A human thermal model for improved thermal comfort

Energy efficient very low-energy houses, passive houses and nearly zeroenergy houses have a significantly lower heating power demand than traditional buildings. Therefore, the typical design and dimensioning criteria of conventional structural and building service system concepts need to be verified to avoid problems concerning the thermal sensation and comfort of the building users. Fanger’s PMV-method is traditionally used for estimating thermal sensation and comfort. The PMV method does not take into account the human thermoregulatory system, therefore it progressively over-estimates the mean perceived warmth of warmer environments and the coolness of cooler environments. Human thermal models represent the human body from a thermokinetic point of view and they have been used for modelling the thermoregulation system. This thesis presents the first approach, where a human thermal model is implemented in a building simulation environment: the Human Thermal Model (HTM). HTM can be used for predicting thermal behaviour of the human body under both steady-state and transient indoor environment conditions. It is based on true anatomy and physiology of the human body. The connection with the building simulation environment enables defining the external boundary conditions such as surface temperatures and radiation heat transfer more accurately than with the previous human thermal models. HTM tissue heat transfer, thermal sensation and thermal comfort calculation has been successfully validated under various steady-state and transient indoor environment boundary conditions comparing the simulation results to measurements made with real human beings. The simulated thermal sensations with the HTM method showed a better correlation with measured values than the Fanger’s PMV method. According to the simulation results, the operative temperature, metabolic rate and clothing are the most dominant boundary conditions for the human thermal sensation and comfort. HTM can be used for estimating the effects of alternative building structures, as well as building service systems, on occupants under different conditions more accurately and easily than before. The realistic thermal comfort of the user can be used as a design parameter for designing better thermal environments in new and renovated buildings.