DaylightAutonomy (EN 17037) Extension

Introduction

The EN 17037 standard (in UK: BS EN 17037:2018 Daylight in buildings) proposes in paragraph B.3.3 a “method 2” for measuring the amount of natural light in a space. This method corresponds to a daylight autonomy type calculation:

• Use of an annual climate data file,
• the illuminance on the fraction of the reference plane must be achieved for 2190 hours (50% of the surface for the target illuminance, 95% for the minimum target).

This extension is designed to follow the recommendations of the original standard:

• Reference plane at 0.85m from the ground,
• display of results for the median target, the minimum target or the synthesis,
• use of the sensor grid defined by the standard,
• palette of 4 colors corresponding to the high / medium / minimum criteria defined in the standard. We add a "dark" label to show the surfaces below minimum level.
• taking into account the criteria related to the supply of natural light by vertical, inclined and horizontal openings.

For the UK variant using the "UK National Annex", see Daylight Autonomy (EN 17037/UK)

As this computation is based on the same process as the others daylight autonomy calculations in DL-Light, we recommend that you get familiar with daylight autonomy calculations.

How To Use DaylightAutonomy (EN 17037) Extension

1. Open the SketchUp model. Follow recommendations to prepare your model for DL-Light calculations.

2. Open DaylightAutonomy (EN 17037) dialog from toolbar or menu option Extensions -> De Luminae -> DaylightAutonomy (EN 17037) -> Activate extension and enter the parameters of the calculation.

   

   Fields description:

   • Project name - The project name is used during export and for output filename generation. The SketchUp model name is used by default.

   • Results - The directory where model will be exported for calculation.
     When calculation is started the model geometry and the resulting files will be saved in daylightautonomy_17037_output subdirectory.
     For SketchUp projects stored on network disk (Windows), see see Work on a copy of the model.

   • Mode - Calculation mode selection:

     • Synthesis: the surface validates the high level, median or minimal if it meets the criteria for this level for both the median and minimum target thresholds.
     • Target: the surface validates the high, medium or minimum level if:
       • for lighting by a vertical source, 50% of the reference plane receives the corresponding illuminance (750 lux / 500 lux / 300 lux),
       • for lighting by a horizontal source (opening in the ceiling), 95% of the reference plane receives the corresponding illuminance (750 lux / 500 lux / 300 lux).
     • Minimum target: the surface validates the high, medium or minimum level if 95% of the reference plane receives the corresponding illuminance (500 lux / 300 lux / 100 lux). The minimum target is only applicable for illumination by a vertical / inclined source.
     Nota: To determine the percentage of surface reaching a threshold, the default setting is to consider that each sensor represents the same portion of the surface. The surface ratio is therefore the ratio of the number of sensors, this is the strict interpretation of the standard. Conversely, the standard DA calculation assigns to each sensor a weight proportional to its coverage area. See "Coverage area of sensors" in preferences.

   • Horizontal source - Selection of surfaces whose illumination is mainly due to a horizontal light source. The "Surfaces" button opens a window displaying the list of horizontally lit surfaces. Click on a surface of the model to add it to the list, click on the red cross to remove it.

     Only the surfaces of this list have the horizontal lighting criterion. The surfaces selected for the calculation and not listed in this group are considered as lit by a vertical light source (general case).

     

   • Details - The default selection is the EN 17037 grid required by the standard:

     • Distance between sensors of 0.5 × 5^log10(d) meters, where d is the longest dimension of space if the length / width ratio is between 0.5 and 2, otherwise the smallest dimension,
     • The surface of the mesh excludes a strip of 0.50m along the walls, the grid is calculated on this reduced surface.
     The EN 17037 grid is very sparse compared to the usual sensor grids. For example, the density of sensors is more than 6 times lower than the density of the EN 12464-1 grid. The selection of a different grid is possible to allow a more detailed study of the daylight autonomy values ​​on the surface.
     • the sensor grid applicable by default to all calculated surfaces,
     • different sensor grids for some surfaces ("Exceptions" button).
     

     See sensors selection for more information on the choices of proposed sensors.

   • Ground albedo - Reflection factor of the ground. Value can be selected from drop-down list or defined custom value in next dialog.

     
     

   • Location - Building location coordinates. Location can be based on SketchUp model location, current Weather file location or be Custom. Below is dialog for Custom location definition.

     

   • Weather - Select annual weather file for the building location in Energy Plus weather file format . The weather file can be selected in the list provided by DL-Light or downloaded from Internet. See page Weather data.

3. Define materials characheristics.

   Since calculation is done with validated 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 to choose materials:

   

   Materials panel consists of two main parts:

   • SketchUp tags (layers) table contains the list of all tags defined in the SketchUp model. Each row contains SketchUp tag (layer) name and attached material name if any. If text in a row is grayed, it means that the corresponding tag is not visible in the model. The table is updated in real time, as the SketchUp model is modified.
   • Materials tree contains all materials libraries available for DL-Light extension. Some of them are provided when extension is installed and others can be imported or created by user. Subtree 'Model materials' contains materials currently attached to SketchUp layers.
     To explore available libraries and add new ones, see Materials libraries dialog.

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

4. The palette of false colors uses the thresholds of the standard. It is possible to change the different colors.

   

5. After all data are entered in dialog, select one or few surfaces and press Render or button.

   As the glazing is kept for this calculation, it may be practical to use the DL-Light select by tag dialog to select the areas to be calculated.

   

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

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

   

   Surfaces illuminated primarily by a horizontal light source receive this watermark:

   

7. Results analysis.

   • The Report dialog displays the distribution of results over current palette, and calculation input parameters.

     Presentation of the report for the modes synthesis, target and minimum target:

     

   • Show/Hide Sensors and Values explores results directly in the model for each sensor.

     • Nota: the option "View / Guides" of SketchUp must be activated.
     

8. For further calculations in the same model:

   • To run calculation on surfaces simply select them and Render .
   • It is possible to modify the parameters of the calculation: to change the density of sensors to improve the visualization of the results (for all the model or a specific surface), to modify the palette of colors... Whatever the change, use the Render button. Previously calculated surfaces will be updated with the new settings.

   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).

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 using exactly the same model as during the calculation.

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

   • To archive the calculation results, click on the button Archive.
   • To load the results of a previous calculation, click on the button Load

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

10. Snapshots:

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