Zone sensible heating rate drops when having vent. infil. loss.

asked 2016-04-06 12:31:11 -0500

nancynanxiaodan's avatar

updated 2016-04-07 11:28:58 -0500

Dear all,

Firstly, I used the calculated method to modelling the infiltration and natural ventilation in Zone air flow network section, however, I had a very high heat loss due to infiltration and ventilation, and results in the temperature significant drop in some time period.(which I've also include this results). But from the zone air system sensible heating rate, it can be seen that the heating output increased trying to make up the losses.

After I did some research, and then I decided to used scheduled infiltration and natural ventilation set up in Zone air flow section instead. however, I found out that, the zone air system sensible heating rate drops when having the infiltration and ventilation losses, where theoretically should increase to make up this loss to heat the room in designed temperature. However, the temperature is around the desired level of 19 degree.

And I tried to have the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate and Baseboard total heating energy, they are given me very similar results and also drops when having the ventilation and infiltration losses.

My question here is, I didnt change anythiny for Heating system, and when having infiltration and ventilation loss, the system should increase the heating to cover that part of heat loss, however in the results showing that it reduced the heat delivered by Heating system.

I enclosed the results of one zone named dining room as an example, the results are showing in the pic.

Many thanks for your kind help.

The idf file link: IDF file with scheduled ventilation and infiltration

Results of Origin file which used calculated method of vent./infil. image description

Results of the file with the scheduled vent./infil. image description

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Can you describe what HVAC systems you are using to heat and cool the space, or are you doing and ideal loads calculation? Also your first graph shows room temperature but the second doesn't could you maybe plot room temperature on the second as well.

Annie Marston's avatar Annie Marston  ( 2016-04-06 15:28:24 -0500 )edit

Hey @Annie Marston thanks for your reply. I used a gas boiler connect to a water heater(without heating element inside), and this simulation is on 1st Jan, which only have heating requirement.I will update my question, and I will attach the idf file.

nancynanxiaodan's avatar nancynanxiaodan  ( 2016-04-07 05:10:00 -0500 )edit