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Why my unconditioned zone is having mean RH greater than 90% ?

asked 2019-01-22 07:23:47 -0500

Smruti's avatar

updated 2019-03-05 06:58:27 -0500

dhollman's avatar


I have made a model to simulate a hospital having both conditioned and unconditioned zones. I have provided a water cooled chiller for AHUs and a cooling tower. The conditioned zones are meeting comfort criteria. The unconditioned zone although temperature is similar to ambient, but the mean humidity for all unconditioned zones are always greater than 90%. I don't think it is practical, because making the loads minimum also is having more than 90% humidity.

Can somebody help?

Regards, Smruti

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answered 2019-01-22 07:52:22 -0500

This usually means there is no infiltration to the unconditioned zones. Some form of mass transfer between the unconditioned zones and other conditioned zones (mixing, cross-mixing, ventilation, etc) or outdoors (infiltration or ventilation) should solve the problem.

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answered 2019-01-22 23:57:31 -0500

Smruti's avatar

@rraustad, thank you very much for the reply.

Yes now the unconditioned zones are working fine.

But, I want to mention one observation here.

image description

This outdoor air specification for ventilation doesn't work for unconditioned zones.

When, I changed to infiltration to 5 ACH, it worked, as in image below:


Could someone explain this?

Regards, Smruti

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Asked: 2019-01-22 07:23:47 -0500

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Last updated: Jan 22 '19