A set of spotlights on this two-season heliodon reproduces the position of the sun at different times of the day in summer and winter. The house rotates to demonstrate how the light will impact it depending on how the house is oriented to the sun.
This model shows how sun angles change with the seasons. The sun is low in the sky in the winter, and much higher in summer as the earth moves around the sun. It also changes position through the course of the day as the earth turns on its axis.
The design and orientation of a house (which way it faces on the compass) has a great effect on where the sun will strike it; heating unshaded rooms with its powerful light in summer, and missing beneficial heating in winter. Proper orientation can drastically reduce a house's total energy consumption.
For more information about heliodons visit our Heliodon Studies (PDF, 30 KB) fact sheet.