daylightharvesting

Daylightharvesting refers to the practice of maximizing the use of natural daylight to illuminate indoor spaces and, in some cases, outdoor areas, with the goal of reducing dependence on artificial lighting. It involves architectural design, daylight-responsive control systems, and devices that capture, transmit, or diffuse daylight.

Historically, daylighting has roots in passive solar design and architectural optimization. Its modern form, often called daylight harvesting, gained prominence during energy crises of the 1970s and 1980s and has since evolved with advances in glazing, shading, sensors, and lighting controls.

Techniques fall into passive and active categories. Passive daylighting includes thoughtful orientation, window placement, skylights, light shelves, atria, and reflective interior surfaces that distribute daylight deeper into spaces. Active daylighting uses sensors and dimming controls that adjust electric lighting in response to available daylight, sometimes combined with occupancy sensing and automated shading.

Key metrics for evaluating daylighting performance include the daylight factor, daylight autonomy, continuous daylight autonomy, and useful daylight illuminance. These measures help assess whether spaces meet illuminance goals while minimizing energy use.

Benefits of daylightharvesting include reduced electricity consumption, lower peak demand, and potential improvements in occupant comfort and productivity. Drawbacks can include glare, excessive solar heat gain, higher initial costs, and complex design and maintenance requirements.

Successful implementation depends on climate, building type, and regulatory standards. It is commonly addressed in green building programs such as LEED daylighting credits and WELL certification, and is supported by tools like daylight simulations and lighting controls standards.