> For the complete documentation index, see [llms.txt](https://docs.ladybug.tools/hb-radiance-primer/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.ladybug.tools/hb-radiance-primer/components/3_recipes/daylight_factor.md).

# Daylight Factor

![](/files/-MihqhsFW6xRbehL5bch)

![](/files/-Ma9XT8oWfouAArsQuoW) - [\[source code\]](https://github.com/ladybug-tools/honeybee-grasshopper-radiance/blob/master/honeybee_grasshopper_radiance/src//HB%20Daylight%20Factor.py)

Run a daylight factor study for a Honeybee model.

Daylight Factor (DF) is defined as the ratio of the indoor daylight illuminance to outdoor illuminance under an unobstructed overcast sky. It is expressed as a percentage between 0 and 100.

Because daylight factor is computed using an overcast sky, it does not change with \[North, East, South, West] orientation. As such, it is more suited to assessing daylight in climates where cloudy conditions are common. The "HB Annual Daylight" recipe yields a much more accurate assessment of daylight and is suitable for all climates, though it requires a significantly longer calculation time than Daylight Factor.

### Inputs

* #### model \[Required]

A Honeybee Model for which Daylight Factor will be simulated. Note that this model should have grids assigned to it in order to produce meaningfule results.

* #### grid\_filter

Text for a grid identifer or a pattern to filter the sensor grids of the model that are simulated. For instance, `first_floor_*` will simulate only the sensor grids that have an identifier that starts with `first_floor_`. By default, all grids in the model will be simulated.

* #### radiance\_par

Text for the radiance parameters to be used for ray tracing. (Default: -ab 2 -aa 0.1 -ad 2048 -ar 64).

* #### run\_settings

Settings from the "HB Recipe Settings" component that specify how the recipe should be run. This can also be a text string of recipe settings.

* #### run \[Required]

Set to True to run the recipe and get results. This input can also be the integer "2" to run the recipe silently.

### Outputs

* #### report

Reports, errors, warnings, etc.

* #### results

The daylight factor values from the simulation in percent. Each value is for a different sensor of the grid. These can be plugged into the "LB Spatial Heatmap" component along with meshes of the sensor grids to visualize results.