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Re: [TRNSYS-users] Relative humidity of Kitchen is illogical (with attached files)



Ismail,

  Type56 assumes that zones have neutral pressure. If you add air to a zone, it is assumed that the same mass of air leaves the zone by some means. The same would be true if you were to actively extract air from the zone; more air would come in to replace the air that you extracted. The issue, I think, is where the air that comes into the zone comes from. If it comes from a humid source then the zone humidity is going to go up. If the air comes from a dry source then the zone humidity will go down. One of the challenges with natural ventilation is that if the building is cooler than the ambient when natural ventilation is activated then humid air comes into a cool space from outside and the RH in the space goes way up (cool air can hold less moisture than warm air).

kind regards,

 David



On 07/10/2017 08:43, Issmail OUHALLOU via TRNSYS-users wrote:
Dear colleagues,

I am trying to simulate the impact of natural ventilation by calculating the mean air velocity entering through the window (in m/s) according to the equation below:

​I got the results as shown in attached files before and after natural ventilation. The humidity has increased enormously !

I figure out that in TRNBuild the air cannot be extracted from the zone ! How can I extract the air from a zone after activating natural or mechanical ventilation ?

Does anyone have experience to deal with such a problem ?

Thanks in advance,
Best
Ismail


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Ismail OUHALLOU
Green building & Sustainability consultant

Morocco
P:+212 620 548 116
F:+212 522 326 440





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David BRADLEY
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