Personalized heating control systems to improve thermal comfort and reduce energy consumption

In recent years, personalized indoor environment conditioning or cooling has received a lot of research attention. Many systems have been designed that can maintain ambient temperatures that are 4 to 5 K higher or lower than temperatures recommended by current indoor standards. Personalized conditioning also allows reduction in energy consumption due to an increased cooling setpoint, a decreased heating setpoint, and a decreased ventilation rate of the background system.

For his PhD research, Michal Veselý looked at personalized heating, which has received considerably less attention than personalized cooling. He focused on three aspects of personalized heating: a comparison of  personalized heaters and their impact on thermal comfort and physiology, the feasibility of an automated control of personalized heating in comparison with user interaction, and energy saving potential of personalized heating in relation to the building characteristics.

Heating test

Vesely and his colleagues designed an experiment to examine two aspects of personalized heating – effectiveness of different heaters and impact of different control modes. His personalized heating system consisted of a heated chair, a heated desk mat, and a heated floor mat, and the setup was tested with 13 test subjects in a climate chamber under an operative temperature of 18 °C.

The heaters were tested separately and in combination with a user-controlled approach. Furthermore, the complete system was tested with fixed setting and automatic control using hand skin temperature as a control signal. The heated chair and the heated desk mat, as well as the complete system significantly improved thermal comfort, while the heated chair was found to the most effective heater. The automatic control mode could provide the same level of thermal comfort as user control.

Energy consumption

A relation between mitigated cold discomfort and the energy consumption was then derived by Vesely for the personalized heating system tested in a human subject experiment. Afterwards, a medium sized office building was simulated in four different locations with three different building envelope characteristics corresponding to construction periods from 1970 to 2012. The heating setpoint was reduced, while the cold discomfort was mitigated by a personalized heating composed of a heated chair, a heated floor mat, and a heated desk. The results show that the total thermal energy demand can be considerably reduced by applying personalized heating.

Case studies

After this study, Vesely then considered two case studies that focused on evaluating the feasibility of using the hand skin temperature as a tracer of thermal comfort for personalized heating. In an office environment, the skin temperature has to be measured in a contact-less manner to avoid any possible disturbance of the workers. This leads to a necessity for tracking of their hand movements.

The first presented case study focused on tracking the finger movement in a high-resolution infrared image, while the second one presented a low-cost infrared array, which could be then combined with movement tracking in visible spectrum.

State-of-the-art

Vesely’s work comprises of research on personalized heating in three main subtopics – a comparison of different heaters, their process control, and energy performance. The comparison of different heaters contributes to a state-of-the-art in his research field, and identifies the feasible methods of personalized heating. It has also been demonstrated that an automatic control based for human physiology has the potential to complement or even substitute for user interaction. Finally, the energy performance and application potential were analysed on a simulation case study.

Title of PhD thesis: Personalized Heating Control Systems to improve thermal comfort and reduce energy consumption. Supervisors: Wim Zeiler and Rick Kramer.