Daylight Harvesting Reduces Lighting Costs

By: Daintree Networks  11-11-2011
Keywords: Reduce Energy, Energy Commission

The concept of daylight harvesting (also called daylighting) is simple. During the day, when natural light is streaming in through windows and skylights, less artificial light is necessary. Automated daylighting systems detect daylight levels by using photosensors, and automatically dim or brighten electric lights as required to reach a consistent lighting level throughout the day.

Making more use of natural light helps to consume less energy, which reduces both energy costs and carbon footprint. The California Energy Commission estimates that daylight harvesting can reduce energy costs by 5–15%.

Luminaires that are dimmed or turned off typically emit less heat, which helps to reduce air conditioning costs. Dimming can also extend the life of a lamp, helping to further reduce costs (and landfill). And studies show that people prefer natural to electric light, daylighting helps to make building occupants happier. 

Automating daylight harvesting 

A number of automated daylight harvesting solutions are available, consisting of dimmable luminaires or ballasts, photosensors, and lighting (or building) control software. 

The sensors have a photoelectric "eye" that measures the illumination in a specified zone. They transmit this information to the control software, which is programmed with acceptable threshold levels. If the illumination levels fall outside those thresholds, the software sends commands to dim or brighten the luminaires as required. 

It is possible to implement pseudo-daylight harvesting that uses timers to dim and brighten luminaires at the same time every day, but this is a less satisfactory solution. Timers are not able to take into account things like whether the sky is clear or overcast, or whether people have closed the window coverings to reduce heat and glare, so often result in inappropriate levels of illumination. 

Daintree's daylight harvesting solutions 

Daintree Networks enables advanced daylight harvesting that is easy to implement, monitor and maintain, by using a combination of wireless photosensors and ballasts, and intelligent control software.

Daintree provides a simple user interface to set up and manage illumination threshold and lamp brightness levels. Manual over-ride can be offered, allowing occupants to brighten (or dim) pre-set levels when they are performing tasks that require more (or less) illumination.

Daylight harvesting can also be conbined with other cost-saving strategies, such as scheduling and occupancy control, to further add to savings.

Keywords: Energy Commission, Reduce Energy

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