Because the Sun Emulator uses seven rings to simulate the 21st day of all twelve months, the heliodon is a 3-D model of the sun paths. At an instant, one can tell that the sun comes only from a part of the sky often called the solar window. It is also easy to see which region of the sky the sun shines from during the overheated period, which region of the sky in the underheated, and equally important which region of the sky the sun never shines from. It is also easy to show how these regions of the sky move up and down with changes in latitude. It is most important to understand that any specific sun angles are not very meaningful and potentially misleading. For example, June 21 at 12 noon is not representative of the summer condition although frequently used in graphical approaches to solar design. Rather, it is very important to understand that the sun must be rejected whenever it comes from the summer region of the sky. The size of this region is a function of climate. Similarly, the sun angle of Dec. 21, 12 noon is not especially meaningful because we want to collect the sun when it is coming from the winter region of the sky.

By rotating the cradle holding the rings, it is easy to understand how to design a solar responsive building anywhere from the equator to the poles. It is instantly obvious, for example, that at the equator, north and south windows receive equal amounts of sun over a year. Thus the Sun Emulator is a powerful teaching tool even before its lights are turned on.

The Sun Emulator clearly shows not only the daily symmetry of the sun’s travels across the sky but also the annual symmetry where the sun path for Nov. 21 is the same as Jan. 21 and May 21 is the same as July 21, etc. It is for this reason that only 7 rings (sun paths) are needed to simulate the 12 months. This heliodon also shows how for six months of the year the sun shines into north windows at all latitudes even if it is only for brief times and at very glancing angles. Most people, including many "solar designers”, erroneously believe that the sun never shines into north windows or that it only occurs for a few days. For hot climates this fact is of great importance. It is also easy to understand how the length of day is a function of not only time of year but also latitude, except of course, for the two days each year called the equinoxes. All this can be understood within minutes by any person, of any age, and any educational level.

Unlike graphical, verbal, or mathematical explanations, learning from a "conceptually clear” heliodon is easy, quick, leaves a profound understanding, and will be retained far better because it does not depend on rote memory but on a god’s-eye — view experience of the relationships of a building with its constantly changing solar environment.