# A Sustainability Analysis Based on the LCA-Energy-Carbon Emission Approach in the Building System
## 2 Material and Methods
### LCA-Emergy Introduction
#### 2.2.2 LCA-Emergy Model  
1. Solar irradiation calculation model The solar energy can be obtained from Equation (1), as follows: \[E_{S}=A\times J\times(1-\beta)\times T_{\mathrm{C}}\times T_{UEVs}\] (1) where \(E_{S}\) represents the solar energy in the construction process; \(A\) is the site surface; \(J\) is the solar radiation amount (3.5 \(\times\) 10\({}^{9}\) J/m\({}^{2}\)) [72]; \(\beta\) is the surface albedo (0.7); \(T_{\mathrm{C}}\) is the construction time; \(T_{UEVs}\) is the unit energy values. Figure 1: Basic study framework and implementation path. 2. Mass calculation model  
The mass represents the materials in the construction system and the energy calculation model equation is calculated as follows [34,64]:  
\[E_{\text{mass}}=\sum_{i=1}^{n}Q_{i}\times T_{U1} \tag{2}\]  
where \(E_{\text{mass}}\) is the energy value of mass; \(Q_{i}\) is mass amount; \(T_{U1}\) represents the unit energy value. 3. Electricity calculation model  
The electricity calculation equation can be obtained, as follows:  
\[E_{\text{e}}=L\times T_{U\text{e}} \tag{3}\]  
where \(E_{\text{e}}\) is the energy of electricity in the building system; \(L\) is the electricity quantity; \(T_{U\text{e}}\) is the unit energy value of electricity. 4. Water  
The water energy has two aspects. On the one hand, the energy should be calculated in the building demolition and construction stage. The specific Equation (4) can be used, as follows:  
\[E_{water}=V\times\rho\times G\times UEV_{w} \tag{4}\]  
where \(E_{water}\) is the water energy; \(V\) is the water volume; \(\rho\) is the water density; \(G\) is the Gibbs energy of water (4.92 J/g); \(UEV_{w}\) is the water transformity. On the other hand, the water energy should also be considered in the operation phase and the equation can be utilized as (5). \[F_{water}=V_{o}\times N_{o}\times T_{o}\times\rho\times G\times UEV_{w} \tag{5}\]  
where \(F_{water}\) is the water energy in the building operation stage; \(V_{o}\) is the water volume per day for one person (25 L/d/p); \(N_{o}\) is the employee number (the number is 200); \(T_{o}\) is the working time (280 days in this study). 5. Diesel fuel energy calculation model  
Figure 2: LCA–Emergy diagram of the building system. Because of the machinery used, diesel fuel is necessary for the building system. The equation can be obtained as follows:  
\[E_{\text{diesel}}=\mu\times\chi\times UEV_{d} \tag{6}\]  
where \(E_{\text{diesel}}\) is the energy of the diesel fuel; \(\mu\) is the amount of diesel oil used in the buildings system; \(\chi\) is the calorific value of diesel fuel; \(UEV_{d}\) is the unit energy value of diesel fuel. (6) Gasline energy calculation model  
The energy value can be calculated as follows:  
\[E_{gasoline}=\phi\times\varphi\times UEV_{g} \tag{7}\]  
where \(E_{gasoline}\) is the gasoline energy; \(\phi\) is the gasoline quantity; \(\varphi\) is the calorific value of gasoline; \(UEV_{g}\) is the unit energy value of gasoline. (7) Human labor energy calculation model  
The energy of human labor can be obtained, as follows:  
\[E_{H}=L_{T}\times N_{P}\times T_{d}\times UEV_{H} \tag{8}\]  
where \(E_{H}\) is the energy of human labor; \(L_{T}\) is the working time (8 h); \(N_{P}\) is the number of employed workers; \(T_{d}\) is the working day; \(UEV_{H}\) is the unit energy value of human labor. (8) Energy indexes  
Several indicators have been adopted to evaluate the ecological status in this paper. For example:  
1. Renewable input (R\({}_{i}\)) represents the energy input of renewable resources, which has a positive effect on the sustainability in the building system. The calculation formula is as follows: Renewable input (Ri) = Renewable energy/Total energy. 2. Nonrenewable resource (N\({}_{s}\)) is energy input proportion of non-renewable resources. A higher proportion demonstrates a less sustainable role. The calculation formula is as follows: Nonrenewable resource (N\({}_{s}\)) = Non-renewable energy/Total energy. 3.