Investigation of non-bearing exterior walls in public housing by life cycle assessment (LCA) method, Düzce example

In the world, 40% of energy consumption takes place in industry, 31% in buildings, 19% in transport, 5% in agriculture and 5% in other areas. Approximately 40% of energy losses in buildings are realised in external walls. In the construction sector, it is important to use resources efficiently in the production, use, maintenance and disposal of building elements. In this context, the Life Cycle Assessment (LCA) method has been developed in order to identify and reduce the environmental impacts of products and services. LCA is used to determine the material, energy flow and environmental impacts in the system during the extraction, production, distribution, use and disposal of raw materials in the production of a building material. This study covers the exterior walls of the buildings in the mass housing area with a total of 7000 houses built in Düzce after the earthquakes in 1999. Considering the production, distribution, use and disposal of the building materials in the exterior wall sections of the buildings, analyses were made with the LCA method. Within the scope of this study, a total of 5 exterior wall models were analysed. The exterior wall models analysed are firstly the existing brick wall, brick wall in accordance with TS-825, concrete wall, aerated concrete wall and pumice & briquette concrete wall. These external wall models were evaluated by calculating their thermal transmittance resistance according to U=0,6 for Düzce province located in the second degree day zone in accordance with TS-825 regulation. As a result of the LCA analyses of the exterior wall models, it was determined that the least costly exterior wall section was aerated concrete in accordance with TS-825 and the wall with the highest LCA cost was concrete wall. When "Aerated concrete wall" conforming to TS-825 is taken as a reference, it is understood that the LCA cost of the pumice-brick wall is approximately 22% more, the brick wall conforming to TS-825 is approximately 24% more and the concrete wall conforming to TS-825 is approximately 44% more. However, it is understood that the LCA cost of the existing brick wall that does not comply with TS-825 is approximately 2% more. In terms of carbon cost, the highest cost was found to be in the concrete wall. It was determined that there are statistically significant differences (sig. 0.00) between the LCA costs and carbon costs of the exterior wall models at 95% confidence interval. As a result of the analyses and evaluations, it is understood that the most suitable wall model in terms of total LCA cost in permanent residences in Düzce province is Aerated concrete wall. However, it is evaluated that the initial construction costs of the buildings should also be analysed together with the LCA cost analyses.