EnergyPlus pre-cool results offset from baseline

asked 2024-09-26 13:20:09 -0500

113 ●2 ●5

Hello,

Following up on my previous post, I am using the DoE High-Rise Apartment Prototype building model to evaluate a pre-cooling strategy and assess the potential for load shifting. In the model, I’ve limited the coil cooling capacity and the supply fan airflow rate based on calibration results and the real-life building's chiller system capacity.

The model was calibrated with a constant cooling setpoint of 75°F, as well as user-specified coil cooling capacity and supply fan airflow rate.

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However, after switching to a pre-cooling schedule, I noticed an overnight offset pattern in both the whole-building load and HVAC load. Below are the pre-cooling schedule and a comparison of the two simulation results.

SCHEDULE:COMPACT,
    PRECLG_CLGSETP_APT_SCH,    !- Name
    Temperature,              !- Schedule Type Limits Name
    THROUGH: 12/31,           !- Field 1
    For: SummerDesignDay,     !- Field 2
    Until: 24:00,             !- Field 3
    23.89,                    !- Field 4
    For: Weekday,             !- Field 5
    Until: 13:00,             !- Field 6
    23.89,                    !- Field 7
    Until: 15:00,             !- Field 8
    23.33,                    !- Field 9
    Until: 19:00,             !- Field 10
    25,                       !- Field 11
    Until: 24:00,             !- Field 12
    23.89,                    !- Field 13
    For: Weekend AllOtherDays,    !- Field 14
    UNTIL: 24:00,             !- Field 15
    23.89;                    !- Field 16

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Then, I checked the zone level data, similar trend can be observed. In the early morning, two temperature profiles aligned closely. But the cooling load and fan power showed different patterns. I was wondering what could cause this issue?

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