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UBC Theses and Dissertations

Lifecycle based energy assessment of green roofs and walls Feng, Haibo


The building and construction industry accounts for 30-40% of natural resource and energy consumption on earth, and it also contributes to 30% of greenhouse gas emissions. Therefore, it is a major cause of environmental pollution. The environmental impact of buildings could be considerably reduced through sustainable building practices. Covering a building envelope with green vegetation, such as a green roof and living walls, is one of these sustainable construction practices. This study conducted a lifecycle assessment to evaluate the sustainability of living walls in air cleaning and energy savings. Furthermore, the energy saving performance of green vegetation in different parameters was analyzed in normal commercial buildings and green buildings. As the first step, a comparative lifecycle assessment of three living wall systems was conducted. Chemical emissions and energy requirements of the living wall materials were evaluated in the full lifecycle, and compared with the chemical absorption and energy savings of operational living walls. The results demonstrated that the felt layer system is not environmentally sustainable in air cleaning and energy saving compared to the indirect greening system and modular panel system. In the next step, a building energy simulation was executed to assess the energy saving performance of green vegetation in commercial buildings. Parameters such as greening scenario, building type, building vintage, weather condition, and building orientation were considered in the simulation. The energy simulation results demonstrated that all these parameters have a significant influence on the energy saving performance of green vegetation. Furthermore, the energy saving performance of green vegetation was analyzed in a LEED certified green building. The simulation model was validated with the actual operational energy consumption. The simulation model was used to analyze the energy saving performance of green vegetation under different scenarios. The results showed that the green vegetation could significantly reduce the negative heat transfer through the building façade in a summer and winter typical week. Moreover, the green vegetation not only delayed the start time of heat gain but also extended the period of heat loss in the summer. Based on the above analysis, a green vegetation application guideline was developed to ensure the installation of green vegetation could achieve the best energy saving benefits with the least environmental impact.

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Attribution-NonCommercial-NoDerivatives 4.0 International