Daylight Factor and Illuminance

Daylight Factor

Metrics >> Daylight Grid Based >> Daylight Factor

A daylight factor is the ratio between exterior sky illuminance on an overcast day and illuminance inside a building. To run the metric, you must have first set up a sensor node grid using the Nodes button.

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Metrics Menu: Daylight Factor

Since the sky condition is overcast, neither a sky condition nor a date and time for the calculation are needed. You have the option to manually change your Radiance parameters and the geometric density of your geometry.

Illuminance

Metrics >> Daylight Grid Based >> Point-in-Time Illuminance

Illuminance calculations are also called “point-in-time” calculations because unlike the annual, or climate-based metrics, illuminance calculations measure light levels at a specific date and time. Like Daylight Factor, you will need to set up the sensor node grid, using the Nodes button before you run this metric.

Units

Select your preferred lighting units, (Lux, Footcandles.)

Solar Date and Time

Enter a date and time for the calculation. To enter minutes use an integer followed by a decimal point. For example, if you want to run a test on September 21 at 9:15am. Enter “09 21 9.25”.