If you are using DesignDay simulation you may try to change the humidity ratio by changing the wet-bulb value.
You should also monitor the humidity ratio value of the zone, and the values of the adjacent time step.
Total and averged values may be reported in the next time step.
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: yangxiaoshan@xxxxxxxx
Date: Fri, 17 Jun 2011 14:22:23 +0000
Subject: [EnergyPlus_Support] Re: A question about Latent Cooling Load in E+
__._,_.___
Primary EnergyPlus support is found at:
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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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You should also monitor the humidity ratio value of the zone, and the values of the adjacent time step.
Total and averged values may be reported in the next time step.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: yangxiaoshan@xxxxxxxx
Date: Fri, 17 Jun 2011 14:22:23 +0000
Subject: [EnergyPlus_Support] Re: A question about Latent Cooling Load in E+
Hi, Michael
Actually there is no internal load in my case (no people, light and equipment) and the output of internal load by E+ is also zero. So it should not be caused by internal source.
Xiaoshan
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Michael Grant <Michael.Grant@...> wrote:
>
> Hey Guys,
>
> I've been following your discussion since this is similar to what I've been working on lately, but could the imbalance in your cooling load be created by occupancy or office equipment?
>
> Michael Grant, MIT
> Engineering | Systemair Inc.
> (T) 1-506-743-9500
> michael.grant@...<mailto:Michael.grant@...>
> http://www.systemair.net<http://www.systemair.net/>
>
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of yangxiaoshan@...
> Sent: June-17-11 10:29 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: A question about Latent Cooling Load in E+
>
>
>
> Hey, Richard
>
> Thanks a lot. I am not quite understand your idea. Since The Idea Load Air System component does not control zone humidity levels (just control zone air temperature). The zone humidity level varies with the outdoor conditions via infiltration. For "Idea Load Air System",the constant air temperature and humidity of the air supplied for cooling the zone are 13 degree Celsius and 9 g/kg. According the ASHRAE sizing method (used by E+), total Cooling is the rate at which total energy (sensible and latent) is removed from the mixed outside and return air stream in order to bring the mixed air stream to the specified temperature and humidity ratio of the supply air stream. For this case, the only source of latent heat gain is by infiltration, and the infiltration latent heat gain should be equal to total latent cooling load. But it isn't......
>
> Xiaoshan
>
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad <RRaustad@> wrote:
> >
> > Are you reporting the zone relative humidity? If the zone moisture level
> > is dropping, this would explain the difference. You need to keep the
> > zone conditions constant for this to work.
> >
> > On 6/17/2011 8:56 AM, yangxiaoshan@ wrote:
> > >
> > > Hi,
> > > Thanks for your reply. I had set the infiltration rate to 0 or other
> > > values. If ACH is 0, there is no latent cooling load and total cooling
> > > load equals to total sensible cooling load. That makes sense. But once
> > > the ACH is not 0, the infiltration heat gain is always less than
> > > latent cooling load. I do not know what else items could be also
> > > included in the latent cooling load component.
> > >
> > > Best,
> > > Xiaoshan
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, YuanLu Li <yli006@>
> > > wrote:
> > > >
> > > >
> > > > Try changing the infiltration air change per hour to zero and to 2
> > > to compare.
> > > >
> > > > There may be other compoent included in the total cooling load.
> > > >
> > > > Dr. Li
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > From: yangxiaoshan@
> > > > Date: Fri, 17 Jun 2011 06:37:59 +0800
> > > > Subject: [EnergyPlus_Support] A question about Latent Cooling Load in E+
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Dear Colleagues,
> > > >
> > > >
> > > > I got a question about latent cooling load in EnergyPlus. The
> > > simulation settings are: a single zone with constant cooling setpoint
> > > (26â"f through the day), no internal heat gain, 1 air changes per hour
> > > and "Idea Load Air System" automatically used for HVAC configuration.
