Thermoelectric air conditioning undergarment for personal thermal management and HVAC energy saving

•Lightweight thermoregulatory garment for thermal comfort and HVAC energy saving.•Expanding indoor neutral band by personal thermoelectric air cooling or heating.•Different designs of hierarchical branched tubing system for air distribution.•Optimized tubing design for energy and volume efficiency inspired by Murray’s law.•Quantification of personal cooling/heating power required for neutral band expansion. Personal thermal management systems (PTMS) are highly desirable for improving individual thermal comfort and reducing indoor HVAC energy consumption. Although there have been many attempts in developing PTMS, existing PTMS are generally bulky, heavy or immobile. Besides, previous analysis on additional personal cooling and heating power required for maintaining thermal comfort in changing environments did not consider the individual difference in metabolism and the variability of comfort skin temperature with environmental conditions. Here, we report on the development of a novel lightweight (