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is this normal in designbuilder ?

asked 2020-09-22 08:18:13 -0600

oussama-ka's avatar

so in a zone when i'm using a simple HVAC in design building i stimulate my projet and i get some confusing results as you can see in the photo why the outside dry air temperature in summer is less than the air temperature does that means that in summer the heating is working instead of cooling or as i can see the HVAC is not working : C:\fakepath\w.PNG

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answered 2020-09-22 10:06:40 -0600

To know if heating is working, you would look at the HVAC energy chart in DesignBuilder. You can generate this in the same way that you generated this air temperature chart if you select "1-All" for your plotting Data setting after you finish a simulation (see below). In my example, there is only a little bit of heating applied once in the morning of a few days.

image description

If heating is not working, and the zone air temperature is higher than the outdoor air temperature, this can be caused by lighting, equipment, and occupants in the space. If the temperature plots you attached are from a weekday, then HVAC should definitely be available to operate, but it looks like there is no cooling thermostat -- or at least the cooling thermostat is above 34C, which is unlikely. If the temperature plots you attached are from a weekend, then it looks like the internal gains (lighting, equipment, and occupants) are generating enough heat to overcome conduction losses to outdoor air.

It's hard to say without knowing more details or inputs for your DesignBuilder model. Check your cooling & heating thermostat setpoint temperatures first, then look at internal gains inputs.

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I agree with Aaron. The zone temperature does not seem to be controlled. I would also suggest to check the HVAC operation schedules at HVAC tab.

You should have a better understanding of your model results by running a Summer design week with hourly results. The annual period overview will not give you enough details for model debugging.

Luís Filipe S.'s avatar Luís Filipe S.  ( 2020-09-22 10:57:36 -0600 )edit

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Asked: 2020-09-22 08:18:13 -0600

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Last updated: Sep 22 '20