I want to optimize chilled water loop sizing and configuration to meet the cooling load of a building. I have a detailed model that includes thermal zones and AHUs but I don't want to change them during the optimization process. My concern is choosing a variable as the constraint for thermal comfort. I need this to evaluated whether my plant loop can meet the demand or not. I tried Unmet hours but I got weird results and I cannot work with that. Is there any variable in energyplus that I can ensure it can evaluate my plant sizing results?