[Equest-users] Performance Curves for smaller HVAC units

Bobby Almeida bobby at gaiadevelopment.com
Fri Jul 20 13:11:40 PDT 2012

Hi everyone,

I'm making a model and we're looking into the energy impact of higher performance HVAC units. Because of the climate the units work at part load most of the time so the part load efficiencies make a huge difference. For example the 2 units I'm comparing have performances of (12 ton units)

Unit 1                    Unit 2
Full Load              11.0 EER               11.9 EER
75%                        11.2 EER               15.5 EER
50%                        12.1 EER               23.5 EER
25%                        11.4 EER               25.0 EER

I've gone into excel and made curves, normalized them, and found the coefficients to enter into a custom performance curve, as described in previous threads on the user group. I attached that curve to the unit and found that the unit with a high IEER (unit 2) barely performed better than the default curve in eQuest. The project is pursuing LEED certification and we need to get all of the energy savings possible. My main question is how do I best model the performance curves for baseline. I tried changing the curve in baseline so that it would be at 1 no matter the load, which raised the cooling load to a number that seemed too large. Does anyone have experience making good curves for baseline so that I can correctly claim the savings for the high IEER unit? The project also has some large air handlers with high efficiencies at part load. Would it be any different to make a baseline curve for an air handler with VAV?


Bobby Almeida  [cid:image001.jpg at 01CD6679.338F55C0]
Project Engineer

[cid:image002.jpg at 01CD6679.338F55C0]
4051 Glencoe Ave. Suite 5
Marina del Rey, CA 90292
p. 310.591.8172
c. 925.980.2025

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