I am using Design Builder ver 5.0 to model a small retail store with an entry vestibule that has a small electric cabinet heater, but no cooling unit. The vestibule floor area is 5-ft by 4-ft and has an exterior glass door, an interior glass door, large windows on two sides, and is exposed to ambient on three sides. In the summer it's basically a walk-through oven. Not a good design solution, but one that we've all experienced. For purposes of ASHRAE 90.1, I think it is classified as a conditioned heated space. The simulation location is in Climate Zone 6B. The zone heating setpoint is 50 F and cooling setpoint is 99 F. The maximum simulated dry bulb temperature is 105 F, but zone cooling set point not met time exceeds the number of hours when the temperature is above 99 F. From the attached chart, it appears that the simulation controls think the cooling set point is around 74 F, which is the cooling setpoint for other zones in the store. I have turned off mechanical cooling and the Design Builder inputs require a number between -58 F and 176 F. I need to reduce or eliminate the unmet hours. So, my question is, how does EnergyPlus (or Design Builder) determine the setpoint for calculating unmet hours for a zone? What have I overlooked? EntryVestibuleCoolingSetPointNotMet.png
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