# Improving Sustainability of Steel Roofs: Life Cycle Assessment of a Case Study Roof
## 4 Discussion and Recommendations
### Recommendation for Improving the Sustainability of Steel Roofing Products  
The study conducted the LCA of steel roofing products from the production to the EOL stages, including the potential benefits after the life stages (module D). The LCA study was intended to analyse each process during the steel roof product's life cycle, which in this assessment is the long run roofing profile with five ribs. By considering each process that occurred during the product's life cycle, identifying the most significant process in terms of the environmental impacts produced was possible. Therefore, it enabled the study to identify key processes during the life of steel roofing products that need improvement in environmental performance. 1. There was a large part of the environmental impact from the steel roof product's raw materials and manufacturing processes. The processes were identified as the hotspots of the steel roofing product by having more than 50% environmental impact across all indicators. In addition, when including the ancillary items, the steel roofing production processes also had the biggest environmental impact, accounting for more than 80% of the total impact in most categories. Therefore, this highlights the potential room for improvement in the steel roofing product's environmental performance by reducing the effects of the product's manufacturing processes. Optimising the steel roof design can be one of the solutions for reducing the impacts of the manufacturing processes. Reducing the weight of steel used can potentially reduce the amount of raw material and also the amount of energy used during the manufacturing process. 2. Although the roll forming process had lower environmental impacts than others, identifying the highest impacts from the components during the process was performed. The machine used in the study to press and cut the steel coil into the final long run roofing profile with five ribs had the largest impact on the environment, which is 69% of the total impacts, in comparison with other activities in the processes. One of the other contributing factors was the direct electricity consumption used by the machine. According to 2019 national electricity supply data [76], most of the electricity supply in New Zealand is primarily from renewable energy sources. However, 17.5% of the energy generated is from burning fossil fuels [76]. Thus, improving renewable energy production, such as using photovoltaic (PV) panels in manufacturing sites, can reduce the effects of fossil fuel consumption during the roll forming process. 3. It was found that the recycling of steel products at the EOL stages had a significant positive influence on the environmental impacts for all impact categories. There was a significant recovery of the life cycle impacts after the recycling process, which could reduce the impact values by up to 45% of the total impacts in GWP, POCP, and ADP fossil indicators. Therefore, it highlights the importance of the reuse and recycling processes of the steel roofing product in improving its environmental performance. In addition, some recommendations are made to improve the accuracy of steel roof environmental effects in simple life cycle assessments, which would eventually assist in reducing overall emissions from steel roofing. \begin{table}
\begin{tabular}{c c} \hline \hline
**Impact Category** & **Percentage Increase of Roofing Only** \\  & **Impacts** \\ \hline Global Warming Potential & 9\% \\ Ozone Depletion & 14\% \\ Acidification & 24\% \\ Eutrophication & 40\% \\ Photochemical Ozone Creation & 3\% \\ Abiotic Depletion—Elements & 14\% \\ Abiotic Depletion—Fossil & 27\% \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Recommended percentage increase in environmental impacts from roofing only to include ancillary items. LCA should consider the source of the steel coil used in roofing. When the final guidance for completing a simple LCA is released, it should include data to consider all major brands of steel coil used for roofing.