Daylighting

Daylighting is the practice of using natural light to illuminate interior spaces. It encompasses the design of windows, skylights, and other openings, as well as reflective surfaces and diffusing elements to distribute daylight. The aim is to provide adequate, visually comfortable illumination while reducing reliance on artificial lighting.

Design strategies include orienting buildings to maximize daylight, sizing and shaping fenestrations, and using devices such as light shelves, clerestories, and skylights. Shading systems, screens, and louvers control glare and seasonal solar gain. Interior finishes and reflective surfaces improve daylight distribution, while daylighting controls and sensors enable dimming of artificial lighting as daylight levels change.

Benefits include reduced energy consumption for lighting and cooling, lower peak electrical demand, and improved occupant comfort and productivity. Daylight can support circadian rhythms and well-being when daylight distribution is balanced and glare is minimized. Uncontrolled daylight, however, can cause glare, overheating, and uneven illumination.

Challenges include maintaining consistent daylight under variable weather and with urban constraints. Solar heat gain can increase cooling loads in warm climates, while shading devices add complexity and cost. Maintenance of glazing, blinds, and sensors is also a consideration.

Performance is evaluated with metrics such as daylight factor, daylight autonomy, and useful daylight illuminance. Tools for daylight simulation and measurement support design decisions, and standards and guidelines in codes and sustainability rating systems set targets for daylight performance.

Daylighting is applied in residential, commercial, educational, and public buildings, and is a core element of sustainable design. It works best when combined with other passive strategies and, where appropriate, with active energy systems to create comfortable, energy-efficient spaces.