Default options have been shown to affect behaviour in a variety of economic choice tasks, including
health care and retirement savings. Less research has tested whether defaults affect behaviour in the
domain of energy efficiency. This study uses data from a randomized controlled experiment in which
the default settings on office thermostats in an OECD office building were manipulated during the
winter heating season, and employees’ chosen thermostat setting observed over a 6 week period.
Using difference-in-differences, panel, and censored regression models (to control for maximum
allowable thermostat settings), we find that a 1°C decrease in the default caused a reduction in the
chosen setting by 0.38°C on average. Sixty-five percent of this effect could be attributed to office
occupant behaviour (p-value=0.044). The difference-in-differences model shows that small decreases
in the default (1°) led to a greater reduction in chosen settings than large decreases (2°). We also find
that office occupants who are more apt to adjust their thermostats prior to the intervention were less
susceptible to the default. We find no evidence that offices with multiple occupants displayed
different patterns in thermostat choices than single-occupant offices. We conclude that this kind of
intervention can increase building-level energy efficiency, and discuss potential explanations and
broader policy implications of our findings.
