Preheating Strategy of Intermittent Heating for Public Buildings in Cold Areas of China

Intermittent heating is commonly applied and considered as energy efficient in public buildings in cold areas considering their occupation schedules. Rational preheating time is of significance to guarantee indoor thermal comfort, facility safety and energy conservation in intermittent operation strategy. In this paper, indoor temperature and energy consumption under continuous and intermittent heating conditions of a typical office building in Shijiazhuang City, China, are, respectively, studied using DeST-C software. The influence of building thermal parameters and outdoor temperature on preheating time is also studied. The results show that indoor temperature fluctuates periodically within a larger margin in a day under intermittent heating while it is relatively stable under continuous heating. The lowest indoor temperature of energy-efficient buildings and ordinary ones is as low as 11 and 9 °C, respectively, under intermittent heating during the coldest days in winter. The preheating time for energy-efficient buildings is 2, 2 and 1 h; for non-energy-efficient buildings, it is 3, 3 and 1 h during the early, peak and final heating period. The energy-saving rate of intermittent heating compared with the continuous heating mode is above 20% for both energy-efficient buildings and ordinary ones in cold area.