Re: [EnergyPlus_Support] How can I get the latent load of a living room?

["Michael J. Witte" <mjwitte@xxxxxxxx>]

Please see reponses below.  Mike


On 9 Aug 2004, at 14:16, lizhenghdf wrote:

> Dear Mike:
> 
> Thank you for your post! I have uploaded a file named "W sys 
> SHR.idf". I want to get the latent load of a living room that an AC 
> should remove, not the latent load that the equipment can remove 
> related to its SHR. Because the "Zone/Sys Moisture Load Rate 
> Predicted" is incorrect, I add "AIR CONDITIONER:WINDOW:CYCLING" in 
> order to simulate a full HVAC system, but I also cannot get the 
> result. What can I do?

0.  The best you can do is to turn on RH control on the window air conditioner, 
see the WindACRHControl.idf example file.  This will still overpredict the 
latent load at times when the base latent removal dries the space below the RH 
setpoint.  

> 
> Besides, I have other questions:
> 
> 1.In the case report, why the "LIVING ROOM:People-Sensible Heat 
> Gain" is similar to the "LIVING ROOM:People-Total Heat Gain", where 
> is the latent heat gain? I think the latent load part should be 30-
> 40% of the total load of people.
> 

1.  The activity level schedule is set at 66 W/person.  This is very low and 
will result in a low latent fraction.  Note that the activity level table in 
the Input Output Reference is in W/m2 and the values must be multiplied by 
approximately 1.8 to represent the average adult.  Also, the amount of latent 
load from people is affected by the temperature and humidity in the zone.  See 
the Input Output Reference (p. 193) and the Engineering Reference (p. 324) for 
more details.

> 2.What is the meaning of "COIL-LIVING:DX Coil Sensible Cooling 
> Rate"and "COIL-LIVING:DX Coil Latent Cooling Rate"? Why there is 
> much difference between them and "RAC-LIVING:Window AC Sensible Zone 
> Cooling Rate","RAC-LIVING:Window AC Latent Zone Cooling Rate", 
> especially the latent one?
> 

2.  The "DX Coil" cooling variables represent the gross cooling load on the 
coil, including loads from outside air and fan heat.

The "Window AC" cooling variables represent the net cooling delivered to the 
zone.  If the outside air is hot and humid, the "DX Coil" values will be 
larger.  If the outside air is cool and dry, the "DX Coil" values will be 
smaller than the "Window AC" values.

> 
> Thanks!
> 
> Best Regards
> LI
> 
> 
> 
> 
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
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> in the Files area of the Support Web Site.
> 
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> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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