Long- or short-term exposure to air pollution would distort human's cognitive function which has aroused widespread concern in interdisciplinary fields. It furtherly seems rational to assume that air pollution may affect energy use in public buildings. However, the overlooks of the potential impacts of air pollution on energy use would result in substantially higher energy saving cost. By matching the real-time energy consumption of public buildings to indoor and outdoor PM2.5, we construct a panel containing 193,226 data items. Based on this, we conduct the first preliminary exploration to try to reveal the impact of PM2.5 on energy use at the building-hourly level. Results show that the increase of energy intensity caused by PM2.5 is subtle, it indeed exists significantly. When indoor PM2.5 is 1 μg/m3, the marginal effect is minimum. After indoor PM2.5 exceeding 1 μg/m3, the marginal effect began to increase and the maximum is 0.3224 when PM2.5 is 1114 μg/m3. However, given the sorting and contrast effect, the practical relationship between indoor PM2.5 and energy use is possible inverted-U shaped. Furtherly, we find long term exposure to outdoor PM2.5 would not make people adapt to air pollution and instead cumulative the impact on energy use. Besides, centralized office could be an economical and feasible measure to achieve energy saving goal. Finally, we propose that it is promising for achieving the synergy between air pollution control and energy consumption reduction.