Do green nudges affect "green curtains"? : Results from a field experiment in Japan

In Japan, households are required to save more electricity in response to electricity supply shortages after the Great East Japan Earthquake and meet the 66% greenhouse gas reduction target in the residential sector under the Paris Agreement. This study examines the effects of providing information to promote the implementation of green curtains, a summer electricity-saving behavior at home, using a randomized controlled trial for residents in Japan. Green curtains are made by growing annual vines, like curtains on a net stretched across a window or wall, and have the effect of reducing room temperature by providing shade. Based on their characteristics, being visible to others and a low implementation rate, we examine the effects of the perceptions and cognitions of the implementation of green curtains in the city (subjective descriptive norm) and the information provided on the trends in green curtain implementation in neighboring districts (objective descriptive norm) on the respondents' willingness to implement. The results show that subjective descriptive norms influence the willingness to implement. Further, the information about neighboring districts with slightly higher green curtain implementation rates is more effective than information about neighboring districts with significantly higher rates. This examination of the comprehensive influence of descriptive norms and the effect of the dynamic and relatively comparative forms of providing descriptive norm information have implications for studies in other fields on promoting prosocial behaviors visible to others and with low implementation rates.