Thus, building orientation, along with daylighting and thermal mass, are crucial considerations of passive solar construction that can be incorporated into virtually any new home design.
Facts and Figures
The Sun’s True Position
Schoolchildren (and most homeowners) will tell you that the Sun rises in the east and sets in the west, and, if this were true, building orientation would be a fairly simple matter. In reality, the sun rises and sets in the east and west only on the autumnal and vernal equinoxes, and something very different happens during the remaining 363 days of the year.
The Earth’s tilt causes the Sun to rise and set slightly south of east and west in the winter, and slightly north of east and west in the summer. This slight angle depends on the time of year and the observer’s distance from the equator.
As a result, the winter sun spends all of its time in the southern sky, and the summer sun spends much of its time in the northern sky (the sun crosses over into the southern sky during part of the day, depending on latitude). In the Southern Hemisphere, these directions are reversed, so the winter sun rises and sets in the northeast and northwest, respectively, and the summer sun rises and sets in the southeast and southwest, respectively.
How the Sun’s Variations in Position Can Affect Building Design
The relative position of the Sun is a major factor in heat gain in buildings, which makes accurate orientation of the building a fundamental consideration in passive solar construction.
A rectangular house’s ridgeline should run east-west to maximize the length of the southern side, which should also incorporate several windows in its design. For this reason, fewer windows should be located on the northern side of the house where the summer sun can be intense. A deep roof overhang can shade the few windows in this area, as can different types of shade trees and bushes. Research supports an east-west ridgeline. Homes re-oriented toward the Sun with no additional solar features save between 10% and 20% and some can save up to 40% on home heating, according to the Bonneville Power Administration and the City of San Jose, California.
Builders should note that these directions are given regarding the Sun and not magnetic north, which can vary significantly from the Sun’s actual position. Magnetic north, as read from a compass, can still be used as a reference if the builder adjusts the figure based on the location-specific magnetic variation, which can be found in publicly available maps.
Building Tips for New Construction
The following tips will also assist homeowners and builders in maximizing heat gain through building orientation:
Ultimately, factors such as street appeal and the property’s lot dimensions may restrict a builder’s ability to orient a building in strict accordance with passive solar techniques. Even while working under these constraints, however, a builder can still create an energy-efficient home through implementing energy-saving features, such as low-E windows, adequate insulation, air sealing, and cool roofs.
In summary, homes oriented to the path of the Sun with require less energy for heating and cooling, resulting in lower energy bills and increased indoor comfort. Homeowners who are considering new builds should consult a Columbus Advanced Inspections home inspector who can meet with them and their builder to discuss ways to maximize low-cost and no-cost energy strategies.