Impact of renewable energy technologies on the embodied and operational GHG emissions of a nearly zero energy building

Abstract

The renewable energy solutions are being actively applied to achieve nearly and net zero energy buildings, however very few studies have reported the environmental impact of applied renewable energy sources (RES) on a net zero energy building from the perspective of both embodied and operational greenhouse gas emissions (GHG). As the energy performance of buildings improves, the significance of embodied energy and embodied greenhouse gases increases when compared to the operational impacts. These trends can become more important when the technology for net zero energy and off-grid buildings is being advanced especially when necessitating use of energy storage (batteries).The aim of this study is to advance new knowledge on the impact of local renewable energy solutions on the GHGs of nearly zero energy buildings by considering both operational and embodied impacts. This study presents the case study of a net zero residential building and evaluates three main cases of annual net zero electricity (Case 1), off-grid electricity (Case 2) and 100% solar thermal heat (Case 3) and in total presenting six variations of building integrated RES technologies. The results indicate that the embodied GHG impacts are responsible for two thirds of GHG impacts which is opposite when compared to an nearly zero energy building that is connected to the grid and district heat network (BAU case). When RES technologies are integrated with the building and electricity is produced from renewable sources the ‘Annually net zero electricity’ case produces almost 40% less GHG emissions when compared to the ‘BAU’ case. For the ‘off grid electricity’ case using Li-ion batteries for seasonal energy storage, resulted in the highest embodied GHG emissions due to immature technology.