A virtual heliodon from Energy3D

The virtual heliodon of Energy3D
in action.

According to Wikipedia, "a heliodon is a device for adjusting the angle between a flat surface and a beam of light to match the angle between a horizontal plane at a specific latitude and the solar beam. Heliodons are used primarily by architects and students of architecture. By placing a model building on the heliodon’s flat surface and making adjustments to the light/surface angle, the investigator can see how the building would look in the three dimensional solar beam at various dates and times of day."

Nowadays, few architects would construct a model building and put it under a heliodon. Computer software can do a far better job in simulating the physical situations than electric light of a mechanical heliodon. A number of companies have developed virtual heliodons for daylighting design. Some of these are part of integrated CAD systems such as Autodesk's Ecotect, which are quite pricy. Now, there is a free version we just developed, which is equally good. Even better, it runs on the Web as a Java applet. And it comes with a design studio for you to create your own buildings. Imagine designing your houses online and use the virtual heliodon to check how the sun shines on them at different days and times at different locations.

You can try our heliodon applet out at this URL. Unfortunately, this applet only works on Windows at this point.