Simulation for between floor concrete slab

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Foo Chin Peng
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Simulation for between floor concrete slab

Post by Foo Chin Peng » Fri Jan 31, 2020 5:00 pm -1100

Lower floor is air conditioned (colder) but upper floor (warmer & wetter) is not, although both are indoors. Condensation happens on the upper floor and is the floor of interest. Is there a difference if I set indoor as upper or lower floor?
Can I set a fix temperature & RH? Daily temperature fluctuations is approximately +/-3C and RH fluctuation is +/-5%.

I have tried swapping the indoor and outdoor and the water moisture level appears to be different. kindly advise.

Christian Bludau
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Re: Simulation for between floor concrete slab

Post by Christian Bludau » Sun Feb 02, 2020 8:54 pm -1100

Dear Foo Ching Peng,

in your case please use indoor conditions for both sides. I think you can express your conditions by using the user-defined sine curve.
Which side is up and down does not matter.

Only if you use outdoor climate at the right side you will get differences, as on the left side radiation, wind and rain is taken in account and on the right side only temperature and relative humidity is used.

Chrisitan

DavidG
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Re: Simulation for between floor concrete slab

Post by DavidG » Wed May 12, 2021 1:00 am -1100

I also need to simulate an internal suspended floor. In my example, above the slab is a cold room. Below the slab is an air conditioned space.
What is the best way to define the cold room conditions on the "left side"?
Does it matter whether the orientation is vertical or horizontal?
Will WUFI understand that there is no radiation and rainfall on the outside?

Christian Bludau
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Re: Simulation for between floor concrete slab

Post by Christian Bludau » Wed May 12, 2021 3:07 am -1100

Dear David,

for the left side you can calcualte indoor climate by switching of the rain and radiation.
For rain set the "adhering fraction of rain" to "no rain" or zero and for radiation set the short wave radiation absorbtivity as well as the long wave radiation emissivity also to zero or leave them empty. Then only the temperature and relative humidity is used.
The inclination/orientation does not matter with the settings above.

Christian

DavidG
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Re: Simulation for between floor concrete slab

Post by DavidG » Sun May 16, 2021 2:22 pm -1100

Hi Christian
Thank you for the advice.
This scenario has 2 indoor conditions - air-conditioning during retail hours then no air-conditioning out of hours.
During out of hours, presumably the temperature and humidity will transition from A/C conditions towards outdoor conditions. My concern is that the increasing humidity will increase condensation risk as the underside of the slab will be cold.
What is the best way to evaluate this scenario i.e. two conditions?
Thanks again
David

Christian Bludau
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Re: Simulation for between floor concrete slab

Post by Christian Bludau » Sun May 16, 2021 8:17 pm -1100

Hi David,
in the indoor climate menu you can find a tab called ASHRAE 160. That allows you to derive the climate from the outdoor conditions according to this standard. It also allows to account for HVAC.
If this is not suitable for you, you can set up your own climate conditions and store them in a wac-file which can be opend in WUFI.
There is an xls-sheet for that, for the standard installation path here:

Code: Select all

c:\Program Files (x86)\WUFI\Tools\CreateClimateFile.xlsm
Christian

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