Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
The performance curves in EnergyPlus define the performance of a specific model. In the case of chillers, the performance curves represent how the chiller responds to loads (the entering water temperature) and the heat rejection fluid (the outdoor air temperature for air-cooling chillers and the entering or leaving condenser water temperature for water-cooled chillers).
The set of performance curves selected is typically based on the manufacturer, size and type of chiller. Depending on controls, the chiller can respond differently to the operating conditions (entering water temp and condenser temp). This is why there are performance curves for so many different chillers.
If you want to use the same performance curves, or the default performance curves, for one or more simulations, you are saying that the chiller performance does not change regardless of operating conditions (i.e., for a given load and operating condition you will get the same capacity and power). This may be OK for parametrics runs where you are testing different insulation thicknesses or some other change to the building model.
Once a set of simulations has been performed you will have an idea of the range of loads (or range of chiller capacity needed to meet those loads) and should select a performance curve set that is representative of the actual chiller that would be used in that case. There is a chiller data set in the ../DataSets folder which has over 100 chiller performance curve sets. You could test the impact a set of chiller performance curves have on the simulation results by creating 2 identical building models. In one model you would use one set of performance curves and in the other a different set of performance curves. The difference in results is solely attributed to the performance curves (or the chiller selected for the project).
