Heating system performance and thermal mass evaluation of a former military building in mid-Sweden

Abstract: The concern about global warming is gaining momentum. So, many initiatives, such as the Green European pact, which aims to reach to zero greenhouses emissions in 2050, are emerging to halt it. The aim of this study is to evaluate the energy usage, thermal mass and thermal comfort of a past-military building, now part of Gävle’s University Campus. For this purpose, changes in the heating schedule and location of the building, have been made. The results are based on theorical knowledge and computer simulations using IDA-ICE software. For the modeling of the building, a large number of parameters have been taken into consideration, such as climate values, the walls, windows and roof materials, room occupancy, etc. The results have proven that the current heating schedule of the university (24h working) is the most suitable schedule showing the best results on peak power demand and thermal comfort. Compared to constant heating regulation, turning off heating completely during weekends resulted in 10% energy saving, but 369% higher peaking power and discomfort increasing from 18 to 21 Predicted Percentage Dissatisfied (PPD). Same constant heating regulation compared with 8:00 to 18:00 heating regulation shows 18.7% energy saving, but 451% higher peaking power and discomfort increasing from 18 to 36 Predicted Percentage Dissatisfied (PPD), with the greatest discomfort feeling between 8:00 to 9:00. Finally, when comparing the current heating schedule with one on where the heating is shut off on the DH peak moments, results show 3% energy saving, but 152% higher peaking power and discomfort increasing from 18 to 27 PPD. Regarding thermal mass behavior, promising comfort results have been seen for warm indoor environments where cooling would be needed, simulations have shown 30.9% higher discomfort when in this environments there is not heavy walls. Moreover, for situations where heating is needed, the heating storage capacity of the heavy walls shows some advantages slowing temperature drops during heating reduction and therefore lowering the peak power demanded.