Daylight tab

The Daylight tab is used to configure and launch daylight simulations within IDA ICE. It is divided into four main sections:

• Calculation Settings
• Optical Properties
• Measuring Planes
• Results

This page provides a general overview of the Daylight tab, with a focus on the Optical Properties and Measuring Planes sections, which are common to all calculation types.

For detailed information about the Calculation Settings and Results specific to each daylight method, please refer to the corresponding documentation pages (Daylight factor, Point-in-time Illuminance and Climate-based daylight).

Calculation settings

Three different types of daylight calculation are available from the Calculation Settings section:

• Daylight factor 
• Point-in-time Illuminance 
• Climate-based daylight

After selecting one of the available daylight simulation methods, you can configure the parameters of the simulation in this section. Depending on the chosen calculation type, you may be able to adjust parameters such as:

• Sky type (e.g., clear, overcast, or climate-based),
• Precision settings, and
• Shading and occupancy controls.

Where applicable, these parameters can be customized to suit the needs of the specific daylight analysis. Note that the available options and their effects vary depending on the selected calculation method. For more detailed guidance, please refer to the documentation page for each method (Daylight factor, Point-in-time Illuminance and Climate-based daylight). There is additional information regarding the 

Once a daylight simulation has been performed, the timestamp of the last simulation will be displayed in the "Simulated" column of the table. To manage the simulation results, click the arrow button  next to the corresponding row. This will open a context menu with the following options:

• Report: Opens the daylight report, which includes detailed results and diagrams.
• Animate: Launches a visual animation of daylight in the 3D tab.
• Remove: Deletes the simulation results for the selected entry.

Optical properties

The Optical properties table displays the surface properties of all geometry relevant to daylight calculations. It provides a centralized interface to view and edit the optical characteristics used in simulations.

Within the table, you can:

• Set surface properties directly by editing the values in the cells.
• Load surface material from a database (derived from Bodart et al., 2008).
• Copy and paste cell contents for efficient editing across rows or columns.
• Open detailed surface properties by double-clicking the object name in the leftmost column.
• Sort the table by clicking on any column header.
• Visualize a property in the 3D view by clicking the box icon  in the corresponding column header.
• Export the table to Excel for external editing or record-keeping.

Window limitations: Transmittance and reflectance are calculated only for windows that lie between two zones or between a zone and the exterior. Windows that do not meet these conditions are excluded from daylight calculations.

Shading objects properties: For shading objects with transparency defined either in the 3D view or via imported geometry, the effective reflectance used in daylight calculations is adjusted based on the transparency value (T). Specifically, Effective Reflectance = Surface Reflectance × (1 – T). This adjustment ensures that the daylight model correctly accounts for the partially transmissive nature of materials like mesh fabrics or perforated panels.

Description of the table:

Measuring planes

Daylight is evaluated on measuring planes, which are virtual surfaces where illuminance levels are calculated.

Horizontal surface inside zones

To automatically generate measuring planes within zones:

1. Tick the checkbox for "Horizontal surface inside zone."
2. Click the "+" button to select the zones where daylight calculations should be performed.

3. A measuring plane will be created for each selected zone using the following user-defined parameters:

   • Height above floor
   • Offset distance from walls
   • Grid resolution (distance between measuring points)

This is the standard method for evaluating daylight across workplane height in rooms.

User-defined measuring planes

You can also define custom measuring planes directly within the 3D view, either on the building body or inside a zone:

1. Open the relevant wall or object in the 3D view.
2. Insert a measuring plane from the palette.
3. In the table, use the "Active" checkbox to include or exclude specific measuring planes from the daylight simulation.

This method is ideal for evaluating vertical illuminance, external surfaces, or non-standard locations.

Run simulation

The Run button, located at the bottom left of the Daylight tab, starts the daylight simulation based on the current configuration. The simulation is performed using:

• The selected zones or measuring planes,
• The calculation settings, and
• The optical properties defined in this tab.

In the Expert Edition, simulations for multiple zones and measuring planes are distributed and executed in parallel, utilizing the number of processors specified under: Options > Preferences > General > Simulation.

For Climate-based daylight simulation, Linux-version of Radiance™ executables can be used instead of Windows-version executables (default) by selecting the corresponding option in Options > Preferences > General > Simulation.

In order to be able to use this option, Windows Subsystem for Linux (WSL) must be installed on the system. Check Microsoft Windows WSL page for more information about how to install and use WSL. If the option is ticked but WSL is not detected by IDA ICE the default Window-version executables will be used instead.

Results

After the simulation is completed, a range of scalar daylight metrics is displayed in the Results table.

• Use the radio buttons above the table to switch between Daylight Factor, Illuminance and Climate-based daylight results.
• When Illuminance is selected, a second row of radio buttons appears, allowing you to choose the specific time point for which results are displayed.

Within the table, you can:

• Select and copy individual cells to paste into other applications,
• Sort the data by clicking on a column header,
• Visualize a result in the 3D view by clicking the box icon  in the column header, and
• Export the entire table to Excel.

For a detailed explanation of the available metrics – including how they are calculated, their units, and how to interpret them – please refer to the documentation page for the specific daylight simulation method used (Daylight Factor, Point-in-Time Illuminance, or Climate-Based Daylight).