constant ventilation rate

Irene.Pau · Posts: 20

Hello,

Is there a way to set a constant ventilation rate of, say, 2 ac/h, throughout the entire year simulated? I thought that by setting the maximum in-out delta T to -50�C, I would be able to do this, but it is reducing the ventilation rate during the coldest times of the year (probably due to the heating setpoint T? I've already set this to the minimum value of 0�C).

Regards,
Irene

bhandari · Posts: 120

Irene,
You can set constant ach of 2 either by mechanical ventilation and/or natural ventilation (scheduled) in HVAC tab. You need to assign schedule as always on (value 1) if you want to use 2 ach throughout the year or can control it by defining different schedule values. Please see the figure below (I put value of 2.0 in both mechanical and natural ventilation just as an example. these two values will be added). Please note that you also have an option of including/not inlcuding infiltration under construction tab.

regards,
Mahabir

Irene.Pau · Posts: 20

Mahabir,

I have done exactly what you have, but the ventilation rate drops off at the coldest times of the year, so I was wondering if it's simply because the heating setpoint (min value of 0�C) kicks in and overrides the constant ventilation rate.

I've attached my *.dsb file here. Please let me know if you need the weather file as well.

Cheers,
Irene

bhandari · Posts: 120

Irene,
My omission. I forgot to mention that in case you decide to define outside air (constant ach)using Natural ventilation, the flow is switched off if the zone air temperature falls below the Ventilation setpoint temperature set under Environmental Control on the Activity tab. I hope this explains the dropped ach in your model..
regards,
Mahabir

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