Green Building Library
Daylighting

Atriums

One of the biggest advantages of an atrium is that it allows the designer to use very large floor plates.

Rule of Thumb

Toplighting

Maximize useful daylight. Minimize excessive sunlight and associated unwanted heat gains. If cloudy con-ditions prevail, use a clear, unobstructed glazed roof. If sunny conditions prevail, use shading controls. Toplit designs can be an energy liability, consider clerestory designs for added shading control.

Reflectivity

Design the atrium as a light funnel with maximum reflectivity and, hence, maximum wall area for reflection at the top. As the bottom is approached, wall area is exchanged for increasing aperture size in order to deliver light to the spaces at the bottom and to ensure that available light is balanced between the top and bottom.

Apertures

Use smaller size openings at the top and maximum openings at the bottom.

Glazing

Glazing with higher degrees of reflectivity can be used to promote downward penetration of light, although this is less effective than opaque reflecting surfaces and may not be aesthetically suitable.

Lightshelves

Can be used effectively on the upper floors, on the northern side of the atrium, where light is the brightest and most direct to compensate for smaller apertures.

Planting

Use with caution on upper levels. The low reflectivity of plant material reduces the effectiveness of a reflecting surface. The atrium floor is the best location, although it limits reflectance into adjacent spaces.

Excerpted with permission from Design Smart published by BC Hydro.