DGNB Extension

Introduction

The DGNB (Deutsche Gesellschaft für Nachhaltiges Bauen) assessment is based on 7 indicators (source DGNB soc 1.4 Visual Comfort):

• KPI 1 Daylight factor (DF) for 50% of the usable area
• KPI 2 Relative annual useful exposure
• KPI 3 Proportion of the roof surface area represented by translucent skylights
• KPI 4 Proportion of the rooms with direct visual link to the outside
• KPI 5 Artificial light qualities: Colour rendering index, illuminance and rate of adjustment, light colour
• KPI 6 Colour rendering index of the glazing
• KPI 7 Durations of exposure to daylight (17th January and at the equinox) and proportion of rooms to which this information applies

In DL-Light, KPI 1 can be addressed with the Daylight Factor module, KPI 4 can be addressed with the "Vision Angle to the Outside" module, KPI 7 can be addressed with the Lux module.

The module we call DGNB deals with KPI 2 "Relative Annual Useful Exposure" .

The principle of this indicator is close to that of daylight autonomy.

It introduces a few specificities:

• For a given point and for a given hour, the indicator determines whether the natural light illuminance is higher or lower than a defined value (known as the maintenance value) generally set at 300 lux. The module allows you to choose this value.
• From the calculation of illuminance, the "Relative Annual Useful Lighting" (HNutz) indicator is calculated.
• The values are defined for each point then for each space and these values are compared to the requirements of the standard.
• Work planes are defined in accordance with the standard at 0.85m from the floor.
• The grid of points on the work plane is proposed by default in accordance with standards EN12464, EN17037 and EN12193. This can be changed according to needs.
• The calculation period is also defined by default in compliance (from January 1st to December 31st from 8:00 AM to 6:00 PM).
• Acceptability thresholds are also defined directly in the color palette (>=45%, >=60% and >=75%).

Calculation of the Relative Annual Useful Exposure indicator for DGNB

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

• a "Relative" mode (which corresponds to DGNB requirements),
• a "Lux" mode which directly gives the illuminance values.

User Guide for the DGNB Extension

1. Open the SketchUp model. Consult these recommendations to prepare the model.

2. Open the DGNB window from the toolbar or the menu Extensions -> De Luminae -> Daylight Autonomy -> Activate the extension and enter the calculation parameters.

   There are 2 calculation modes in the module:

   • A relative mode which corresponds directly to the calculation requested in the standard and displays the results according to the levels required by the standard.

     "Relative" Mode

     
   • A Lux mode which displays the luminance levels for the same calculation parameters. This mode allows for graphical analysis of the results, particularly when searching for improvement paths.

     "Lux" Mode

     

   Meaning of the fields:

   • Project name - Name used for exports and output files. The SketchUp model name is used by default.

   • Results - Directory in which the model is exported for calculations.
     When calculations are started, the model geometry and result files are placed in the sub-directory dgnb_output .
     For SketchUp projects stored on a network drive (Windows), see the page Working on a copy of the model .

   • Analysis - Selection of the calculation mode:

     • Choose "Relative" or "Lux",

   • Spaces - Selection of the Em level to reach:

     
     
     For a DGNB calculation, the illuminance to be maintained depends on the type of space considered. Here it is possible to define an Em that applies by default to all spaces of the building you wish to calculate, with the exception of surfaces indicated in "Exceptions" and for which you can define a different Em.
     • The selected Em applies by default to all spaces in the model.
     • To give a different Em to a particular space, click on the "Exceptions" button to the right of the list, select a surface of the model, and choose the type of Em for this surface.
     
     Par exemple, si le bâtiment étudié est une école, il peut y avoir des dizaines de salles de classe et quelques autres espaces comme la restauration. Définir le Em par défaut, toutes les salles de classe auront ce type, et définir ensuite le Em particulier de l'espace de restauration.

   • Details - Models may require different sensor densities. The level of detail of the results and the calculation time are directly related to the sensor density on the surface to be calculated. A large unobstructed surface may require a lower sensor density while a smaller surface but with complex obstructions may require a higher density.

     DL-Light allows you to choose:

     • the sensor grid applicable by default to all calculated surfaces,
     • different sensor grids for certain surfaces ("exceptions" button).
     

