----- Original Message -----From: James V Dirkes II, PESent: Tuesday, February 15, 2011 5:48 PMSubject: RE: [EnergyPlus_Support] output meter definition and/ or difference.
Dear Bill,
The variables available for a given E+ run depend on the construction and HVAC systems of the model. Chiller variables, for example, will not be available for an all-DX cooling system. Available report variables are shown in the .RDD file (after you get the thing to run!) and available meter variables are shown in the .MDD file.
Without looking closely, I think that you have chosen an energy variable (?District Cooling??) and a load variable (??Energy Transfer??). These will probably differ somewhat and you may be able to figure out why they differ by looking at the .MDD file to see what is included in each.
I?m on the US Eastern time zone, so I?m not able to give this much more attention before bedtime! I hope that steers you in the right direction.
The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Bill Henry
Sent: Tuesday, February 15, 2011 8:13 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] output meter definition and/ or difference.
I have been using EnergyPlus to model the external energy input for large buildings. I try to keep the model rather simple, and construct it OpenStudio.
When I try to define my report meters the choices are confusing and I don't always get the same choices project to project.
This time I constructed a 110,000 square foot two story building with about 30% glazing. Just one zone with the second floor not included in the model.
In any case. I set up an output variable as "Outdoor Dry Bulb " . Here are a two of the relevant output meters offered by EP that I ran just to compare results. 1) District Cooling:Facility, 2) Cooling Energy Transfer:Zone:Building
Question #1: For the two meters I chose the results varied by 25! % or more when the cooling demand was applied for just say 4 hours out of 24 or more during the winter. Summer demand was vary consistent between the two meters. What I found was that Cooling Energy Transfer:Zone:Building was greater than Cooling Energy Transfer:Zone:Building when the two meters did not agree.
Question #2: How do I evaluate the choices between meters. Are there other meters that are not shown when I make a selection? Other choices that were offered for this project:1) Cooling Energy Transfer 2) District Cooling:HVAC 3) Cooling"DistrictCooling, can you explain the differences?
Bill Henry
William R Henry, P.E
Consulting Engineer
San Jose, CA
Office: (408) 629-9953
Cell: (408) 439-8818
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