The direct light of the sun and shadows cast by it are best evaluated b
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| The Platform Heliodon simulates sun and shadow patterns in a manner reflecting the changing geometric relationships between the earth and the sun as seen from space. From this perspective the sun is relatively stationary and the earth (and table) orbits, rotates, and tilts in relationship to this “fixed” sun position. |
y carefully considering the orientation of the plan form of a building and the corresponding orientation of the apertures in its elevations and/or roofscape. It is not uncommon for many decisions about solar access to influence the basic plan form and its orientation, but response to the movement of the sun can also be accommodated through carefully detailed and properly oriented local fenestration elements including the aperture, its glazing, and associated projections for reflecting light and/or creating shade.
When placing a model on either heliodon, it is important to recognize the north arrow notation on the instrument to assure proper simulation of building behavior in response to the beam radiation from the sun.
In general, it is important to note the distinction between the daily and seasonal influences of the sun; it is helpful to think in terms of the proportionality of relationships involved. As a rule, east- and west-facing building surfaces are primarily influenced by daily conditions, morning light versus afternoon light, solar/thermal load from sunrise to noon versus solar thermal load from noon to sunset. Conversely, those building surfaces which have primary aspect to the south, are better understood as having a seasonal relationship to the sun; that is to say, the south face sees the sun all day long, and the real measure of difference in the solar influence on building geometry and interaction with elements of the building facade varies by season more than it varies by the symmetry of the sun during the day.