How is solar orientation carried out?
By simple repositioning of the architectural long side to the south and the short sides to the east and west, the site will get solar heat in winter thus reducing heating bills. In addition, it will block heat in summer to save on air conditioning costs. Thus, benefits are both monetary and environmental. It is optimum to let a home directly face the sun; a nominal curve up to 30 degrees due south has the same effect, with a loss of only 5 percent of the potential savings. Additionally, windows and the wall in the south can be shaded from the summer sun by an overhanging roof.
Good solar orientation also helps to cut down on cooling costs by reducing wall and window area facing the low-angle sun. The west-facing windows are responsible for a major part of overheating during summer, spring, and fall. East and west windows also receive solar heat when the sun rises and sets.
Limiting the west-facing window area and choosing window features that reduce heat gain without reducing visibility or light transmission makes good orientation sense. Windows and patio doors having a Solar Heat Gain Coefficient (SHGC) less than 0.6 on west-facing walls is known to be good. Visible light transmission of 40-50 percent is necessary.
What factors influence solar orientation?
Orientation is subject to planning. The structural repositioning costs—for example, the cost of building additional windows—are quite small. Physical constraints like steep land, shadows of other houses and trees, etc. can be worked around with the 30-degree flexibility rule. No major structural changes are needed, though moving windows to the south will enhance solar performance. Once the south-facing window area touches 8-10 percent of the floor area, the home can be called 'sun tempered.'
Most building plots are adaptable to solar site design. A little extra effort ensures worthwhile benefits by adding another dimension to a home's comfort and efficiency.
