DaylightAutonomy Extension

Introduction

Being autonomous in Daylighting means that the space does not need artificial light to perform the activities in that space.

Daylight Autonomy indicator is defined as the percentage of occupied time per year during which a sufficient level of illuminance can be maintained only with natural light.

This indicator is obtained by hour-by-hour calculation of the illuminance in a model using climatic data, taking into account the geographical position and annual weather data.

The indicator of daylight autonomy is used to describe on the one hand the performance of the daylighting as it is defined by a minimum illuminance to maintain and secondly the electric energy consumption required to maintain this minimum.
The analysis of daylight autonomy is based on the assumption that when natural light is no longer sufficient, the artificial lighting is on. The calculation is done according to a minimum threshold of illuminance, usually 300 or 500 lux, measured on the work plan, and hours of use of the building.

DL-Light extension daylight autonomy DA Sketchup model snapshot image

Daylight autonomy calculations affect thermal and lighting strategies:


Calculation of the Daylight Autonomy or BREEAM indicator

The extension allows the calculation of the daylight autonomy according to three modes:


How To Use DaylightAutonomy Extension

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

  2. Open Daylight Autonomy dialog from toolbar da dialog icon or menu option Extensions -> De Luminae -> Daylight Autonomy -> Daylight Autonomy Calculation and enter the parameters of the calculation.

    "Daylight Autonomy" mode

    DL-Light extension daylight autonomy DA General tab

    "UDI" mode

    DL-Light extension daylight autonomy DA 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 extension daylight autonomy DA Materials tab
    DL-Light extension daylight autonomy DA 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. Palette of false colours can be defined with precision. 3 options for palette are given, Automatic, Gradient and Custom:

    DL-Light extension daylight autonomy DA Panel tab
    DL-Light extension daylight autonomy DA Panel tab
  5. After all data are entered in DA dialog, select one or few surfaces and press Render Selection or run_selected button.

    DL-Light extension daylight autonomy DA 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 will is opened.

    DL-Light extension daylight autonomy DA Sketchup result imported - automatic palette
  7. Results analysis.

  8. For further calculations in the same model:

    Since version 8.0, DL-Light uses a calculation cache algorithm. It automatically detects if a surface requires recalculation or if a previous result can be reused. By default, the cache keeps the information of the last 10 calculations (value configurable in the preferences).

    For example if a calculation has just been made for the "summer" season, then the season is changed to "winter" for a recalculation, and finally recalculated for "summer":

  9. Archiving results:

    DL-Light allows to archive all the results of a calculation: reports, textures and calculation steps (exported Radiance model, weather file, ...). This archive can be reloaded on the model, subject to to use exactly the same model as when calculating.

    See the page Archiving results for more informations about this feature.

    See the page Comparison of results for more informations about comparison of several archives.

  10. Snapshots:

    Current SketchUp model view with imported results can be exported with palette snapshot_with_palette_icon or without palette snapshot_icon to png format. To explore created images user can open folder where they are saved open_snapshot_folder_icon.
    This option is not supported in trial version of the extension (see licence information).

    DL-Light extension daylight autonomy DA Sketchup model snapshot image