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RE: [EnergyPlus_Support] Re: Simplest way to control RH in a zone

Hi, Toby
I do not know why you wanted to do this exercise.
If you can cool and control the single room to 25°C you should already have a cooling system of some sort.  Calculate what is the dew point temperature for 55% RH at 25°C.  A humidistat in a xone will do this calculation.  Cool the circulating air to that temperature, all the excess moisture would be condensed out at the cooling coil.
If the zone do not have sufficient heat to warm the air up to 25°C, add a reheat heater. 
All these are in the EPlus HVACsystem.

For a single room a window unit would do the trick.  If you want to control the temperature and humidity exactly, you may need a system desinged for a clean room or an operating theatre of a hospital.


It is ridiculous trying to do this for 1-8 person for a whole year.  Pardon me for saying so.
You do not know how much a person would sweat.  The person does not sweat the whole day.  For the whole year, there are Winter and Summer.  
When a person is working out in a gym, the maximum activity level is about 400 watt.  Not all the sweat is evaporated and condensed again by the HVAC.  
If this person works out 4 hours a day all the year around, Winter months does not count, as he will be helping to heat the zone.  For Sumer time, 183 x 4 x 0.200 kwh would be the total energy added to the system.   If the person is not working out  in a gym, the amount would reduce to 1/4.
Do you know that the moisture from the outdoor air may be a lot more than that from the person.  So your question on ventilation load also does not make sense.
 Dr. Li  

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: tobycheung00@xxxxxxxxxxx
Date: Thu, 13 Sep 2012 12:22:43 +0000
Subject: [EnergyPlus_Support] Re: Simplest way to control RH in a zone

Thanks for your reply.

Yes, I have found this object.
Yet, it seems work with a serious of components (such as heating coil, humidifier, in/out nodem ... etc.) which I am not very familiar with.

And I have tried the example files which related to RH control.
It seems include alot .... and not easy to understand by myself.

Well, if I just want a zone with temp=25oC and RH=55% for all hours within a year. Which kinds of components do I need to concern with ? Just very simple setup and any types of AC system is ok for me ~~ Many thanks.

Toby Cheung

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Vaibhav Jain <vaibhav.energyarchitect@...> wrote:
> Have you checked, ZoneControl:Humidistat object? You will understand its
> functioning from IO reference.
> Vaibhav Jain
> www.vaibhavjain.co
> On 13 September 2012 13:30, tobycheung00 <tobycheung00@...> wrote:
> > **
> >
> >
> > Dear All,
> >
> > Can anyone please suggest me the simplest (use minimum connected
> > equipment) way to control the relative humidity in a zone ?
> >
> > My condition is easy. I want to control the temperature and the relative
> > humidity in a zone, and finally want to find out the hourly ventilation
> > load of increasing number of occupant(1~8) within a year, according to
> > hourly outdoor conditions change.
> >
> > Its easy to control the zone temperature and yield the ideal zone load.
> > Yet adding humidity control seems a lot more complicated...
> >
> > Could you please suggest which components must be added in order to
> > facilitate the Humidity control. Many thanks.
> >
> > Toby Cheung
> >
> >
> >


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