Occupant behaviour and energy conservation of high-rise residential buildings in Hong Kong

Abstract

Buildings account for 30% of the global energy use and occupant behaviour has a significant impact on building energy use. High-rise buildings have become an irreversible trend with the urban population growth, especially in subtropical cities. However, it remains unclear about occupant behaviours in high-rise buildings in the hot-humid zone, the motivation for energy saving behaviours, and the underlying mechanism of occupant-centric energy saving measures. This research aims to examine the stochastic, diverse and dynamic occupant behaviours in high-rise residential buildings in a typical subtropical city, Hong Kong, and to explore the feasibility of occupant-centric energy conservation from an interdisciplinary and systematic perspective. The examination was conducted from the perspective of both building sciences and social sciences utilising mixed methods. First, key triggers of adaptive behaviours were identified, and pertinent representatives of diverse behaviour modes were composed based on the empirical data obtained from two high-rise case buildings and more than two thousand participants by questionnaire surveys, interviews, and in-situ monitoring activities. Then, a social psychological model was established by expanding the Theory of Planned Behaviour to explain occupants’ energy saving behaviours and behavioural intentions. The expanded model was tested by structural equation modelling techniques. Subsequently, an “Active, Moderate, and Cautious (AMC)” hierarchy was proposed for the segmentation of occupants and their behaviours from multidisciplinary perspectives, including occupants’ demand for comfort, preferences for certain behaviour, and energy dependence. The newly proposed hierarchy was validated using building simulation techniques. Finally, a “material, behaviour, and cognition” framework considering the dynamics of occupant behaviour was established in reference to the Social Practice Theory, and an integrated evaluation system for occupant-centric energy saving measures was proposed accordingly.

The first finding is that behaviour modes are largely varied among occupants, which is the most important explainer of energy use discrepancy. Energy bill difference also exists between residents living at higher and lower floors in high-rise residential buildings during cooling seasons. Second, an individual’s energy saving behaviour is determined by behavioural intention, which is significantly impacted by personal moral norm, perceived behavioural control, and attitude. Gender differences and the moderation effect of thermal sensation should not be ignored to ensure the successful practice of energy saving behaviours. Third, foreseeable energy savings can be achieved by appropriately guiding user behaviours, but many uncertainties remain. It is necessary to learn about the target population to design an appropriate intervention strategy.

The findings of this research extend the existing body of knowledge about the diversity and dynamics of occupant behaviour with a robust theoretical basis and fresh data. This research has provided an explanatory social psychological model, a functional hierarchical classification of occupants and their behaviours, together with a feasible roadmap to track behaviour change. It brings to light the associations between energy savings, occupant behaviours, and interventions. The findings will help stakeholders to have a better understanding of occupant behaviour and behavioural energy efficiency. The interdisciplinary methodology in this research is also expected to inspire future studies.