Jcg Jacob Verhaart

Personal heating: effectiveness and energy use

Buildings use approximately 40% of primary energy with most energy expended on the provision of a comfortable indoor climate. An extended range of indoor temperatures can significantly reduce the energy load. However, lower temperature set points for heating can cause thermal discomfort. Giving building occupants the option to warm themselves (e.g. a local source at their desk or workstation) can mitigate this discomfort by the provision of a personalized conditioning system. A model is presented to assess the performance of personalized heating and its impact on the whole building energy load. Researchers, designers and facility managers can use this model to compare performance and analyse energy savings. The total energy use of personalized heating is estimated by scaling its settings to the actual level of discomfort resulting from a lowered heating set point. This model is used to assess seven different personalized heating systems. Assessments reveal that personalized heating brings a remarkable energy-saving potential, while maintaining or even improving individually perceived thermal comfort. Assessments are based on an assumed linear relation between the power and level of increased thermal sensation. Future research in personalized conditioning systems should be directed towards the development of the full characteristics and specific settings.

User interaction patterns of a personal cooling system: A measurement study

Personal cooling systems provide cooling for individual office occupants to maintain thermal comfort at their workplace when cooling is needed. The indoor temperature of the office can be maintained at several degrees higher than is customary in offices today when personal cooling is available, which results in energy saving for office buildings as a whole. To better understand the individual cooling demand of building occupants and develop good control strategies for personal cooling systems, it is necessary to assess the interaction between the user and the personal cooling system. For this purpose, a personal cooling system was tested in a stable, slightly warm environment (27.5°C) in a climate chamber with 11 human subjects. The personal cooling system was controlled by the subject using a simple slider. The interaction of the user with the system was related to comfort level and perceived air quality. The subjects are categorized into groups based on gender, on comfort level, and on whether their comfort improved during the test or not. The results show that comfort level did not directly reflect in a difference in the number of interactions or level of the setting. The largest difference in setting was found between male and female subjects, where females required less cooling.