DESIGN: Parameters

Orientation

Orientation is an important variable affecting energy performance in a building. Building orientation will have impacts on the building's heating, cooling, and lighting, as well as relating it to the natural environment in terms of access to daylight, ventilation and views. Differences in annual electricity use between orientations are driven by solar gain affecting cooling and daylight affecting electric lighting. Depending on the climate, certain low-E coatings will allow or reject the solar heat gain through the glazing system. In a cold climate this passive solar gain may be desired while in a hot climate it is not.

This sun path diagram of Chicago illustrates how the path of the sun changes throughout a year. The angle of the sun is much higher in the summer months and lower in the winter.

Orientation, in combination with window area and the type of glass, also affects the amount of light that can enter a space. Appropriate levels of light entering a space may result in the reduction in the use of electric lighting. This is usually achieved by using a glazing system with a high visible transmittance. Glare issues need to be considered.

In most climates, a southern orientation is preferred due to the ability to shade the summer sun to reduce unwanted solar gain while still capturing daylight to reduce the lighting energy load. The angle of the summer sun is much higher while the angle of the sun in the winter is lower which allows the light and heat to possibly enter the space. Light-redirecting strategies, such as light shelves, work well on a south facade.

North oriented facades receive good ambient and indirect daylight. Solar heat gain, too much direct light, and glare issues are minimized. In colder climates, possible heat loss through the window unit should be considered.

Due to low sun angles, glare and increased solar heat gain is harder to control on the east and west facades.

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