Thermal Perception and Energy Efficiency Using Heat Spatial Integration

Thermal displays hold promise for supporting thermal comfort in products involving steady contact such as smart office chairs, electric vehicle seats, and heated toilet seats. However, conventional thermal conduction methods have practical limitations due to their large device size and high energy consumption. This study leveraged a spatial integration effect similar to thermal referral or heat phantom sensation, hereafter referred to as the heat spatial integration illusion (h-SI), which induces the perception of warmth between discrete stimulus points, demonstrating its potential for achieving superior perceptual characteristics and energy efficiency. Psychophysical experiments conducted at near-human body temperature ($37^\circ \text{C}$) on the arm revealed that the warmth perceived by h-SI is controlled by the temperature of the central stimulus and no significant effect of stimulus distance was detected between 60 mm and 100 mm under the tested conditions. Furthermore, the h-SI design demonstrated a model-based estimate of power reduction of 6%- 13% under steady-state conditions across central stimuli of 27, 30, and $33^\circ \text{C}$, compared to presenting the same temperature with a single element. These findings provide crucial foundational guidelines for realizing energy-efficient thermal displays.