Active Daylighting
Encyclopedia
Active daylighting is a system of collecting sunlight using a mechanical device to increase the efficiency of light collection for a given lighting purpose. Active daylighting systems are different from passive daylighting
systems in that passive systems are stationary and do not actively follow or track the sun.
, and open loop solar tracking systems.
Closed loop systems track the sun by relying on a set of lens
or sensors with a limited field of view, directed at the sun, and are fully illuminated by sunlight at all times. As the sun moves, it begins to shade one or more sensors, which the system detect and activates motors or actuators to move the device back into a position where all sensors are once again equally illuminated.
Open loop systems track the sun without physically following the sun via sensors (although sensors may be used for calibration). These systems typically employ electronic logic which controls device motors or actuators to follow the sun based on a mathematical formula. This formula is typically a pre-programmed sun path chart, detailing where the sun will be at a given latitude and at a given date and time for each day.
Passive Daylighting
Passive daylighting is a system of both: collecting sunlight using static, non-moving, and non-tracking systems such as Windows, Sliding glass doors, most skylights, light tubes, and reflecting the collected daylight deeper inside with elements such as light shelves...
systems in that passive systems are stationary and do not actively follow or track the sun.
Types of active daylighting control systems
There are two types of active daylighting control systems: closed loop solar trackingSolar tracker
A solar tracker is a generic term used to describe devices that orient various payloads toward the sun. Payloads can be photovoltaic panels, reflectors, lenses or other optical devices....
, and open loop solar tracking systems.
Closed loop systems track the sun by relying on a set of lens
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
or sensors with a limited field of view, directed at the sun, and are fully illuminated by sunlight at all times. As the sun moves, it begins to shade one or more sensors, which the system detect and activates motors or actuators to move the device back into a position where all sensors are once again equally illuminated.
Open loop systems track the sun without physically following the sun via sensors (although sensors may be used for calibration). These systems typically employ electronic logic which controls device motors or actuators to follow the sun based on a mathematical formula. This formula is typically a pre-programmed sun path chart, detailing where the sun will be at a given latitude and at a given date and time for each day.
Companies or products that utilize active daylighting systems
- Himawari Daylight Collector
- Heliostats
- Sunflower CorporationSunflower CorporationSunflower Corporation is a start-up company founded in 2004 and based in Boulder Colorado, USA. Sunflower develops natural daylighting technology for use in commercial spaces....
- Ciralight Sun-Tracking Smart Skylights http://www.Ciralightglobal.com
See also
- HeliostatHeliostatA heliostat is a device that includes a mirror, usually a plane mirror, which turns so as to keep reflecting sunlight toward a predetermined target, compensating for the sun's apparent motions in the sky. The target may be a physical object, distant from the heliostat, or a direction in space...
- Solar trackerSolar trackerA solar tracker is a generic term used to describe devices that orient various payloads toward the sun. Payloads can be photovoltaic panels, reflectors, lenses or other optical devices....
- DaylightingDaylightingDaylighting is the practice of placing windows or other openings and reflective surfaces so that during the day natural light provides effective internal lighting. Particular attention is given to daylighting while designing a building when the aim is to maximize visual comfort or to reduce energy...
- Daylight factorDaylight factorA daylight factor is the ratio of internal light level to external light level and is defined as follows:where,Ei = illumiance due to daylight at a point on the indoors working plane,...
- Passive daylightingPassive DaylightingPassive daylighting is a system of both: collecting sunlight using static, non-moving, and non-tracking systems such as Windows, Sliding glass doors, most skylights, light tubes, and reflecting the collected daylight deeper inside with elements such as light shelves...