Research On Integrated Thermal Inertia Of Buildings

Energy saving has been paid more and more attention by the country because of the crisis of energy. Building energy consumption occupies a proportion of about 35% of total energy consumption and HVAC energy consumption occupies a proportion of about 65% of building energy consumption. As a typical type in HVAC syst em, energy waste problem exists in common in centralized heating systems owing to present conditions limit and centralized heating systems have a great potential of energy saving. Since there are no advanced controlling methods for many centralized heating systems, the adjustments are made manually and entirely depend on experience according to weather without considering the effect of other factors. Therefore, result of the adjustments is not satisfying. Not only weather but also integrated thermal inertia of pipe network and buildings should be taken into account during the adjusting process.Research of this paper focuses on a typical kind of resident buildings without any energy-saving measures in Tianjin University -students'dormitory(heating with radiator only). This kind of building and similar ones take up about 85% of the buildings in heating area taken charge by Liulitai heat exchange station of the centralized heating system. Research on the integrated thermal inertia of this kind of buildings can significantly supply theoretical instructions to adjustments of this heat exchange station, which can improve heating quality and realize energy saving.The performance characteristics of inside surface temperature of outside walls and indoor temperature were simulated,tested and analyzed with methods of theoretical calculation,simulation in EnergyPlus and experiment test. The temperatures of inside surface of outside walls and indoor air temperatures during heating period corresponding to occasion without any heating equipments,occasion with water heaters and occasion with radiators were simulated and compared. All influence factors on integrated thermal inertia of buildings were analyzed and generalized. Different characteristics of integrated thermal inertia of buildings were studied by comparing and analyzing the experiment test results of quantity of heat,inside surface temperatures of outside walls,indoor air temperatures and outdoor air temperatures of rooms with different facing directions. The results of the simulations and experiment tests can be explained more rationally by the calculation and analysis of outdoor integrated temperature. Finally, the characteristics of integrated thermal inertia of the dormitory were summarized in terms of time delay and attenuation by the general comparison and analysis of the simulation and experiment results.The research results indicates that the integrated thermal inertia of buildings is related to the envelope materials of buildings,shape coefficients,facing directions,proportions between outside windows and walls and other factors. The time delay between the inside surface temperatures of outside walls and the outdoor air temperatures is about 10 hours, while there is not a obvious time delay in indoor air temperatures due to the influence of the solar radiation through windows in south-facing rooms. The influence of the heat storage in envelope on indoor air temperature is not obvious in south-facing rooms and the indoor air temperatures almost change in correspondence with the outdoor temperatures; However, the influence of the heat storage in envelope on indoor air temperature of north-facing rooms is relatively obvious and the time delay between indoor air temperatures and outdoor air temperatures is about 2 hours.