Occupant behavioural freedom in building energy use

Abstract

Building occupant behaviour is known to be an important factor that drives building energy use and the associated carbon emissions. A substantial body of work has investigated occupant behaviour and the underlying drivers. Yet it is generally known that some buildings allow only minimal behavioural intervention, such as on/off control of lights. Other buildings allow a much higher degree of intervention, for instance through setting of temperature set-points, ventilation fan speed control, the opening/closing of windows, and blind operation. This paper explores the constraints that buildings pose to the freedom of occupants to vary their behaviour and attempts to quantify these building-specific constraints. It reviews the literature on occupant behaviour with a focus on constraints and degrees of freedom that these occupants are allowed. The concept of “occupant behavioural freedom” (OBF) is introduced to capture and quantify these constraints. Case studies are presented to show the application of the concept to real buildings, and to explore how the available occupant freedom relates to actually observed behaviour. Residential cases show a high occupant behavioural freedom, in the order of 95 %. An industrial case has a significantly lower freedom, in the order of 25 % only. At the same time, empirical data show that further constraints limit how much of this freedom can actually be used to save energy: only around 25 % in the residential case, to virtually nothing in the industrial case.