RE: [EnergyPlus_Support] HVAC Question

Dear Scott,

Although I've never attempted modeling a supermarket, I'm aware that an important relationship within them is the energy exchange between the HVAC and the refrigerated casework. More humidity in the space causes more frost in the casework. Low humidity in the space helps the casework and costs more HVAC energy.

For this reason I recommend looking closely at the interaction between sensible and latent energy. First, your model should attempt to simulate this sensible / latent / frost interaction. Second, look to see how they interact to understand the reason energy savings are acting as they are.

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 lingerfelt30016
Sent: Saturday, May 02, 2009 11:28 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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