While many factors determine household energy use, one way to maximize potential savings is to include energy awareness in planning your housing site. Where your house sits on the lot in relation to the sun, wind and surrounding topography can make a difference in your heating and cooling needs and their cost. Position your house to take maximum advantage of seasonal warmth and chill throughout the year.
Sun Directions
In the Northern Hemisphere, although seasonal change can affect the sun's height in the sky, sunlight emanates from the south. The sun's apparent height in the sky can vary by as much as 50 degrees from summer to winter equinox. Knowing the sun's seasonal positions in your locale will help you to take best advantage of summer light and winter warmth.
A North-South-Facing Lot
Placement of your house is easy on a lot that faces north or south to the street. Plan your site so that the widest sides of your house also face north and south. This usually means that the ends of the roof ridge line on a rectangular house will point to the east and west. To capture the sun's light and warmth, plan to use a larger expanse of windows on the south side than the north. In climates of prolonged, excessive heat, you may prefer to expand windows on the north side of the house to benefit from indirect light. Whether you center your house on the lot or to one side will depend on other factors.
An East-West-Facing Lot
Ideally, for energy-conserving purposes, a house on an east- or west-facing lot should also have the long side facing south if possible. With the ridge line oriented east-west, this may mean that a narrow side of the house faces the street. You will need to choose between a street-facing entryway or one on the wider north- or south-facing side of the house.
Additional Building Placement Considerations
Incorporate sun-sensitive roof overhangs in your design, especially to shade interior spaces facing south and west. Place overhangs so they shield your house from heat in the summer, when the sun is higher in the sky but allow the home to capture the warmth and light of the sun when it is lower in the winter sky. Locate porches on the east and west sides of the house for further shade and interior cooling. If your lot is bordered by woodland or other tree growth, bear in mind that the shadows cast by growing trees will increase with time. Nearby deciduous trees provide summer shade and let winter light and warmth through. Evergreen shade will be year-round and can serve as a winter windbreak. When planting next to wooded land, plan minimum setbacks of between 10 and 20 feet to take best advantage of cooling shade and wind buffering.
Hills and Slopes
Choosing an energy-conserving site for your house means taking into account topographical and climate factors beyond exposure to the sun. A hilly site that requires building portions of the house on several levels will put more diffuse demands on heating and cooling systems than a flat site that accommodates a simple rectangular structure. A cleft between hills creates a narrow alley that intensifies wind strength. Steep slopes and outcroppings can also create areas of deep shade that make regulating house temperatures difficult.
Air Currents
Local wind conditions can make a difference in how you position your house for maximum energy conservation. In general, cold winter winds come from the north. Coastal breezes usually blow from offshore. On a building lot with exposure to ocean breezes from the west, backed by hills to the east, for example, design and position can work together to make the most of both sunny warmth and cool breezes. Placing the house on an east-west access lets openable west-facing windows collect offshore breeze. Paved areas, like patios, to the east and south store and reflect the sun's warmth back toward parts of the house. In the same type of lot, strong winds channeled by hills or frequent strong offshore winds suggest a layout with the long sides facing north-south, along with smaller east-west windows, to expose the house to less wind-generated heat loss.