Emissions accounting for ZEB shoebox office model: - Strategies for optimizing the operational energy supply- Strategies for reducing the embodied carbon from a life cycle perspective
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Buildings consume approximately 40% of the world’s primary energy use and contribute up to 24% of global green house gas emissions. An energy consuming as well as producing building, denoted as zero energy and zero emission building (ZEB), can be seen as a solution in respect to energy efficiency and environmental impact. However, a clear and agreed definition of Zero Emission Building is yet to be achieved, both internationally and in Norway. Nevertheless, national research programmes, such as Centre on Zero Emission Building (ZEB), started to focus on investigating and developing the ZEB concept. The study was part of an ongoing research project "ZEB Shoebox modeling and development of a CO2 accounting method" being conducted in the ZEB centre whose objective is toinvestigate the impact on emissions of different envelope and energy supply system combinations for a simple office building. The focus of the thesis was on the GHGs emissions related to operational and embodied energy of the ZEB Shoebox Office model, using the Norwegian online programme called Klimagassregnskap. Designing a ZEB Shoebox model with reduced energy demand was the initial step for developing the reference building. Starting from this reference case, two scenarios were defined focusing on the operational and embodied energy, respectively. In the first scenario the emissions from different renewable energy supply options were calculated with different methods (Klimagassregnskap among the others) while in the second, the embodied emission accounting for various structural solutions was performed using Klimagassregnskap. The results of the first scenario indicated that the energy generation on the building footprint (solar thermal and PV) is the optimal energy supply in terms of GHGs emissions and delivered energy. While the findings of the second scenario showed that the service life of the materials in the envelope and internal partitions has a higher impact on the embodied emission than the choice of structural materials. Moreover, the results showed that Klimagassregnskap suffers from a lack of transparency in emissions calculation and in the inputs used for defining the emission factors. Therefore further improvements are needed for a more accurate assessment of the future ZEB buildings environmental impact.