Mathias Kimmling

• Individual thermal comfort in buildings, especially in office workplaces, is becoming increasingly important in modern society. While technical devices for user-specific heating are well known and implemented, only a few proven methods for individual cooling of a single person are available, most of which are limited to convective heat transfer. The primary goal of this research was the development of an effective and efficient cooling system for individual building occupants based on longwave radiation exchange. To achieve this, the technological concept of a thermoelectric cooling partition with latent heat storage (Thecla) was developed. The system combines Peltier elements and heat storage based on a phase change material to provide a tempered surface for directional radiative cooling of a person. Thecla has been practically evaluated in the form of real prototypes in hardware tests and human subject studies. In addition, the concept was evaluated theoretically through precise thermodynamic analyses of each individual component and of the overall system. Based on these assessments, an explicit computational model of Thecla was developed, which calculates the thermodynamic behavior and energy balance of the system for varying environmental and operating parameters. Coupled with measured and simulated building energy data, the overall energy efficiency of Thecla in combination with central space cooling systems was assessed. The analysis suggests, that the system concept of the thermoelectric partition is effective for individual user cooling. Thecla provides a perceptible and measurable cooling effect associated with a reduction in the overall thermal sensation. The applied technologies allow cooling operation over relevant periods of time and, through latent heat storage, a temporal shift of cooling loads in buildings. For realistic application scenarios in buildings with central air conditioning, an existing energy-saving potential by using Thecla could be proven and quantified.