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RE: [EnergyPlus_Support] HVAC Question

Those sound like inputs for the Sizing:Zone object which do not affect how operation is controlled, only the results of autosizing.  So you are probably seeing the effects of running at different part load.  Check the sizes reported to the EIO file. 

You will want to report out system node temperatures to see what you are really getting during operation. 

Some types of HVAC systems allow fine control of supply air deck conditions but these are generally central systems with terminal units.  I am guessing that you have autosized DX coil in a single-zone Unitary package.  E+ controls those to meet the zone load -- so you don't really have control over the supply conditions that will also meet the load.  You may need to hard size everything and then increase the system air flow to actually see an increase in supply temperatures.  



-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx on behalf of lingerfelt30016
Sent: Sat 5/2/2009 9:28 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] HVAC Question
 
Anyone,

I have a model built to simulate a 20,000 sq/ft retail environment "Supermarket".  The model is simulating very close to what we are getting from the utilities in annual energy consumption.  

What I am trying to do is simulate adjustments with the HVAC and determine the energy savings.

Example: I am trying to change the supply air temperature for all my zones by 1 degree C to see the effects on energy.  Then by 2 degree C and so on...

Here is what I am changing but it does not seem correct for the total facility energy.

Zone: Sales
Zone Cooling Design Supply Air: 14 - 19 C
Zone Heating Design Supply Air: 40 - 35 C
Zone Cooling Design Supply Air Humidity Ratio: No change at 0.0085
Zone Heating Design Supply Air Humidity Ratio: No change at 0.008

I am getting a linear result from 1 degree change to 5 degree change.  For every degree a reduction of 0.67%.  I would expect the result to be a little non-linear since the HVAC evaporative coil will not be removing as much humidity and the refrigeration system will now be handling the removal.  

Maybe it is a change in energy moving from one system to the other.

Should I be looking at adjusting other parameters?

Anyway any help would be greatly appreciated!

Scott





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