# A Case Study on Integrating an Eco-Design Tool into the Construction Decision-Making Process
## 3 Results and Discussion
### Case Study: Comparison of Window Frame Solutions
As can be observed, wood and PVC windows are the best performing solutions in a similar number of impact categories (seven and six, respectively), whereas aluminum window frames only presented the best performance in three impact categories, namely acidification (AP), abiotic depletion potential--non-fossil resources (APDE), and use of secondary material (MS). The eco-design tool also provides information regarding possible output flows for the different window frame solutions at the end of life. Table 7 shows that all the solutions examined can be landfilled or recycled at the end of life, but only wooden frames can be used in energy recovery processes. This information is particularly relevant when analyzed in the regional context of a specific construction project for considering the availability of waste management facilities and recycling centers in their vicinity, thus minimizing transport-related environmental impacts and costs at the end of life. In addition to the environmental assessment, the eco-design tool also provides an economic assessment. The economic profile of different window frame solutions was examined in this case study by sourcing financial information from the CYPE Cost Estimator. The total acquisition cost of each solution was determined by multiplying the number of units by the unit cost (Table 8). Maintenance frequency and cost per maintenance action were also collected from the CYPE Cost Estimator and, along with the estimated service life retrieved from the EPD, used to estimate the life cycle maintenance cost (EUR) of each frame solution (Table 9). \begin{table}
\begin{tabular}{l c} \hline \hline
**Parameters** & **Best Performing Solution** \\ \hline Global environmental impact & PVC \\ Global consumption of renewable resources & Wood \\ Global consumption of non-renewable resources & Wood \\ GWP (kg CO\({}_{2}\) equiv.) & PVC \\ ODP (kg CFC 11 equiv.) & PVC \\ AP (kg SO\({}_{2}\) equiv.) & Aluminium \\ EP (kg (PO\({}_{4}\))\({}^{3-}\) equiv.) & PVC \\ POCP (kg C\({}_{2}\)H\({}_{4}\) equiv.) & PVC \\ ADPE (kg Sb equiv.) & Aluminium \\ ADPF (MJ, N.C.V) & Wood \\ TRR (MJ, N.C.V) & Wood \\ TRNR (MJ, N.C.V) & Wood \\ MS (kg) & Aluminium \\ CSR (MJ, N.C.V) & Wood \\ CSNR (MJ, N.C.V) & PVC \\ Use of net fresh water (m\({}^{3}\)) & PVC \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Performance analysis of window frame solutions by impact category. \begin{table}
\begin{tabular}{l c c c} \hline \hline
**Parameters** & \multicolumn{3}{c}{**Case: Window Frame Material**} \\ \hline Code & A11 & A22 & A33 \\ Material/solution & PVC & Aluminium & Wood \\ Reuse & - & - & - \\ Repair & - & - & - \\ Recycle & X & X & X \\ Energy recovery & - & - & X \\ Landfill & X & X & X \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Prospective end-of-life valorization strategies. A graphic representation of the cost structure is generated by the tool for easy interpretation, as shown in Figure 4. The results of the case study under analysis show that PVC window frames present the lowest acquisition cost (EUR 51,016.74) and maintenance cost (EUR 13,775.94), representing an average total cost per year of EUR 2159.76 over the 30-year service life. Wooden window frames were found the least economically attractive option, with the highest acquisition (EUR 79,554.87) and maintenance costs (EUR 59,664.18), representing an average annual investment of EUR 4640.64. The economic results contrast with the environmental analysis, where wooden window frames were found to be the best-performing solution in the majority of the environmental indicators analyzed. Therefore, it is clear that decision-making in this and other analyses can heavily rely on the relative importance that designers will attribute to environmental and economic performance. The new version of the tool includes a final overall assessment covering the environmental and economic dimensions, allowing the user to introduce weighting factors that reflect their relative importance.