Clerestory Windows and Passive Solar Design

Clerestory Windows

Taking their inspiration from the high windows used to illuminate the giant halls of classic European churches and cathedrals, clerestory (pronounced clear-story) windows can be used in a green home design to increase daylight and passive solar energy to rooms.

Clerestory windows are a row of windows above eye level in a room, usually installed higher than adjoining roofs, that allow daylight deep into a space without compromising privacy like standard windows can.

Clerestory windows can greatly reduce or eliminate the need for electrical lighting during the day, and can also be used to provide cross-ventilation in a home, reducing air conditioning costs. In a natural process known as a "thermal siphon", which is based on the natural convection of hot air rising, Clerestory Windows can play an extremely important role in the evacuation of hot air that would otherwise be captured by the living space.

Increasing Daylight with Increasing Heat Gain with Clerestory Windows

Clerestory windows can greatly increase the amount of sunlight entering a space, but the possibility of overheating that space needs to be addressed. Clerestory windows can be installed with awnings or under roof overhangs to reduce heat gain. Clerestory windows can also be placed on north-facing sides of the house where they won't be exposed to as much direct sunlight.

In instances where capturing the sun's heat is important during the colder winter months, clerestory windows should be installed on the home's south side to maximize heat gain. Including a low-emissivity coating on south-facing windows will reduce heat loss. Installing south-facing clerestory windows with awnings, under roof overhangs, or with natural shading like trees, will minimize overheating during the warmer summer months when the sun is at a higher angle in the sky.

Clerestory windows' high placement on a house can also help keep inside temperatures down by capturing cool summer breezes, providing a cross-ventilating element to the home's passive solar design.

Clerestory Windows in a Green Home Design

In addition to contributing to energy savings, clerestory windows can also add very attractive architectural detail to a well-designed green home. Clerestory windows should be considered as a crucial component to an efficient green home.

Advantages that Clerestory Windows Have Over Roof Windows and Skylights:

• Less likelihood of water leakage problems
• Less Ice Buildup on Roof
• Easier to Ventilate Roof and Attic Spaces
• Easier to Ventilate Interior Spaces and Shield Rain