I used OpenStudio to create the energy model and used ResultsViewer to check the output. There are a lot of thermal zones only try to meet the heating thermostat schedule (70F=21.1C) during the whole year. The screen shot of one zone is presented as following to show the details (blue line shows the zone temperature, while the black is deck temperature). However, I have both the cooling and heating thermostat schedules for these zones. As a comparison, I also added another zone's output to show how it meet both cooling (75F=23.8C) and heating (70F=21.1C) thermostat schedules.

Does anyone get the same situation before? Based on this output, my second question is how OpenStudio decides when is on cooling mode and when is on heating mode? Based on my understanding, the different mode is corresponding to the different zone thermostat schedule.

Zone that only meet the heating thermostat schedule and the AHU that services this zone:

Zone that meet both cooling and heating thermostat schedules and the AHU that services this zone: