Question-and-Answer Resource for the Building Energy Modeling Community
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I think I have found the issue, and the solution fixes the zero load in 7.2 as well as 8.2 in the Hospital file. In short, the "WinterDesignDay" category in scheduled loads should specify zero percent load from people, equipment, lights, or anything else that could be taken "credit" for during the design heating calculations. Whatever the changes were in the reheat coil sizing from 7.2 to 8.2 seemed to make the problem more visible.
In the case of (at least) the hospital file, there were low, but non-zero, values for a number of the occupancy and equipment schedules under the WinterDesignDay day. These heat gains offset the envelope heating loss, resulting in no heating. Zeroing these heat gains fixed most of the problem. So, the problem is (un)fortunately as simple as the heating design load calculations being performed incorrectly.
A problem with unmet heating hours in one interior zone remained, and I believe this is addressed in this question, as well as this thread in the Yahoo Group. It seems to be a larger issue with reheat coil sizing for interior zones.
