Daylighting Calculations

DesignBuilder provides 3 types of daylighting calculations:

 

  1. Daylight illuminance distribution under static sky conditions with reports on average daylight factor, uniformity etc. Data is generated for each zone calculated using the Radiance ray-tracing simulation engine. Standard reports detailing eligibility for LEED EQ8.1, BREEAM HEA 01, Green Star IEQ4 and LEED v4 Daylighting BD+C credits Option 2 daylighting credits are provided. Navigate to the Daylighting screen and the Illuminance tab to view these daylighting results.

  2. Annual Climate Based Daylight Modelling (CBDM) through the Radiance simulation engine. Standard reports are generated for LEED v4 Daylighting BD+C credits Option 1 as well as general sDA, ASE and UDI distribution plots and summary reports.

  3. Daylighting integrated within EnergyPlus simulations allowing savings in electric lighting to be calculated based hour-by-hour on daylight availability throughout the year.

 

The rest of this section covers the detailed Radiance methods of calculation of daylight.

Model Data Used in Radiance

For both the Radiance static illuminance and annual/CBDM calculations, the DesignBuilder uses the following data from the model:

 

 

For Annual daylighting only:

 

 

Additional data entered on the Calculation options dialog is used to define the details of the calculation and, in the case of static illuminance calculations, some further information on the sky light distribution is provided. The above data is passed to the simulation engine which calculates the distribution of illuminance on the working plane using a backward ray-tracing method. This is done either for single static points in time (static illuminance) or over the course of the whole year (Annual/CBDM). Once the calculations have been carried out, the daylight data can be displayed in a range of formats.