Energy-related occupant behaviour in green and non-rated buildings

Occupants are one of the factors impacting the overall energy performance of buildings the most. Green buildings improve the levels of liveability in buildings and their annual energy performance by incorporating sustainable design solutions during the whole life cycle of a building. The operation stage is the most energy-intensive stage of a building because it involves technical systems, equipment, and occupants. The difference between actual energy data and the predicted energy has been identified as a main knowledge gap in the literature. This difference is related to the low maintenance, inefficiencies, and occupants. One of the main gaps of most green certification processes is related to the occupant behaviour (OB). Previous studies mainly focused on investigations of the energy-related OB in office and residential buildings or test bed environments. The present research comprises the study of the energy-related OB in two distinct university buildings with similar characteristics at Western Sydney University (WSU) in Sydney, Australia. One of the buildings is a 6-star building, according to the Australia certification process Green Star, and the other one is an existing non-rated building. The purpose of this study is to determine the direct and/or indirect impacts of occupants on the overall energy use in both buildings as well as how occupants perceive energy and their environmental and economic impacts. Other goals are to determine if the green rating has an impact on the way occupants interact with the building systems and if there is any significant difference between green-rated and non-rated buildings. Therefore, to support this study, a chronological literature review related to the OB and its effect on the energy use was carried out. Subsequently, building simulations were performed for the buildings using actual data and the software tools DesignBuilder and EnergyPlus. The occupants were categorised according to their level of energy use, that is, as saving, real and intensive energy users. Dynamic simulations were performed by varying parameters related to the lighting, plug loads, infiltrations, shading, and AC setpoints. The models were calibrated with actual annual data measured and registered by the university management system. In addition, 100 surveys were delivered to occupants, inquiring about their perception and interactions with heating and cooling, lighting, window/door opening, window blinds, and appliances. The results were obtained from statistical analysis using the software SSPS. Finally, the perceptions of occupants related to the energy use based on the surveys were used as input variables for the dynamic simulations. The actual behaviours and actions of occupants were quantified in terms of the energy use, greenhouse gas emissions, and costs. Furthermore, the correlation between climate and the energy-related OB for green-rated and non-rated buildings was studied in eight different climate zones in Australia. The results show that saving users will spend on average 43% less energy, while intensive users will spend on average 29% more energy, in both buildings, compared with real users. The overall energy use based on the occupant behaviour changes within similar ranges in both buildings and the green rating has no significant impact on the energy-related occupant behaviour. It is not possible to conclude that the occupants of the green building are more energy-efficient than the occupants of the non-rated building. However, the green rating affects occupant's overall satisfaction. The gender and age impact the perception of energy use. Women and the older generation are more tolerant and energy-efficient than men and the younger generation. Finally, this study shows that the green building is being managed inefficiently due to lack of awareness. Despite being classified as green, if the operational conditions of a building are not carefully maintained according to the best practices (rating), a green-rated building will operate within similar ranges as a non-rated building.