Coincident Sizing Factor Mode

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My model has PlantLoop (chillers) and CondenserLoop (cooling towers). I did sizing runs in three different settings.

1. NonCoincident plan sizing
2. Coincident plant sizing, and Coincident Sizing Factor Mode is None
3. Coincident plant sizing, and Coincident Sizing Factor Mode is GlobalCoolingSizingFactor

Sizing:Parameters Cooling Sizing Factor is 1.15.

The autosized chiller capacities are shown in the html files as follows.

"Coincident, None" chiller capacity is approximately 1% smaller than "NonCoincident" chiller capacity. I think Coincident plant sizing worked properly. Of course, I made Do HVAC Sizing Simulation for Sizing Periods Yes and Type of Zone Sum to Use of all AirLoops Coincident.

My question is about Coincident Sizing Factor Mode.

My assumption was that:

• If I choose None, the autosized chiller capacity would be equal to the coincident peak demand.
• If I choose NonCoincident, the autosized chiller capacity would be 1.15 times the coincident peak demand.

However, the simulation results suggest that:

• When I chose None, The autosized chiller capacity = The coincident peak demand x 1.15
• When I chose GlobalCoolingSizingFactor, The autosized chiller capacity = The coincident peak demand x 1.15 x 1.15

Are these the intended function of Coincident Sizing Factor Mode? If that's the case, I should choose None. Who would want to multiply the sizing factor twice?