Considering the alarming energy demand for cooling and seeking sustainable cooling alternatives to over-reliance on air conditioning, our pre-registered study is the first attempt to apply social norm nudges on two cooling behaviors – lighter clothing and the use of personal cooling devices (PCDs). To examine and compare the effectiveness of a descriptive norm message, an injunctive norm signal from leadership, and the two norms combined, we conducted an online randomized controlled survey experiment among financial employees (n = 743) in Guangdong, China. We measured their behavioral intentions before and after the intervention, and their level of commitment to these behaviors as an alternative outcome. We found that while single-norm conditions did not lead to desirable increases in lighter clothing, the both-norm condition nudged participants toward selecting lighter work clothes and boosted commitment to lighter clothing. Outcomes related to the use of PCDs were not affected by any of the norm conditions. These mixed findings present a cautionary tale for designing social norm interventions in office spaces and highlight the boundaries of their effectiveness in energy-saving behaviors.