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Timing model Option

Data tab on Model Options dialog.

You can specify schedules in DesignBuilder using two approaches:

• Typical workday - where the timing is defined by a start time, end time, working days per week and seasonal variation. This approach is intended for easy early stage modelling of non-domestic buildings.
  
  
• Schedules - where Schedules can either be defined for each day of the week and each month of the year using daily Profiles or by using Compact Schedule format. Schedules are more flexible and can be used in other projects but they take longer to set up.

Generally if you start to find the Typical workday timing mode too restrictive you should switch to Schedules mode.

You can also request:

Timing HVAC + natural ventilation operates with occupancy

Select this option if all heating, cooling, natural ventilation and DHW operation follows occupancy.

This option is only available if Timing is set to Typical workday.

Note that HVAC operation data can modify the HVAC operation even when Timing HVAC + natural ventilation operates with occupancy is set. For example:

• Simple HVAC - Mechanical ventilation, Heating and Cooling operation have additional Days / week and seasonal operation data. Heating operation also has Preheat hours and Cooling operation also has Precool hours.
  
  
• Compact HVAC:
  
  
  • Fan-coil units, Unitary single zone - Mechanical ventilation, Heating and Cooling operation have additional Days / week and seasonal operation data. Heating operation also has Preheat hours and Cooling operation also has Precool hours.
    
    
  • VAV/CAV/Unitary multizone - Min AHU outside air, AHU heating/cooling, Zone setpoint schedules have additional Days / week and seasonal operation data. Heating operation also has Preheat hours and Cooling operation also has Precool hours.

These differences are applied as 'modifiers' to the basic occupancy schedule because HVAC systems generally switch on and off based on the occupancy time but with differences. e.g. Heating systems are often switched off in summer, they may operate during weekends when the building is unoccupied and they will often have a preheat period to get the building up to temperature before occupancy.

Internal gains operate with occupancy

Select this option if lighting and other internal gains operation follows occupancy. If you wish to enter specific schedules for lighting and/or other internal gains you should uncheck this option. For example there may be low levels of emergency lighting and some IT equipment usage while the building is unoccupied.