Do Climate Zones Determine Indoor Temperatures? Evidence from Indoor Temperatures Profiles in Chilean Houses

Climate zoning is widely used to establish building-envelope requirements and estimate residential heating and cooling demand. However, regulatory classifications based primarily on outdoor climatic variables may not adequately represent the diversity of indoor temperature patterns observed under actual building operation. This study assesses the correspondence between regulatory thermal zoning and measured hourly indoor air temperature profiles, using Chile as a case study. Indoor air temperature was monitored at 5 min intervals in the living rooms and bedrooms of 116 occupied dwellings distributed across 14 cities representing eight of Chile’s nine regulatory thermal zones. The measurements were aggregated into hourly profiles and analyzed separately according to room, season, and annual period using k-means clustering. Complementary linear mixed-effects models were used to assess associations between cluster membership and household energy consumption. Two characteristic clusters were identified for each room and analysis period. Their spatial distribution did not exhibit a one-to-one correspondence with the regulatory thermal zoning: geographically distant zones frequently displayed comparable indoor air temperature profiles, whereas dwellings located within some individual zones were assigned to different clusters. The clearest separation between profiles occurred during winter, when the coldest clusters reached mean early-morning air temperatures of approximately 14 °C in both living rooms and bedrooms. The energy models did not identify statistically significant consumption differences between clusters; marginal R2 values for the per-capita models ranged from 0% to 2.2%. These findings do not imply that indoor temperatures are independent of outdoor climatic conditions. Rather, they demonstrate that regulatory climate zoning alone is insufficient to represent the variability of indoor air temperatures observed under occupied residential conditions. Although the available measurements do not support formal assessments of operative temperature, thermal comfort, occupant behavior, or energy poverty, the identified data-driven profiles provide an empirical basis for refining indoor-temperature assumptions, developing more realistic baseline scenarios, and supporting the calibration and validation of residential building energy models across different climatic and regulatory contexts.