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Zhang's Local Thermal Comfort Prediction

Download the Zhang thesis:

"Human Thermal Sensation and Comfort in Transient and Non-Uniform Thermal Environments"

Zhang's comfort model is based on 109 climate chamber test cases at the University of California (Berkeley). Humans under dynamic and inhomogeneous thermal boundary conditions had been tested. Many years of research work led to mathematical models that first derive the actual state of thermal sensation (local/global) and then in a second step predict the local thermal comfort index as a function of the thermal sensation levels. Hui Zhang's model was presented in her PhD thesis in 2003. Thermal sensation and comfort can be predicted for 19 different body parts (e.g. back). Individual parameters for those body parts are presented in huge tables fed by measurements and correlations.

Essential input of the Zhang model are (given) skin and core temperatures. Those values might result from measurements or simulations. Because of its well validated local thermal responses a combination of Fiala's manikin with Zhang's local thermal comfort model is obvious.

The figure shows simulated results for the thermal comfort index at the human's back resulting from variants of seat heating systems. Different heat load functions applied in the contact zone between the manikins back and the seat have been compared. The essential input data for the comfort model are simulated skin temperatures and their derivations in time (dT/dt) in the contact zone. Final aim of local comfort predictions for seat heating systems is to identify optimized functions for the heat load to be applied in the contact zone.

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