Standards and certification programmes support the design of energy-efficient buildings during the design, construction and commissioning stages. However, they often only provide performance expectations before occupancy, generating uncertainty over the actual energy consumption of a building when in use. In fact, low- or zero-carbon buildings have been found to consume more energy than what was predicted by the energy performance rating. Now, Jesus Lizana and team at University of Oxford use a post-occupancy evaluation and intervention protocol to analyse the energy usage and patterns of building occupants and assess the effectiveness of energy management and retrofitting interventions.
The researchers feed into an energy model the results of surveys of occupancy patterns and occupant behaviours along with physical measurement of the building performance to obtain the actual energy usage in a building. The model is then used to analyse the energy, environmental and economic impact of different energy saving interventions. Lizana and colleagues test their approach on a university building in the United Kingdom: they show that energy is wasted on lighting and hot water when the building is unoccupied, overheating in winter, and powering high-consumption appliances (for example, information and communication technologies devices) when not in use. They conclude that energy consumption and carbon emissions can be reduced by over 20% with more efficient energy management of the university building. The researchers suggest that the low-carbon building sector should pay particular attention to the energy demand associated with information and communication technologies when the buildings are unoccupied.
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