Simulating cooling loads for personal environment comfort systems

Standard heating, ventilation, and air-conditioning systems are designed to condition the entire internal volume of the occupied spaces in the buildings. Regardless of how precisely regulated the thermal environment is, the discomfort of studies has pointed out that approximately 62% of occupants remain unsatisfied with their immediate thermal environments. Personal Environment Comfort Systems (PECS) offer the potential to provide thermally acceptable indoors to the occupants with a potential to save energy. The PECS often attempt to target one or multiple body parts to provide heating, cooling, ventilation or a combination of it. This study adopts the Joint Circulatory System (JOS-3), a thermoregulatory model to understand the interplay of various body parts and their ability to reject the body heat relying on the four modes of heat transfer, conduction, convection, radiation and evaporation. It studies the change in the whole-body comfort conditions and physiological responses to the thermal environment at 5°C change in operative air temperature (Top) between 10°C and 40°C. Each Top represents a scenario and a simulation run with 60minutes of exposure time keeping other environmental and personal parameters constant such as physical activity (MET), Clothing insulation (Clo), and relative humidity (%). This study also extends to the estimation of sensible and latent heating and cooling load requirements in varied indoor conditions. The study concludes with multiple observations providing insights, such as convective heat loss of the foot varies between 9.0W to 2.0W between 14°C to 35°C while for the head it is between 2.0W to 1.5W. The radiative heat loss of the foot varies between 17.0W and 3.0W and heads between 3.0W to 0.25W for the same conditions. Such estimation may help design PECS targeting individual body parts to gain higher thermal comfort satisfaction and savings of energy.