Door Operation

Openings tab in model data under Doors

The operation of doors can be defined by entering data under Operation headers:

• % Area door opens - defines the area of the door which opens relative to the total area to give an approximation of the actual opening size and,
• % Time door is open - defines the average time the door is in the open position.  Accounts for the fact that during occupied periods the door may open and close repeatedly. The average effect

The way this data is used depends on the Natural ventilation model option set:

Calculated

The average door opening size used in the simulation is calculated by multiplying the % Area door opens by the % Time the door is open by the gross door area. A schedule can be applied to control timing of the opening.

The ventilation rate through the door opening is calculated based on the wind and stack pressure effects.

Scheduled

External door opening is not modelled explicitly with the Scheduled natural ventilation model data setting. Instead, the total natural ventilation flow rate and operation is defined for each zone on the HVAC tab. No operation data is entered on the Openings tab for external doors.

Internal doors are modelled using the EnergyPlus 'Mixing' object which mixes air between the two adjacent zones.  DesignBuilder uses a very approximate empirical relationship to calculate the mixing flow:

Flow (m3/s) = Door area (m2) * % area door opens * % time door is open * Farea-flow

where Farea-flow is a factor used to obtain the mixing flow from the opening area = 0.1.

A schedule can be applied to control timing of the mixing flow..