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Some Zones Only Meet the Heating Thermostat Schedule

asked 2016-04-20 21:02:21 -0500

lyw0211 gravatar image

updated 2016-04-21 14:58:57 -0500

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:

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

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Could you please more detail e.g. type of HVAC system

Waseem gravatar image Waseem  ( 2016-04-21 05:55:58 -0500 )edit

@Waseem, Thanks for your reminder! The details of AHUs are added.

lyw0211 gravatar image lyw0211  ( 2016-04-21 15:00:02 -0500 )edit

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answered 2016-04-22 21:06:05 -0500

From your graphs, the cooling and heating set point temps are held quite well. It's not uncommon that the cooling/heating set point may not be met on an extreme day. You should zoom in on the questionable day to see what's happening. Cooling and heating loads are calculated by the program and the load in each zone is determined before the HVAC system operates. If a zone does not meet the set point, air flow/capacity to that zone is questionable.

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Thanks, @rraustad! That's helpful!

lyw0211 gravatar image lyw0211  ( 2016-04-25 18:04:20 -0500 )edit

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Asked: 2016-04-20 21:02:21 -0500

Seen: 148 times

Last updated: Apr 22 '16