of different countries, which are converted according to the energy structures of these countries. The bubble chart of carbon emissions demonstrates that carbon emissions in the building sector are affected not only by the total energy consumption but also by the energy structures of these countries. The per capita carbon emissions and carbon emissions per unit floor area from building operation in China are lower than those in most developed countries due to China’s low building operation energy consumption. However, the energy structure of France is dominated by low-carbon nuclear power; although it has higher building energy use intensity than China does, its carbon intensity is lower than that of China. This also shows that the low-carbon transition of both energy systems and building energy use structure should be achieved in addition to the improvement of energy saving and energy efficiency of buildings on the path toward carbon neutrality.

Fig. 2.4

Source Data of countries in 2020 as provided in the CO₂ Emissions from the Fuel Combustion Highlights 2021 database, IEA. Data from China are the results of 2021 as estimated with CBEEM of BERC, Tsinghua University

Comparison of per capita carbon emissions of different countries (2020).

2.3 Comparison of Energy Consumption and Carbon Emissions from Building Space Heating Among Countries

Energy efficiency improvement and low-carbon transition of building heating are important tasks to achieve carbon neutrality in the building sector. The scenarios of space heating in China varied significantly from north to south. The northern regions mainly adopt the centralized district heating systems with a continuous heating mode, and the key to their energy efficiency improvement and low-carbon transition lies in the gradual improvement of the energy conversion efficiency of heat sources for the centralized heating system and the low-carbon transition of heat sources through the utilization of zero-carbon residual heat. In contrast, the HSCW zones adopt flexible and decentralized electric heat pumps, wall-hung gas boilers, and local electric heating as the main heating methods, and the key to their energy efficiency improvement and low-carbon transition is making decentralized heating appliances more flexible and energy-efficient. These two heating modes are distinct from each other in terms of the operation mode and energy consumption characteristics and thus should not be subject to parallel comparison. Hence, this subsection focuses on northern urban heating (NUH) in China and its comparison with space heating in several European countries with similar climatic and heating conditions. The countries selected for the comparison are Germany, the UK, England, Poland, and four Nordic countries (Sweden, Denmark, Finland, and Norway). The reasons for the differences between NUH and heating in these European countries are analyzed from such influencing factors as building heating demand, heating method, energy efficiency, and primary energy supply structures, thus making suggestions for the low-carbon development of NUH in China.

The European countries involved in this subsection may fall into the following three main categories: (1) Country in which centralized heating is mainly used for urban areas: In Sweden, Denmark, Finland, and Poland, the proportion of district heating is above 50%, and district heating is generally adopted for their urban areas (especially apartment dwellings), like the northern urban areas in China; (2) Country that mainly adopts decentralized heating with electric heating in the majority: In Norway, the heat supplied by all kinds of electric heating appliances makes up 58% of the total heat consumption of buildings; (3) Country that mainly adopts decentralized heating with fossil fuels in the majority: In Germany, the UK and France, household fossil fuel-fired boilers are used as the main heating method, and the heat supplied by electric heating appliances accounts for 4%, 6%, and 15% respectively.

The sources of data on these countries used for comparison are listed in Table 2.2. It should be noted that, although the energy consumption for heating and domestic hot water (DHW) are generally combined into one in the reports published by European statistical agencies, the energy consumption for heating is extracted separately in this subsection to facilitate the comparison with NUH under the same standard.

Table 2.2 Types and sources of data used for comparative study

2.3.1 Heating Demands and Energy Consumption

Figure 2.5 illustrates the comparison of the average heating demands and the average heating degree days (HDD18) among countries: The heating demands per square meter for NUH in China is 0.37 GJ/m², and the average HDD18 weighted by the heating area of provinces is 2,788. The average HDD18 values of Finland and Sweden are obviously higher than those of other involved European countries and the NUH region. The average HDD18 values of Norway, Denmark, and Poland are in the range of 3,400–3,700 and those of France and the UK are lower than those of the NUH region.

Fig. 2.5

Comparison of heat demands and heating degree days among countries

As indicated Fig. 2.5 in the heat demand per unit area in the four Nordic countries is lower although they have colder weather compared with the NUH region and other European countries. The primary reason for this is that Nordic countries generally have higher levels of building insulation. For instance, the building regulations of Sweden specify that the overall heat transfer coefficient of the apartment building envelope should be below 0.4 W/(m²·K) after 2011, which is lower than the design standard for “fourth-stage energy efficient” buildings in Beijing, i.e. 0.6 W/(m²·K). It should be noted that, due to the different statistical standards for data, the heat demands for NUH as shown in Fig. 2.6 represents the statistical data on the heat source side, while that for heating in each European country is calculated based on the building envelope insulation statistics, climatic conditions and indoor loads without considering heat loss in heating pipe networks and overheating. Therefore, the actual heat demands for heating in each European country may deviate from the calculated value indicated in the figure.

