Draw Hole


For details of using the Draw hole tool, please refer to the Draw window tool.


Holes are usually used for two purposes:


  1. For merging zones together. Note that the Merge zones connected by holes option must be selected for this to work.
  2. If adjacent zones aren't merged then holes between them allow air and radiation to pass. See below for details on this.


Holes can also be added in exterior surfaces to allow air and radiation to pass.


Tip: It is possible to draw large holes in surfaces to give the effect of the surface having being removed. This can be a useful technique for creating atrium-type spaces, connecting gable roof blocks to the main roof block and generally merging zones in different blocks.

More information on Drawing holes can be found in the Basic Drawing Tools 7 Tutorial


The way holes are modelled in EnergyPlus depends on the model options selected:


The way that airflow through holes (and virtual partitions) is modelled depends on the Natural ventilation model option selection. The rules are as follows.


Scheduled Natural Ventilation and Heating and Cooling design calculations Simulations with Calculated Natural Ventilation

Holes positioned on internal partition walls are used to mix the air between the two adjacent zones, but only when using Model airflow through openings model option. In this case the airflow through internal holes is calculated based on the Airflow rate per opening area data.


External holes have no effect on airflow. This is because scheduled natural ventilation has no way to calculate the airflow through an external hole which would in reality require knowledge of wind speed and direction and other pressure-related data.

Holes simply represent a constant air flow path in the fabric and air flow through them is unaffected by natural ventilation setpoints.


The airflow through holes is calculated (using the EnergyPlus Airflow network) based the pressure difference across the opening and a coefficient of discharge of 0.65.


Radiation and conduction heat transfer

The way that radiation and conduction of heat through holes (and virtual partitions) is modelled depends on the solar distribution setting, the solution algorithm and the calculation type as described below.


All exterior holes and when Solar distribution algorithm is Full interior and exterior Internal holes in simulations when using CTF solution algorithm Internal holes in heating design and cooling design or when using Finite difference solution algorithm
Modelled as "windows" with "perfectly clear" glazing and so they transmit solar radiation and conduct heat. Modelled as Infrared Transparent surfaces in EnergyPlus. The hole will participate in the transfer of visible and solar radiation by doing a "wavelength transformation", making all short wave length radiation that is incident on the surface into long wave length radiation and having it participate in the long wavelength radiant exchange. Modelled as an opaque sub-surfaces with a standard "Holes and vents" construction, so no radiation transfer takes place between the 2 zones, only conduction plus any airflow.