     See the page sensor selection for more information on the proposed sensor choices.

   • Ground reflection - Percentage of ground reflection, determines the amount of light reflected by the ground toward the model. Select a value from the list or enter a custom value in the window:

     
     

   • Location - Building location coordinates. This information is used in combination with weather data to generate a correct sky distribution. The location can be that of the SketchUp model, that of the weather file, or a custom location (see window below).

     

   • Weather - Selection of a weather file near the site in Energy Plus format . The weather file can be selected from the list provided by DL-Light or be downloaded from the Internet. See weather data for more details.

   • Time zone - Display of the time zone used for calculations.

     The time zone is defined by the chosen climatic data file.
     Note: when a model is located in SketchUp, SketchUp proposes a time zone based on the longitude of the location. This value is sometimes incorrect, especially in Europe or Asia.

   • Period - DGNB is normally calculated over the year, but for specific analyses a period can be chosen:

     • Seasons, year - Select a season or the year. The results will be aggregated for the chosen period.

       Season dates correspond to the northern hemisphere by default. Advanced settings allow for modifying seasons. See definition of seasons in DL-Light .

     • Custom - Define the period by start and end dates.

       Full days - occupancy range from 0:00 to 23:59 over the day interval (end date included). Click on the entry area and choose the date from the calendar, or enter it directly.

       

3. Material definition.

   Each surface of the project interacts with daylight due to the optical characteristics of its surface material. It is therefore essential to assign the correct material to each surface. Material characteristics are reflectance and visible transmittance. DL-Light works by layers: a material is attached to a layer and all surfaces of that layer then use that material.

   The material selection tab:

   

   The Materials panel consists of two main parts:

   • The layer list , with for each line the layer name and the potential attached material. If the text is grayed out, the layer is hidden in SketchUp. The table is updated in real time when the SketchUp model is modified.
   • The list of available materials , sorted by libraries. The Model_materials library contains the materials currently used in the model. It is possible to modify or add materials to the list provided by DL-Light.
     To explore materials in detail, see the material manager .

   To attach a material to a layer, select one or more layers in the list, select a material and click on "Attach/Detach" .
   Changes can be canceled all at once with the "Previous" button.

4. The false color palette is precisely configurable. 3 palette options are offered: Automatic, Gradient, and Custom.

   
   • The automatic palette is generated from the calculation results in order to obtain a balanced distribution of colors. This is the best option at the beginning of a project study.
   • The gradient palette allows for global operations on the palette from minimum and maximum values, the number of thresholds and the start and end colors. This option is useful when the range of results is known. It allows for quick testing of color ranges.
   • The custom palette allows for full control over the palette. It can be used for the final rendering or to highlight particular areas.

5. After entering the parameters, select one or more surfaces and click on calculate or on the toolbar to start the calculation.

   

   Calculation time depends on the model size, its complexity, and the number of sensors.

6. When the calculation is complete, the results are imported into SketchUp. The selected surfaces receive a false color texture and the palette is displayed.

   

7. Analysis of results.

   • The report window displays the distribution of results on the palette and a summary of calculation parameters.

     

   • Show/Hide sensors allows reading the individual values of sensors directly on the surfaces.

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

8. Performing new calculations on the model.

   • To calculate a new surface, select it and click Calculate .
   • It is possible to modify calculation parameters: change sensor density to improve result visualization (for the whole model or a specific surface), modify the color palette, change the period... Regardless of the change, use the Calculate button. Previously calculated surfaces will be updated with the new parameters.

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

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

   • the system will redo the calculation for all surfaces for the "winter" season, but some steps can be avoided: calculation of sensor locations, preparation of the weather file.
   • When the "summer" season is requested again, all data can be restored from the cache, and the "calculation" only takes a few seconds.

9. Archiving results.

   DL-Light allows archiving all results of a calculation: reports, textures, and calculation steps (model radiance exports, weather file, ...). This archive can be reloaded onto the model, provided that exactly the same model used during the calculation is used.

   Consult the page Archiving results for more information on this feature.

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

   See the page Comparison of results for more information on archive comparison.

10. Snapshot.

    To create an image of the current view with the calculation results, click on for an image with the palette, or on for an image without the palette. The export directory for these snapshots can be opened with .
    This option is not supported in the evaluation version (see License information ).