Indoor climate experience, migration, and thermal comfort expectation in buildings

Abstract

Advances in heating, ventilation and air conditioning (HVAC) technologies have dramatically improved the indoor thermal environment, but attention should be paid on how this would affect building occupants' thermal comfort perception. In this paper, we studied the mutually dependent relationship between indoor climate experience and occupants' comfort expectation. An intriguing experiment was conducted in China where wintertime indoor thermal environments in northern cities (with district heating) are much warmer than in southern region (without district heating). By analyzing the 4411 responses from four college-aged subject groups with different indoor thermal history, two interesting findings emerged. Firstly, people's understandings of thermal comfort change with their indoor thermal experiences. Those permanently live in lower-grade non-neutral thermal environment can achieve similar thermal comfort perception as those who live in long-term comfortable thermal conditions. Secondly, the dynamics of building occupants' thermal comfort adaptation project asymmetric trajectories. It is much quicker for occupants to accept neutral indoor climate than to lower their expectation and adapt to under-conditioned environments. These two phenomena can be well described by the index "demand factor", which can serve as a reference for future thermal comfort study.

A data-driven approach to defining acceptable temperature ranges in buildings

“…al. found that occupants quickly increase their thermal comfort expectations and rarely compromise once raised [38]. Occupants becoming accustomed to, or even demanding, tighter temperature tolerances might explain why tight temperature ranges do not necessarily improve thermal comfort.…”

Nudging the adaptive thermal comfort model

“…However, exploring regional differences in adaptive comfort revealed a potential nudge of the intercept term of the model for naturally ventilated buildings. It stands to reason that, along with climatic drivers and physiological adaptation, there are cultural influences shaping thermal perception of building occupants around the world (Auliciems, 1981;Yao et al, 2009;Schweiker & Wagner, 2015;Luo et al, 2018). The steeper gradient for the Asian subset in Figure 5 suggests occupants of buildings located in Asia are more thermally adaptive than what we saw in the original ASHRAE adaptive comfort standard.…”

“…The overwhelming majority of our time is spent indoors, so it is conceivable that the temperatures we are exposed to inside the built environment exert the more powerful effect on our comfort expectations. Luo et al (2018) showed that indoor exposure can largely shape occupants' expectations of their thermal environment. In their analysis of Database II, reported better predictive capacity of thermal sensation using only indoor air temperature compared to the fully-elaborated heat-balance model (PMV-PPD) requiring six input parameters.…”

Influence of the Improvement in Thermal Expectation Levels with Adaptive Setpoint Temperatures on Energy Consumption

“…In this regard, it is worth stressing that the adaptation capacity of the occupants' thermal comfort usually has asymmetric trajectories [45]. Users more used to the use of HVAC systems will have therefore more difficulties to increase the limit values of the operative temperature than those not using such systems [45]. For this reason, this study analyzed various tolerance ranges in the adaptive thermal comfort model used in setpoint temperatures.…”