Revision history [back]

The other approach could be to use EMS (also supported by DesignBuilder) in order to override weather parameters instead of changing a weather file. Choose environment-related actuators for outdoor dry bulb temperature and solar radiation (direct and diffuse) and change their values at the beginning of each timestep. The attached example changes direct and diffuse solar radiation to 0 and sets the outdoor dry bulb temperature to 18C.

! Weather file outdoor air dry bulb temperature
EnergyManagementSystem:Actuator,
    oDBT,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Outdoor Dry Bulb;              !- Actuated Component Control Type

! Weather file diffuse solar radiation
EnergyManagementSystem:Actuator,
    oDifSolar,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Diffuse Solar;              !- Actuated Component Control Type

! Weather file direct solar radiation
EnergyManagementSystem:Actuator,
    oDirSolar,               !- Name
    Environment,             !- Actuated Component Unique Name
    Weather Data,            !- Actuated Component Type
    Direct Solar;              !- Actuated Component Control Type

! EMS program calling point
EnergyManagementSystem:ProgramCallingManager,
    OverrideWeatherData,       !- Name
    BeginTimestepBeforePredictor,  !- EnergyPlus Model Calling Point
    OverrideProg;           !- Program Name 1

!EMS program which sets selected weather parameters to 0
EnergyManagementSystem:Program,
    OverrideProg,           !- Name
    SET oDBT = 18,
    SET oDifSolar = 0,
    SET oDirSolar = 0;