References: Plants, People & Environmental Quality: Atrium Buildings

RULES
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.