The PEC Heliodon
Over the years, heliodons or "sun machines" have been built in a variety of configurations. In each case, the device creates the appropriate geometrical relationship between an architectural scale model and a representation of the sun. By allowing adjustment for solar declination (season), the earth's rotation (time of day), and site location (latitude) a heliodon can simulate sunlight penetration and shading for any combination of site location and time. The result is a representation of solar patterns for clear sky conditions. Other techniques are often used in concert with heliodon simulations to account for variations in the strength of the sun (due to weather, angle of incidence, and atmospheric attenuation) and local horizon shading. Heliodons provide an effective tool for the visualization and calculation of solar effects at the window, building, or site scale.
The fixed-sun, moving-earth heliodon demonstrates the actual motion of the earth relative to the sun. In our design, the moving-earth table has a prominent north pole-south pole axis that tilts toward and away from the fixed-sun for seasonal variation. The whole upper part of the heliodon rotates on the north pole-south pole axis to adjust for time of day. The table top also tilts to adjust for site latitude. Click here for more information on the PEC heliodon.