Analysis of low carbon solution alternatives for vertical envelopes in the energy retrofitting of existing housing blocks

Global climate change is one of the greatest challenges facing humanity today. Emissions containing gases that contribute to the greenhouse effect, arising as a result of human activities (anthropogenic), are identified as the most significant factor accelerating the increase in global temperature. Scientists studying on climate change believe that if efforts are made to limit the continuously rising global temperature since the Industrial Revolution and work towards cooling the Earth before it reaches its peak, the adverse effects of climate change can be mitigated. However, energy, which is crucial for the continuity of daily life, holds primary importance for countries. Especially in the last decade, the global concern about energy supply security has prompted many developed and developing countries to take significant measures by restricting energy consumption. In line with these concepts, the primary aim of the doctoral thesis is to propose a model for a bio-based building envelope that will enhance the energy efficiency of our country's existing housing stock. Proposed envelope models have been developed using building materials with low environmental impact, minimal CO2eq. emissions during production, and the ability to store carbon within their structure. Within the scope of the study, the proposed envelope models have a high thermal transmittance coefficient (U value) and have been applied to the vertical envelope of the existing residential structure examined in the field study. This not only ensured the reduction of carbon emissions solely from operational energy but also resulted in the atmospheric carbon storage within the structure of the existing residential building. In the study, three different methods were applied, including the synthesis of international literature to obtain the embodied carbon value from building materials, the carbon value from energy sources used to provide comfort conditions throughout the service life of the building, and the design of proposed envelope models. The existing residential building without energy retrofit has a calculated embodied carbon value of 97.96 tCO2eq. for the reinforced concrete structural component, 26.46 tCO2eq. for the vertical envelope component, and 8.695 tCO2eq. for the annual usage carbon value from natural gas energy used for heating purposes. As part of the research, the developed EnP-1 proposal embodied carbon value of -27.67 tCO2eq. achieved a 22.08% reduction in energy usage and emissions, the EnP-2 proposal embodied carbon value of -23.67 tCO2eq. achieved a 23.92% reduction, the EnP-3 proposal embodied carbon value of -16.84 tCO2eq. achieved a 23.80% reduction, the EnP-4 proposal embodied carbon value of -19.05 tCO2eq. achieved a 24.82% reduction, and the EnP-5 proposal embodied carbon value of -20.66 tCO2eq. achieved a 22.08% reduction in energy usage and emissions, providing energy efficiency. The doctoral analysis approach, conducted with an energy retrofitting perspective, has concluded that considering our country's existing housing stock, which amounts to millions of square meters, there is significant potential in mitigating the adverse effects of climate change.