Calculation of BREEAM Daylight Factor requirements

Introduction

The BREEAM agency has developed a certification method for buildings sustainability. BREEAM publishes requirements that building projects should meet to get a sustainability certification.

Among the various requirements, a number of them are grouped in a category called "HEA 01 Visual Comfort". Visual comfort requires evaluation of the 3 criteria:

The DL-light Daylight Factor extension allows you to calculate these indicators directly inside SketchUp.

As it is based on the same process as classic DF calculation, we recommend that you get familiar with it: Daylight Factor calculation.

We will not go in depth in the definitions of these criteria. For details about them, we recommend that you check the abundant documentation provided by BREEAM.


Principle of calculation

The requirements are based on the following calculations:

The general procedure is complex and DL-Light provides a simple interface to perform these calculations and explore results.

Note

"The uniformity ratio calculation, minimum point daylight factor and minimum daylight illuminance can exclude areas within 0.5m of walls. Areas within 0.5m are not regarded as part of the working plane for this purpose, although they are included in the average daylight factor and average daylight illuminance calculations. BREEAM


How to calculate BREEAM Daylight Factor requirements

  1. Open SketchUp model. Follow next instructions to prepare your model for DL-Light calculations.

  2. Open DaylightFactor dialog from toolbar df_dialog_icon or menu option Extensions -> De Luminae -> Daylight Factor -> Daylight Factor Calculation and enter the parameters of the calculation.

    DL-Light DaylightFactor Extension DF BREEAM General tab
    DL-Light DaylightFactor Extension DF BREEAM General tab

    Fields description:

  3. Define materials characheristics.

    Since calculation is done with verified Radiance tools it is necessary to 'attach' physically based material to each layer in SketchUp. Note that materials should be defined with their solar reflectance and transmittance.

    The tab of choice of materials:

    DL-Light DaylightFactor Extension DF BREEAM Materials tab
    DL-Light DaylightFactor Extension DF BREEAM Materials tab

    Materials panel consists of two main parts:

    To attach a material, select in the table layer(s) and either double-click on required material in the tree or select the material in the tree and press Attach/Detach button.
    To detach from the layer(s), select it and click Attach/Detach button.
    To revert all layers to previous state press Revert button.

  4. The false color palette is updated for BREEAM requirements.
    The 4 default colors allow a readable display directly in the SketchUp model.

    DL-Light DaylightFactor Extension DF BREEAM Panel tab
    DL-Light DaylightFactor Extension DF BREEAM Panel tab
  5. After all data are entered in DF dialog, select one or few surfaces and press Render or run_selected button.

    DL-Light DaylightFactor Extension DF BREEAM Sketchup selection

    Calculation time depends on number of selected surfaces, level of sensors details and model's complexity.

  6. When results are imported, selected surface will have appropriate false colors and Palette is opened.

    DL-Light DaylightFactor Extension DF BREEAM result
  7. Results analysis.