I do not think the results would be the same, as they are averaged values for different input data..
The peak load conditions for the building may be different for the same day, because the temperature profiles for outdoor dry-bulb and solar radiation pattern are not the same for the designDay and the weather file data.
Compare the input data as well, to see whther they are the same. If you made the designDay profile to track the extreme day weather file ODT, it may give you a better match.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: laxoayi@xxxxxxxxxxxxxxxx
Date: Wed, 21 Sep 2011 19:33:27 +0000
Subject: [EnergyPlus_Support] Re: Peak cooling loads
__._,_.___
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.
![]()
__,_._,___
The peak load conditions for the building may be different for the same day, because the temperature profiles for outdoor dry-bulb and solar radiation pattern are not the same for the designDay and the weather file data.
Compare the input data as well, to see whther they are the same. If you made the designDay profile to track the extreme day weather file ODT, it may give you a better match.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: laxoayi@xxxxxxxxxxxxxxxx
Date: Wed, 21 Sep 2011 19:33:27 +0000
Subject: [EnergyPlus_Support] Re: Peak cooling loads
Thanks Jean, I've reached the same conclusion as yours so I tried to perform one more run with both the sizingperiod:weatherfiledays and the runperiod limited to the same single day. I then changed the "Number of Times Runperiod to be Repeated" to 20 (the results actually converged after 15 repetitions). Despite this, the value of the sizing peak cooling load did not match that of the simulation although peak loads occurred at the same date and time. Anyways I now think I have a better understanding of what is going on thanks to you.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@...> wrote:
>
>
> Okay, sorry. As far as I know the .eio file shows the design loads used for sizing your equipment, i.e. from your sizing run. I'm not sure what sizing parameters sizingperiod:weatherfiledays uses (it may use the worst case day from the weather file and simulate it over and over during sizing...there are also summer weeks data where the week is possibly repeated, however it surely doesn't repeat years untill the start of the year converges with the end of the year which is what you'd have to do to get the sizing max load values the same as the max loads in the year. as the statistical weather year does not include the 1/100 year hot day, unless you tell it to...there is a way I think, most systems are not sized this way.)
>
>
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "omarvelling" <laxoayi@> wrote:
> >
> > Thanks Jean, I appreciate what you mentioned in your reply but I'm not trying to size any system here, I'm only looking for peak cooling loads and that is why I used sizingperiod:weatherfiledays instead of sizingperiod:designday to determine the date/time that the peak load occurs on and its magnitude. Bearing that in mind, should'nt I expect to find the value of the peak load in the .eio file to match the value of the ideal loads air system sensible cooling rate in the output variable file at the same timestep?
> >
> > Thanks a lot, your help is very much appreciated,
> > Omar
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@> wrote:
> > >
> > > The peak cooling load during your statistical weather year is "most probable". The design day is used to size your systems for that once in a hundred years hot day (the same day occuring over and over again untill building temperatures at the beginning and end of the day equal/match those of the day before and after) x sizing:parameter factors. the design day cooling loads are therefore much more than the statistical year's worst day.
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "omarvelling" <laxoayi@> wrote:
> > > >
> > > > Hi all,
> > > >
> > > > I'm trying to determine the peak cooling loads for my model. I used weather file days as my sizing period and also performed an annual simulation using an ideal loads air system to control the zones. I checked the time of the peak design sensible cooling load from the .eio output file and then checked the output variable file but found the value of the ideal loads air sensible cooling rate to be different from that of the .eio file at the same timestep. Is this normal? Am I missing something here? Why do the values of the sizing differ from the annual simulation although I'm using weather file days to perform sizing?
> > > >
> > > > Thanks
> > > >
> > >
> >
>
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@...> wrote:
>
>
> Okay, sorry. As far as I know the .eio file shows the design loads used for sizing your equipment, i.e. from your sizing run. I'm not sure what sizing parameters sizingperiod:weatherfiledays uses (it may use the worst case day from the weather file and simulate it over and over during sizing...there are also summer weeks data where the week is possibly repeated, however it surely doesn't repeat years untill the start of the year converges with the end of the year which is what you'd have to do to get the sizing max load values the same as the max loads in the year. as the statistical weather year does not include the 1/100 year hot day, unless you tell it to...there is a way I think, most systems are not sized this way.)
>
>
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "omarvelling" <laxoayi@> wrote:
> >
> > Thanks Jean, I appreciate what you mentioned in your reply but I'm not trying to size any system here, I'm only looking for peak cooling loads and that is why I used sizingperiod:weatherfiledays instead of sizingperiod:designday to determine the date/time that the peak load occurs on and its magnitude. Bearing that in mind, should'nt I expect to find the value of the peak load in the .eio file to match the value of the ideal loads air system sensible cooling rate in the output variable file at the same timestep?
> >
> > Thanks a lot, your help is very much appreciated,
> > Omar
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@> wrote:
> > >
> > > The peak cooling load during your statistical weather year is "most probable". The design day is used to size your systems for that once in a hundred years hot day (the same day occuring over and over again untill building temperatures at the beginning and end of the day equal/match those of the day before and after) x sizing:parameter factors. the design day cooling loads are therefore much more than the statistical year's worst day.
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "omarvelling" <laxoayi@> wrote:
> > > >
> > > > Hi all,
> > > >
> > > > I'm trying to determine the peak cooling loads for my model. I used weather file days as my sizing period and also performed an annual simulation using an ideal loads air system to control the zones. I checked the time of the peak design sensible cooling load from the .eio output file and then checked the output variable file but found the value of the ideal loads air sensible cooling rate to be different from that of the .eio file at the same timestep. Is this normal? Am I missing something here? Why do the values of the sizing differ from the annual simulation although I'm using weather file days to perform sizing?
> > > >
> > > > Thanks
> > > >
> > >
> >
>
__._,_.___
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.
Your email settings: Individual Email|Traditional
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
Change settings via the Web (Yahoo! ID required)
Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured
Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe
__,_._,___