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[EnergyPlus_Support] Re: Passive gains breakdown - which variables?



Thanks so far! I'm still investigating this issue any further help is appreciated, I'll try to explain what I am trying to achieve. 

Basically I am trying to perform an annual energy balance on a building (no heating required). So if I sum all of the gains in all of the zones, this should equal the amount of cooling required. So I need to break down all the heat gains across the building envelope (solar, conduction, infiltration) and the internal heat generation (people, electric, lights). I ran a simulation and have the following results: 

	Annual Sum or Average	Grand total
MTR ZONE INFILTRATION TOTAL HEAT GAIN [MWh]	4.4	
MTR ONE INFILTRATION TOTAL HEAT LOSS [MWh]	0.0	
MTR ZONE WINDOW HEAT GAIN ENERGY [MWh]	7.1	
MTR ZONE WINDOW HEAT LOSS ENERGY [MWh]	0.6	
MTR ZONE PEOPLE TOTAL HEAT GAIN [MWh]	2.4	
MTR ZONE LIGHTS TOTAL HEAT GAIN [MWh]	2.9	
MTR ZONE ELECTRIC EQUIPMENT TOTAL HEAT GAIN [MWh]	2.0
Grand total gains: 	18.9		
MTR ZONE/SYS SENSIBLE COOLING ENERGY [MWh]	18.4

18.9 is close to 18.4 - but then where are the conductive gains from the outside air to the inside air???

I tried again but this time disabled infiltration:

	Annual Sum or Average	Grand total
MTR ZONE INFILTRATION TOTAL HEAT GAIN [MWh]	0.0	
MTR ONE INFILTRATION TOTAL HEAT LOSS [MWh]	0.0	
MTR ZONE WINDOW HEAT GAIN ENERGY [MWh]	7.1	
MTR ZONE WINDOW HEAT LOSS ENERGY [MWh]	0.6	
MTR ZONE PEOPLE TOTAL HEAT GAIN [MWh]	2.4	
MTR ZONE LIGHTS TOTAL HEAT GAIN [MWh]	2.9	
MTR ZONE ELECTRIC EQUIPMENT TOTAL HEAT GAIN [MWh]	2.0	
Grand total gains: 	14.5		
MTR ZONE/SYS SENSIBLE COOLING ENERGY [kWh]	17.3

Here I expected the sensible total cooling to be reduced by 4.4 since the infiltration is now 0. 

What is wrong with this approach? How do I meter the conductive heat gain - the sum of all heat transferred across all external surfaces? 

Other simulation programs like TRNSYS and Ecotect have explicit output for ie/ conduction and it all sums up in the balance, but I can't figure it out with EnergyPlus!

Thanks again, I need this type of results for a certification standard. 

Cheers,

Marcus




--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jia Hu <hujia06@...> wrote:
>
> Hi:
> 
> For Direct solar gain through windows, consider
>  (a) Window Transmitted Beam-to-Beam Solar;
>  (b) Window Transmitted Beam Solar.
> 
> Window Transmitted Beam Solar = Window Transmitted Beam-to-Beam Solar  +
> Window Transmitted Beam-to-Diffuse Solar
> 
> 
> 
> 2011/7/15 <miguel@...>
> 
> > **
> >
> >
> > Marcus
> >
> > General:
> > Window Heat Gain Energy
> > Window Heat Loss Energy
> >
> > Diffuse you can start with Window Transmitted Diffuse Solar but it depends.
> >
> > There are so many variables precisely to allow you to perform different
> > analysis. It depends really on what you want to know. I understand how
> > intimidating all these variables can be, but in the long term it is very
> > rewarding to study the manuals.
> >
> > Generally speaking if you are fine tuning the envelope I would use the
> > variables starting with Window rather than Zone so you can check window by
> > window.
> >
> > But depending how you divide the zones of your building, its size and
> > orientation,  Zone variables might work fine. Or make no difference: example
> > one window per zone.
> >
> > Transmitance you set in  materiala
> > Shadding the walls you can use shading building detailed.
> >
> >
> > Miguel Pacheco
> >
> > Doutorando / Graduate Student
> > Laboratório de Eficiência Energética em Edificações - LabEEE
> > Universidade Federal de Santa Catarina - UFSC
> > http://www.labeee.ufsc.br
> >
> > Contato/Contact:
> >
> > Florianópolis: 55 48 3721 5184 / 55 48 3721 5185
> > São Paulo: 55 11 3091 2510
> > Celular: 55 48 88 43 91 65
> >
> >
> >
> >
> > Citando Marcus <clasz14@...>:
> >
> > > Thanks for the comments, I will check indirect solar as well. However
> > > if anyone has the actual variable object names to use that would be a
> > > great help, there are so many variables that I'm not sure which ones
> > > to use!
> > >
> > > Cheers,
> > >
> > > Marcus
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, miguel@ wrote:
> > >>
> > >> Hello Marcus
> > >>
> > >> I would suggest you check also indirect solar gains through windows.
> > >> From my experience they are significant in cooling dominated
> > >> climates. Even in heating dominated climates, during their hot
> > >> season depending on the insulation of the building they can be
> > >> significant.
> > >>
> > >> I would also check the effects of radiant heat on roof and wall, by
> > >> choosing lower absorptivities AND shading walls.
> > >>
> > >> You can use zone window solar gain  for solar gains through windows
> > >> but I would suggest you check window heat balance  for a fine tune
> > >> of the envelope.
> > >>
> > >> district cooling does not gauge heat gains.
> > >>
> > >> Migue
> > >>
> > >> Citando Marcus <clasz14@>:
> > >>
> > >> > I need to analyze the passive performance of a building in a cooling
> > >> > dominated climate. I need to meter the following passive heat gains:
> > >> >
> > >> > - Conduction through the envelope
> > >> > - Direct solar gain through windows
> > >> > - Infiltration gain
> > >> > - Total heat gain (to check the sum of these three)
> > >> >
> > >> > So far I've used the following approach, metering these variables:
> > >> >
> > >> > - Conduction through the envelope
> > >> >    . ???
> > >> > - Direct solar gain through windows
> > >> >    . Zone Transmitted Solar Energy (??)
> > >> > - Infiltration gain
> > >> >    . Zone infiltration total heat gain
> > >> > - Total heat gain
> > >> >    . Cooling:DistrictCooling ??
> > >> >
> > >> > This isn't producing quite what I expect - can someone direct me to
> > >> > more appropriate variables? Especially the conduction gain? Am I
> > >> > missing something?
> > >> >
> > >> > Cheers,
> > >> >
> > >> > Marcus
> > >> >
> > >> >
> > >>
> > >> Miguel Pacheco
> > >>
> > >> Doutorando / Graduate Student
> > >> Laboratório de Eficiência Energética em Edificações - LabEEE
> > >> Universidade Federal de Santa Catarina - UFSC
> > >> http://www.labeee.ufsc.br
> > >>
> > >> Contato/Contact:
> > >>
> > >> Florianópolis: 55 48 3721 5184 / 55 48 3721 5185
> > >> São Paulo: 55 11 3091 2510
> > >> Celular: 55 48 88 43 91 65
> > >>
> > >> ----------------------------------------------------------------
> > >> This message was sent using IMP, the Internet Messaging Program.
> > >>
> > >
> > >
> > >
> >
> >
> >
> >
> > ----------------------------------------------------------------
> >
> > This message was sent using IMP, the Internet Messaging Program.
> >
> >  
> >
>




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