SketchUp to Revit to Solar Study

House solar radiation study
House solar radiation study

Expanding on yesterday’s post, I wanted to try out how I could take a building shell model that I originally created in SketchUp, take it into Revit 2010 and run a solar analysis on it using Autodesk’s new Solar Radiation Technology Preview for Revit Architecture and Revit MEP (download it from Autodesk Labs). And guess what… it worked pretty seamlessly. Here are my steps:

Revit has had a problem for a while loading the latest SketchUp file format. This isn’t different in 2010, so first the SketchUp model has to be saved to version 6 format. It is also a good idea to delete all unused geometry and simplify geometry as much as possible. Less faces means less calculations. It might also help to align the project correctly already in SketchUp. This way, you can use Google Earth to do that and you don’t have to work with Project North in Revit (although that has become much easier to use in the release, too).

The process of getting a SketchUp model into Revit is the same as always (however, with 2010 it still seems to take a bit longer until I finally find the menu button I was looking for). First you have to go to the massing tab and create a new in-place mass. Then, in the family editor, go to the insert tab and insert a CAD file (the SketchUp file). That’s it! Almost…

House and shading objects separated

To speed calculations, it is a good idea to remove “shading-only” objects (like the trees and the neighboring houses) from the calculation. You do that by entering “shade” into the comments section of any object just before you export to the technology preview. In my case, I copied the mass over itself and then removed the house from one mass and the shading objects from the other mass. This way, I could easily enter the comment on one of them (see image below). What is really handy in this release of Revit is that a partial explode of the imported SketchUp data actually explodes it to the SketchUp component level.

Preselecting shading elements using the word “shade”

Once the model is prepared, just go to the Add-on tab in Revit and start the add-on. It comes with a nice help file that explains everything well. For my calculations, I also maximized the mesh for greater accuracy. Here are a few results:

Solar distribution over the roof areas
Solar distribution over the roof areas
Averaged values
Averaged values

The only odd behavior that I noticed was that the calculation result shading appeared to change with the view angle (compare both images above). This is not very helpful when colors are to be matched against values. However, overall this is a very useful tool.

By the way: Here is an example of the “classic” solar study in Revit:

“Classic” Revit solar study – spring equinox from Alexander Schreyer on Vimeo.

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