> > > Theoratically, due to there is no internal heat gain in this case, the
> > > follow correlation should be valid: "Total cooling load - Total
> > > sensible cooling load = Latent cooling load = Infiltration latent heat
> > > gain". But the simulation results shown that the infiltration latent
> > > heat gain is always less than the latent cooling load (Total cooling
> > > load - Total sensible cooling load), 2% for this case (8-9% less was
> > > found in other simulation case). I cannot understand why the
> > > infiltration heat gain is not equal to the calculated latent cooling
> > > load. Really headache! Look forward to discussing with you, thanks
> > > very much.
> > > >
> > > > Best regards,
> > > > Xiaoshan
> > > >
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
Actually there is no internal load in my case (no people, light and equipment) and the output of internal load by E+ is also zero. So it should not be caused by internal source.
Xiaoshan
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Michael Grant <Michael.Grant@...> wrote:
>
> Hey Guys,
>
> I've been following your discussion since this is similar to what I've been working on lately, but could the imbalance in your cooling load be created by occupancy or office equipment?
>
> Michael Grant, MIT
> Engineering | Systemair Inc.
> (T) 1-506-743-9500
> michael.grant@...<mailto:Michael.grant@...>
> http://www.systemair.net<http://www.systemair.net/>
>
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of yangxiaoshan@...
> Sent: June-17-11 10:29 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: A question about Latent Cooling Load in E+
>
>
>
> Hey, Richard
>
> Thanks a lot. I am not quite understand your idea. Since The Idea Load Air System component does not control zone humidity levels (just control zone air temperature). The zone humidity level varies with the outdoor conditions via infiltration. For "Idea Load Air System",the constant air temperature and humidity of the air supplied for cooling the zone are 13 degree Celsius and 9 g/kg. According the ASHRAE sizing method (used by E+), total Cooling is the rate at which total energy (sensible and latent) is removed from the mixed outside and return air stream in order to bring the mixed air stream to the specified temperature and humidity ratio of the supply air stream. For this case, the only source of latent heat gain is by infiltration, and the infiltration latent heat gain should be equal to total latent cooling load. But it isn't......
>
> Xiaoshan
>
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad <RRaustad@> wrote:
> >
> > Are you reporting the zone relative humidity? If the zone moisture level
> > is dropping, this would explain the difference. You need to keep the
> > zone conditions constant for this to work.
> >
> > On 6/17/2011 8:56 AM, yangxiaoshan@ wrote:
> > >
> > > Hi,
> > > Thanks for your reply. I had set the infiltration rate to 0 or other
> > > values. If ACH is 0, there is no latent cooling load and total cooling
> > > load equals to total sensible cooling load. That makes sense. But once
> > > the ACH is not 0, the infiltration heat gain is always less than
> > > latent cooling load. I do not know what else items could be also
> > > included in the latent cooling load component.
> > >
> > > Best,
> > > Xiaoshan
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, YuanLu Li <yli006@>
> > > wrote:
> > > >
> > > >
> > > > Try changing the infiltration air change per hour to zero and to 2
> > > to compare.
> > > >
> > > > There may be other compoent included in the total cooling load.
> > > >
> > > > Dr. Li
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > > From: yangxiaoshan@
> > > > Date: Fri, 17 Jun 2011 06:37:59 +0800
> > > > Subject: [EnergyPlus_Support] A question about Latent Cooling Load in E+
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Dear Colleagues,
> > > >
> > > >
> > > > I got a question about latent cooling load in EnergyPlus. The
> > > simulation settings are: a single zone with constant cooling setpoint
> > > (26â"f through the day), no internal heat gain, 1 air changes per hour
> > > and "Idea Load Air System" automatically used for HVAC configuration.
> > > Theoratically, due to there is no internal heat gain in this case, the
> > > follow correlation should be valid: "Total cooling load - Total
> > > sensible cooling load = Latent cooling load = Infiltration latent heat
> > > gain". But the simulation results shown that the infiltration latent
> > > heat gain is always less than the latent cooling load (Total cooling
> > > load - Total sensible cooling load), 2% for this case (8-9% less was
> > > found in other simulation case). I cannot understand why the
> > > infiltration heat gain is not equal to the calculated latent cooling
> > > load. Really headache! Look forward to discussing with you, thanks
> > > very much.
> > > >
> > > > Best regards,
> > > > Xiaoshan
> > > >
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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