When the sun shines, buildings receive more sunlight throughout the day than is required for lighting. However, building design limits the ability for daylight to reach the majority of spaces that are used by building occupants.
People simply prefer sunlight. Electric lighting is designed to recreate sunlight but cannot effectively match its quality and spectrum. In addition, up to 26% of all electricity in buildings is used for lighting.
Traditional Daylighting Is Limited
Two main methods are used to bring daylight into buildings. Skylights and skytubes bring natural daylight into building interiors through a glazed opening at the roof level. The challenge with this method is its limitation to single storey buildings or the top floor of a building. Skylights can also introduce glare and thermal discomfort to building occupants.
Horizontal daylighting methods are limited to the perimeter of buildings. Design strategies include: utilizing thin, rectangular floor plates oriented towards the sun to minimize sunlight penetration distance, and using high floor-to-ceiling spacing and higher viewable window spans. Designing a building for daylighting can increase construction costs and higher window-to-wall ratios generally lead to thermal heat gain/loss and uncomfortable solar glare, resulting in building occupants having to close their blinds.