Building a Life Cycle Carbon Emission Estimation Model Based on an Early Design: 68 Case Studies from China

Abstract

The building sector contributes to 50.9 percent of China’s carbon emissions. Due to the complexity of the assessment process, it is difficult to predict the entire life cycle carbon emissions of a building at the early stage of design. In this study, a whole-life carbon emission estimation model for the early stage of building design is developed based on comparison of the standard calculations and an analysis of stock cases. Firstly, the standard calculation methods in China, Japan and Europe were compared, and the boundary of the model was defined in three parts: production, construction and demolition and operation. Second, information on 68 examples of Chinese buildings was collected and divided into a training set and a test set at a ratio of 7:3. In the training set, the relationship between carbon emissions and the design parameters was searched, and a carbon emission estimation model applicable to different stages was constructed. Finally, the model was applied to the test set for validation. The results show that the calculation error of the model is within ±15%, and it can quickly estimate carbon emissions based on the design factors, which is helpful for carbon emission assessment work in the early stages of design.

Using BIM and LCA to Calculate the Life Cycle Carbon Emissions of Inpatient Building: A Case Study in China

“…4. As shown in Table 6, the consumptions of concrete and steel, in this study, were 0.497 m 3 /m 2 and 68.39 kgCO2/m 2 , respectively, which is in line with the statistical values for concrete (0.3~0.5 m 3 /m 2 ) and steel (40~70 kg/m 2 ) consumption for Chinese buildings [46]. As shown in Figure 5, the total carbon emissions from the transport of building materials were 269.45 tCO2, with a carbon emission per unit area of 17.18 kgCO2/m 2 .…”

“…The main types of energy consumed in the operation of the hospital are electricity, gas, and domestic water. In this study, Designbuilder software was used to assess the building's energy consumption for heating, cooling, lighting, and equipment; Equation (7) was used to calculate the carbon emissions due to electricity and gas consumption; and the carbon emissions due to domestic water consumption were estimated with reference to Equation ( 8) [46]. The energy carbon emission factors required for the above calculations are shown in Table 5.…”

“…where 𝑄 is the cumulative annual cooling consumption (kWh); 𝐶𝑂𝑃 is the coefficient of performance for cooling systems in public buildings, taken as 3.5; 𝑄 is the cumulative annual heat consumption (kWh); 𝜂 is the combined efficiency of the heating system, where the heat source is a gas-fired boiler, taken as 0.85; 𝑞 is the standard calorific value of natural gas, taken as 9.87 kWh/m 3 ; 𝑞 is the combined coal consumption for power generation, taken as 0.33 kgce/kWh; 𝜑 is the conversion factor between natural gas and standard coal, taken as 1.21 kgce/m 3 ; 𝑆 is the area of the building (m 2 ); 𝐸 is the annual lighting energy consumption (kWh/m 2 ); 𝐸 is the annual equipment energy consumption (kWh/m 2 ); 𝐸𝐹 , is the electricity carbon emission factor (kgCO2/kWh); 𝐴 is the design life of the building, taken as 50 years; 𝐶 are the carbon emissions caused by domestic water (kgCO2); 𝐷 is the daily consumption, taken as 2 t/m 2 ; and 𝐸𝐹 is the carbon emission factor of water (kgCO2/t). Maintenance carbon emissions are those from the renewal and maintenance of equipment and components, which can be quickly estimated by multiplying the embodied carbon emissions by a maintenance factor [46], referring to Equations ( 9) and (10).…”

“…where 𝑀 is the maintenance coefficient, taken as 0.65 [46]; 𝑛 , 𝑛 , and 𝑛 are the number of minor, intermediate, and major repairs, respectively.…”

“…Demolition carbon emissions include carbon emissions from demolition and waste disposal. As this is a new building and data on demolition are not available, a quick assessment was made using the empirical formula proposed in a related study [46], as shown in Equation (11).…”