Life cycle assessment of retrofitting process for a district

In the thesis, a case study area was examined based on energy consumption and environmental impact during its life time via life cycle assessment (LCA) methodology. There are 79 residential buildings that share similar structure in the area; hence, one of them was selected as reference that the investigated building results were used for whole district. The building was built at the end of 1980s. Detailed energy performance analyzes were performed; besides, the energy efficiency retrofitting strategies were defined based on these energy models. These retrofitting strategies were applied to the building to improve energy performance, decrease released greenhouse gases and increase renewable energy source percentage in overall in 2015. In the analysis, the building life time was estimated 75 years. The first 25 years were considered with baseline conditions, and the next 50 years were considered with retrofitted conditions. The aim is investigating a residential area based on its energy consumption and environmental impact during its life time from cradle-to-grave via LCA methodology. For this purpose, ISO 14040 and EN 15978 standard were used to develop the methodology. ISO 14040 defines general methodology of LCA; besides, EN 15978 specializes it based on building application. Also, EN 15978 methodology was created based on ISO 14040. Therefore, both standard were combined and used for the thesis methodology. Two scenarios were defined in the thesis. The first one is called as baseline scenario. In this scenario, beginning situation of the building was examined during 75 years from 1990 to 2065. The second scenario is called as retrofitted scenario that investigated building from 1990 to 2065. Nevertheless, retrofitted scenario was divided into two part. The first part is between 1990 and 2015 (25 years); besides, the second part is between 2015 and 2065 (50 years). Hence, the first part was examined based on beginning condition of the building, and the second part was examined based on retrofitted conditions. The building life time was divided into 3 stages as product, use and end of life stage in both scenario based on EN 15978 methodology. The building was examined as a whole with materials that were used, energy consumption, transportation and end of life steps. It is means that system boundaries of the thesis was defined as cradle-to-grave from raw materials extraction to disposal in the thesis. Already developed BIM and energy performance model of the buildings were used to calculate the amount of materials that were used in the buildings and energy consumption. In addition, two indicators were defined to demonstrate the results of LCA. These are called as cumulative energy demand (CED) and global warming potential (GWP). The reason for this selection is related with aim of the thesis. Energy consumption of the building and released greenhouse gases from the building were presented clearly by helps of defined indicators. The results were obtained according to defined indicators after all input and output were collected based on defined system boundaries, the developed model was run. Total CED results of baseline scenario is 23,718,772 MJ/75years. Contribution from stages based on percentage is 5% from product stage, 94% from use stage and 1% from end of life stage. Total GWP results of baseline scenario is 2,216,050 kgCO2eq./75years. Contribution from stages based on percentage is 5% from product stage, 83% from use stage and 12% from end of life stage. After baseline scenario results were obtained, retrofitted scenario results were also gotten. Overall CED of retrofitted scenario is 14,036,986 MJ/75years; besides, contribution from use stage is 82%, from product stage is 18% and from end of life stage is less than 1% for CED indicators. Overall GWP of retrofitted scenario is 1,325,967 kgCO2eq./75years; besides, contribution from use stage is 66%, from end of life stage is 20% and from production stage is 14% for GWP indicators. After all results were obtained for both scenario, a comparison was made to show retrofitting strategies impact. Thus, CED of the buildings decreased 41% with helps of retrofitting during building life time. The reduce rate for GWP is 40% in retrofitted scenario. The results of the thesis show overall CED and GWP of the building; also, the results demonstrate all phases of the building from manufacturing materials that were used to disposing of all wastes from the buildings. Also, stages of building life time were analyzed individually to demonstrate their impact on total. As it mentioned before, the building was retrofitted during its usage time. These retrofitting strategies also were investigated in retrofitted scenario. Thus, the importance and impact of retrofitting was demonstrated in the thesis. Based on the results, these kind of strategies can be used to reach energy efficient and more environmentally districts or cities.