How to prepare SketchUp model for DL-Light calculation?

Introduction

DL-Light provides tools for calculation of physically based daylight indicators for SketchUp models. To get accurate results with DL-Light, we recommend that you prepare your SketchUp models:

• Work on a copy of the model
• Simplify and clean model
• Organize model by layers
• Create virtual surfaces for calculation on group/component entities
• Set model location
• Adjust surfaces orientation

Work on a copy of the model

It is recommended to work on a copy of your original model, since you may need it in future for some other calculations or presentations. Make a copy of model and do all DL-Light related actions in this copy.

On Windows operating system, we recommend to place the project directory on a local hard drive.

Simplify and clean model

DL-Light calculations are based on validated ray-tracing software Radiance. They calculate daylight indicators in sensors on selected surfaces. To avoid unnecessary calculation time, simplification steps are useful, though not compulsary.
Some cleaning steps you can use:

• Remove or hide geometry that does not impact the indicators you are calculating. Depending on extension and model you can remove:
  • Distant buildings - if you are calculating data for a single building. Keep visible onl the builidings that may have impact on daylight.
  • Furniture and interior geometry - if you are calculating indicators only on external building surfaces (eg. SE or SVF)
• Minimize ground plane surface. Overall model size has effect on calculation time. Since ground plane is usually the biggest surface in the model, make it as small as possible.
• Remove collinear points. Collinear points exist when an edge is composed of several segments. This can cause wrong export, and import of false color materials. To clean model use one of next tools:
  • Fredo Tools : Remove Lonely Vertex will show all problematic vertex in the model, and remove them on user request.
  • CleanUp³: Repair split edges will remove problematic vertices, but without any user interaction.
  • Manual model cleaning may be required for surfaces if automatic cleaning did not solve the problem. For problematic surface(s), find edges that are composed of more than one part. Delete edge lines and draw a single line instead (put line Layer to be the same as face layer).

Organize model in SketchUp layers

The organization by layer is necessary for modules that make use of materials property, like Daylight Factor, Daylight Autonomy or Watt. Material properties are attached to layers, so all the faces of a layer will get the same material.

Every face in SketchUp can have layer and material defined.
Materials in SU are used for representation purposes, but are not suitable for physically based calculations.
Layers are much better option, since all faces with the same layer can be treated as they have the same physical characteristics. Eg put in one layer objects that would be made of glass, in another layer objects made of aluminum, then wood etc.
DL-Light only exports SketchUp geometry by layers.

Recommended procedure for organizing the model by layers:

1. Switch to ‘Color by layer’: Window -> Default Tray - > Layers -> Color by layer
2. Remove unused layers: Window -> Default Tray - > Layers -> Purge
3. Create layers for various real-world materials and then attach them to appropriate objects. Note that in SU it is possible to have a group/component in one layer and nested faces in different layers. Only layers attached to faces are taken into account
   You can use:
   • Double-click to open each group
   • Select all its surfaces
   • Set layer for selected surfaces
   To check if surfaces in your model have correct layer:
   • Open DL-Light ‘Select by Layer’ dialog
   • In the dialog Select layers one by one.
   • For each layer check if correct surfaces are selected in the model

Create virtual surfaces

Detailed info on when and why are virtual surfaces may be necessary for calculations is given on page Creation of virtual surfaces.

Two cases when virtual surfaces are necessary:

• Calculation for surfaces inside group/component entities
  SketchUp entities that are nested inside groups and components, are in fact saved in model only once and then instanced over the model. Since each of these surfaces is not unique, DL-Light cannot attach to it unique id and perform calculation. As a result, after calculation on faces from groups/components, the same false color results are imported on multiple faces in model.
  To solve this problem, we avoid calculating on the surface itself and use virtual surfaces.
• Calculation on workplanes
  Some Daylighting labels, require calculation on a workplane that is offset from floor surface. This surface is virtual, and consists only of sensors. Creation of virtual surfaces provides location for sensors and won't interfere with existing building geometry.

Adjust surfaces orientation

To be able to calculate any daylight indicator, it is necessary for light to fall on the surface. Face orientation is important, since front side of the surface is receiving the light. Recommendations below are only for surfaces which are used for calculation:

• External surfaces (eg. facades, roof, glazing) should be oriented towards the outside of the building. They are usually used for SE, SVF and Watt calculations.
• Internal surfaces (eg, walls, floors, ceiling) should be oriented towards inside of the building. Usually used for DF and DA calculations.
• Horizontal virtual surfaces (eg. workplanes) should be oriented upwards. Usually used for DF and DA calculations.
• Other virtual surfaces (eg. for components entities) should be oriented depending on indicator and position inside/outside of the space.

How to activate an extension

All extensions developed by De Luminae can be used in the same SketchUp model, with restriction that only one can be active at a time. This approach is used to avoid mixing results across various daylight indicators.

When SketchUp is started, De Luminae extensions are inactive and user can work on model geometry normally.
Use menus or toolbar buttons to activate an extension. If another De Luminae extension is already in use, a confirmation is required.
When extension selection is confirmed, the user interface and all the results for previously active extension are hidden. Then the interface and results for newly selected extension are shown. The results for deactivated extension are not deleted, and will be shown when extension is reactivated.

When a new model is created or an existing model is opened, no extension results are visible until an extension is activated.

De Luminae extensions can be deactivated at any moment with click on toolbar button