## 2 Methodology
### Environmental Analysis
#### 2.2.2 Building Materials  
The environmental impact of materials includes the energy and water consumed in the provision of the building materials, from the cradle to the door of the factory and their transport to the construction site, whose approximated distance covered by transport is in Andalusia, Spain, is defined [29]. For the transportation of concrete, the truck capacity considered is 24,000 kg, and the distance travelled is 20 km. For other construction materials, it is 2000 kg per truck and 250 km travelled. The average diesel consumption is 26 L/100 km and its emissions are 2.62 \(\times\) 10\({}^{-3}\) tCO\({}_{2}\)/L [56]. The diesel embodied water is 1.26 m\({}^{3}\)/L, ant that of the energy is 57.7 MJ/L. The electricity embodied energy is 3.6 MJ/kWh. With this data, the tons of CO\({}_{2}\) that the transport of each material would entail can be obtained, and this data can subsequently be converted into each environmental indicator (CF, WF, and EE) by using Equations (1) and (2) in Table 1. \begin{table}
\begin{tabular}{l c} \hline
**Impact Source** & **No. Equation** \\
**Machinery Impact** & **Number** \\ \hline IM\({}_{\text{COMB}}\): Combustion engine machinery (MJ; tCO\({}_{2}\)eq; m\({}^{3}\) of water) & \\ \hline IM\({}_{\text{COMB}}\) = V \(\times\) IU\({}_{\text{COMB}}\) & (1) \\ \hline V: diesel consumption (L) & (2) \\ \hline V = (P \(\times\) TU \(\times\) Per) & (2) \\ \hline P: power of the electric engine (kW) & \\ \hline TU: time used (hours) & \\ \hline Per: performance, liter of diesel or petrol consumed per engine power (L/kWh) & \\ \hline IU\({}_{\text{COMB}}\): unit impact of diesel or petrol (MJ/L; tCO\({}_{2}\)eq/L; m\({}^{3}\) of water/L), data: [55] & \\ \hline IMELEC: Electric engine machinery (MJ; tCO\({}_{2}\)eq; m\({}^{3}\)) & \\ \hline IUELEC = (Pot \(\times\) TU) \(\times\) IU\({}_{\text{ELEC}}\) & (3) \\ \hline IUELEC: unit impact of electric mix (MJ/L; tCO\({}_{2}\)eq/L; m\({}^{3}\) of water/L), data: [48; 56] & \\ \hline ECOMB: emission factor of the diesel or petrol (kg CO\({}_{2}\)/L). In Spain: 2.616 kg CO\({}_{2}\)/L [56] & \\ \hline EELEC: emission factor of electric mix (kg CO\({}_{2}\)/kWh). In Spain: 0.248 kg CO\({}_{2}\)/kWh [54] & \\ \hline IMPACT of CONSTRUCTION MATERIALS & \\ \hline IMAT: EE, CF, HF (MJ; tCO\({}_{2}\)eq; m\({}^{3}\)) & \\ \hline I\({}_{\text{MAT}}\) = (\(\Sigma\)i Cmi \(\times\) IU\({}_{\text{MAT}}\)) + (IU\({}_{\text{TRAN}}\)\(\times\) Cmi) & (4) \\ \hline IUMAT: unit impact per material (MJ; tCO\({}_{2}\)eq; m\({}^{3}\) of water, all per kg of material) & \\ \hline IUTRAN: unit impact of material transport (MJ; tCO\({}_{2}\)eq.; m\({}^{3}\) of water, all per kg of material) & \\ \hline Cmi: construction material i (kg) & \\ \hline \end{tabular}
\end{table} 
Table 1: Equations for the calculation of the embodied energy, carbon footprint, and water footprint of the basic construction elements. The original unit of measurement of each BC (m\({}^{3}\), m\({}^{2}\), meters, tons, thousands of units, etc.) is converted into m\({}^{3}\), so that the density established in support documents, such as the Catalogue of Construction Solutions of the Technical Building Code (IETc, 2010) [57] and the Spanish Technical Building Code [58], can then be translated into kilograms. In some cases, the weight can also be obtained directly from commercial data in supplier catalogs. For the environmental information to be included in the assessment, among the various LCA databases, the Ecoinvent database [59], which is implemented in Simapro and developed by the Swiss Centre for Life Cycle Inventories, is chosen due to its transparency in the development of processes (reports, flowcharts, methodology, etc. ), its consistency, and its references. This database is highlighted because it merges data from several databases of the construction industry [51]. From this database, a series of \"environmental families\" are obtained and handled for each BC and their corresponding impact units according to their similarity.