Re: [EnergyPlus_Support] load and energy balance

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

1.  The easiest way to determine the sensible load requirements to 
maintain the specified thermostat setpoints is to use the purchased 
air simulation with no capacity limits and include outside air if 
applicable.  This will also provide a rough approximation of latent 
load requirements.  

2a.  If the thermostat setpoints are being met, then the cooling plant
is providing enough cooling.  This is the only measure of performance
which is available.  You can use the new report:table:bin feature to
see the distribution of temperatures in the zones to assess if
setpoints are being met.

2b.  It is very difficult to do a simplified energy balance 
calculation which will agree with the simulation result.  To balance 
the building envelope, you must reduce the problem to a steady-state 
condition by defining a constant temperature day with no sunshine.  
Balancing loads within the HVAC simulation is easier since each time 
step is a quasi-steady-state simulation, but there are still many 
details which must be accounted for.

Mike




On 21 Sep 2003, at 16:36, Helen Xing wrote:

> Hello, there.  I was just wondering what is the best/easiest way to
> 
> 1) get a building's hourly total cooling loads from E+
> 2) verify that the cooling plant is providing enough (or not enough)
> energy to meet the building load on an hourly basis
> 
> I pulled out some outputs from E+ and tried to do a balance check. 
> But it didn't seem to match.  While checking the model, I wonder if I
> used the right outputs from E+.  Thanks a lot in advance for your
> help.
> 
> Regards,
> Helen Xing
> 
> 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx


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