Evaluating the performance of building thermal mass control strategies

A tool was developed that allows evaluation of thermal mass control strateg ies using HVAC utility costs as the baseline for comparison. Inverse models are used to represent the behavior of the building, cooling plant, and air distribution system. Inverse models use measured data to "learn" system be havior and provide relatively accurate site-specific performance prediction s. Based on weather and solar inputs, as well as occupancy and internal gai ns schedules and utility rates, the evaluation tool predicts the total HVAC utility cost for a specified control strategy. Intelligent thermal mass co ntrol strategies can then be identified in a simulation environment using t his analysis tool. The evaluation tool was validated using data collected f rom afield site located near Chicago, Illinois. The tool predicted HVAC uti lity costs for a summer month billing period that were within approximately 5% of actual costs. Additional studies were performed to examine the utili ty savings potential for summertime operations at the field site using vari ous thermal mass control strategies. The best strategy resulted in approxim ately a 40% reduction in total cooling costs as compared with night setup c ontrol. Simulation studies were also used to analyze the overall impact of location on the savings potential for use of building thermal mass. Represe ntative utility rates for five locations (Boston, Chicago, Miami, Phoenix, and Seattle) were used along with the models obtained for the field site. S ignificant savings were achieved in all locations except Seattle.