<p>This study investigates consumers’ reactions to housing energy labels, which are mandated for inclusion in new real estate advertisements in Japan. By employing an eye-tracking experiment, we collected data on the reaction times and the number of round trips between two areas of interest (AOIs) to identify the most effective design elements for energy labels. Additionally, a panel analysis was conducted to control for individual effects, utilizing both the experimental data and the responses to a follow-up questionnaire. The dependent variables in the panel analysis were the reaction times and number of round trips between the AOIs. The findings reveal that energy labels in real estate advertisements significantly enhance consumers’ understanding of energy-saving standards. Furthermore, the results underscore the critical role of label design. Specifically, positioning reference information on the left side of the label improves clarity. If a property exhibits poor energy-saving performance, emphasizing the deviation from the energy-saving standard proves effective. Moreover, this study suggests that using energy labels is effective regardless of the degree of consumers’ concern about the environment. Given that energy labels raise consumers’ awareness of household energy standards and promote energy-saving behavior, the early implementation of labeling for all properties, whether for sale or rent, is strongly recommended.</p>