Relative humidity and comfort

lvidal · Posts: 69 Location: Paris

Hi,

In cooling design tab is a comfort display with a RH% courb. RH is quickly going to 100% and sticks to it
until end of the day (office simulation).

Is that means, cooling calculation does not take into account latent gains ?
Is there a way to specify a max RH for comfort purpose ?

If the calculate cooling power takes sensible and latent loads, why humidity ratio displayed is so high ?

I'm in doubt. Thank you very much for your help.

Laurent

Andy Tindale · Posts: 1111 Location: Stroud

Hi Laurent,

The EnergyPlus calculation does take into account latent gains so perhaps the reason you have such high RH is that there is no ventilation in your zone? If this is not the reason, please send in your file and I will take a look.

Regards
Andy

lvidal · Posts: 69 Location: Paris

Ok, I've investigated a little more further.
Mechanical ventilation is well running.
The problem seems coming from weather data.
The facts :
- site data, humidity is exactly the same as
indoor humidity.
- weather files (FRA_Paris.Orly.IWEC) are corrects
(I checked t°, RH% stats and ddy parameters)

I try to refresh DB database by deleting these files and restarting a simulation. DB downloads new files but the problem persists. I always see RH external air to 100% at max dry temp (see attached file).

Do you have any idea about this problem ?

Other question : is it possible to specify a RH% for a building zone (setpoint, min, max) ?

Tell me if you need some file or more info.
Thanks a lot.
Laurent

Andy Tindale · Posts: 1111 Location: Stroud

I have not received your upload of your model file (which may be a problem at our end) so could you please send it by e-mail.

Andy Tindale · Posts: 1111 Location: Stroud

Laurent,

I apologise for the delay in answering your question. I am away from the office until next week and will not be able to provide an answer until then.

Just one thought though, have you tried using different hourly weather data?

Regards
Andy

lvidal · Posts: 69 Location: Paris

Don't worry I'm not in hurry.

I tried London Gatwick weather data and obtained the same results. I mean, the stat weather file for this location gives HR far less than the 99% shown in site data's cooling design tab.

I don't know if it has any link with our problem but the ddy files (Paris or London) are empty. It contains only location and the following message :
"No Design Conditions found for this location".
I'm surprised, for I have read this ddy file (for Paris) last week and there were design days specifications.

Shoudn't we check basic data files contents and location on my computer ?

Have nice week (I hope holidays !).

See you later,
Laurent

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