Fig. 2.6

Comparison of equivalent electricity consumption for heating among countries (electricity equivalent method)

Figure 2.6 shows the comparison of the heating demands for heating, equivalent electricity consumption per unit heating demand, and the total equivalent electricity consumption for heating in China’s northern urban areas and European countries. The equivalent electricity consumption per unit heating demand for heating in China’s northern urban areas is 95 kWh_e/GJ, less than that in all European countries compared. Because the calculation method of equivalent electricity is to convert the heat supplied from CHP into the reduced electricity generated from CHP compared with pure condensing thermal power, and CHP can be equivalent to electric heat pumps with a Coefficient of Performance (COP) of 4. This equivalent COP is higher than the annual average COP for the operation of most heat pumps under climatic conditions in Northern and Central Europe and much higher than that for general boilers and direct electric heating appliances. Therefore, under the framework of the electricity equivalent method, CHP may be considered to have higher energy conversion efficiency than other heating methods. The percentage of CHP in centralized heating sources in China is above 60%, equivalent to that in Denmark, Finland, and Poland, which have the highest percentage of CHP among European countries. Consequently, when the centralized heating rate in China’s northern urban areas is higher than the overall centralized heating rate in the urban and rural areas of other European countries, the equivalent electricity consumption per unit heating demand for heating in China’s northern urban areas is the lowest in the comparison. And that in Norway, the UK and France that mainly adopt decentralized heating is higher.

2.3.2 Carbon Emissions from Building Heating

The total carbon emissions from space heating in each country may be calculated based on the energy supply structures of building heat sources and the carbon emission factor for each type of fuel used. The total carbon emissions from NUH are 0.49 Gt CO₂, about 1.25 times that from heating in the eight European countries compared. As shown in Fig. 2.7, the carbon emissions per unit heating demand for NUH is 80 kg CO₂/GJ, equivalent to those for Poland, and the carbon emissions per unit area for heating is 30 kg CO₂/m². Norway, with 12 kg CO₂/GJ of carbon emissions per unit heating demand, has the lowest carbon emission intensity among countries adopting decentralized heating, and Sweden, with 18 kg CO₂/GJ of carbon emissions per unit heating demand, has the lowest carbon emission intensity among countries adopting centralized heating. Finland and Denmark have 35 and 38 kg CO₂/GJ of carbon emissions per unit heating demand for heating respectively. The carbon emissions per unit heating demand in the UK, Germany, and France which mainly adopt decentralized heating are approximately 48–68 kg CO₂/GJ.

Fig. 2.7

Comparison of carbon emissions from heating among countries

As revealed in Fig. 2.8, the main heat source for NUH in China is coal-fired CHP (51%), and building heating method in Poland is also dominated by a coal-firing but has decentralized coal-fired boilers as the main method. The carbon dioxide emissions per unit calorific value of coal are about 1.6 times those of gas, therefore China’s northern urban areas and Poland have the highest carbon emission intensity per unit heating demand for heating among the countries compared. Following Poland are the UK and Germany: About three-fourths of space heating for the UK is supplied from natural gas, and the energy supply ratio of biomass energy and zero-carbon electricity is less than one-tenth. Although Germany is less dependent than the UK on natural gas for heating, the total energy supply ratio of coal, oil, and gas has been three-fourths. The percentages of fossil fuels in building heat sources in Norway and Sweden are below 10%, the lowest in the countries compared.

Fig. 2.8

Comparison of the composition of building heat sources among countries. Note other zero-carbon heat sources include geothermal energy, solar thermal, and industrial residual heat

It can be seen from Fig. 2.9 that Norway, Sweden, Finland, and France have higher percentages of electric heating. The power structures are compared among countries: Sweden and Norway only have about 2% of fossil-fueled thermal power, and most of the supplied electricity is zero-carbon electricity; zero-carbon electricity also makes up more than 80% of the power structures of Finland and France; consequently, the carbon emission intensity of electric heating in these four countries is very low. The power structure in China’s northern region is still dominated by fossil-fueled thermal power (about 78%), and the proportion of zero-carbon electricity is expected to be further increased in the future to reduce indirect carbon emissions from electric heating.

Fig. 2.9

Comparison of power structures among countries

European countries have selected the heating methods and energy types according to their own national conditions based on their own natural resource conditions and social and economic development. The major European countries have established improved heating systems suitable for the local heat source conditions and climatic features. At present, China and European countries are actively implementing the low-carbon transition of building heating. China’s northern urban areas and the urban areas of Sweden, Finland, and Denmark have built perfect centralized heating systems and achieved a high proportion of CHP for space heating. Nevertheless, coal-fired CHP remains the main heat source for centralized heating in China, thus China’s carbon emissions are much higher than those of the four Nordic countries. In the future, the northern urban areas in China should continue implementing the renovation of existing buildings to achieve the goal of reduced building heating demands and should combine the comprehensive collection, storage, and utilization of residual heat resources with the seasonal heat storage technology to utilize the year-round industrial surplus heat for building heating in winter and to realize low-carbon heating by relying entirely on the suplus heat from nuclear power, peak shaving thermal power, curtailed wind and solar PV power and process industries as heat sources.