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8.3 Daylighting

This part of the Energy Efficiency Manual lowers the cost of lighting by exploiting sunlight for illumination. It shows how to provide daylighting to the extent that it is practical with current materials and equipment. Daylighting is much easier to accomplish well if it is designed into new buildings. You will learn how to exploit daylighting in new construction, how to retrofit it to existing buildings, and how to salvage defective daylighting installations in existing buildings.

The amount of sunlight falling on a building, even on a cloudy day, is theoretically sufficient to provide all the building’s lighting requirements. The practical challenge is distributing sunlight throughout the building. Daylighting is already an important method of saving energy in large, open buildings, such as warehouse and factories. It can save lighting energy in the perimeter spaces of most other types of buildings.

New methods and equipment are needed to approach the full potential of daylighting in all buildings. A serious obstacle to daylighting is a lack of effective methods for distributing sunlight throughout the building. Here you will learn to make the best use of skylights, light pipes, light shelves, sun trackers, and interior colors and finishes for distributing daylight. Using diffusers to improve light distribution is explained.

Daylighting is a complicated source of illumination. This makes daylighting design exceptionally complex, a fact that is not yet recognized adequately. Daylighting has major interactions with heating, cooling, electric lighting, and the building structure. Daylighting must be integrated with control of solar gain, with passive solar heating, with control of artificial lighting, and with the esthetic aspects of architectural design.