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Bringing the benefits of daylight indoors

'Daylight harvesting' balances natural and artificial illumination.


September 30, 2019
By Graeme Doggart
Daylight harvestingPhoto courtesy Signify.

Light contributes to a sense of well-being in any building, but especially those that lack natural daylight. Changing patterns of ambient lighting can help people feel connected with the world outside, so they are able to stay alert and focused. At the same time, harvesting daylight can help save electricity and thus reduce utility bills.

‘Daylight harvesting’ is the process of balancing both natural and artificial light to obtain the desired level of illumination. In the simple example of a parking lot, for example, a photocell control turns artificial lights on when it is dark out and keeps them off during the day, when they would be unnecessary and a waste of energy. The approach can be taken indoors, as well, which is particularly advantageous when surrounded by other buildings that block sunlight.

Further, it can be a manual or automated process. Traditionally, indoor lighting has been turned on and off manually by occupants, at the flick of a wall switch near a space’s entryway. The addition of dimmers enabled greater control over light levels.

Dimmers allow for ‘scaled’ daylight harvesting, where an occupant can theoretically dim lighting output anywhere from 100% to 0%, which can be effective for saving energy. From an operations standpoint, however, it is troublesome to constantly change artificial light levels manually throughout the day to compensate for the changing amount of natural light (which is affected by time of day, time of year, weather and cloud coverage).

This is where LED lighting control systems come in. By collecting data from embedded sensors and communicating it across the Internet of Things (IoT), they can better optimize operations with energy savings in mind.

First, the sensors capture how much natural light is entering a given space. Then, the corresponding control system can increase or reduce the amount of artificial light, so as to achieve or maintain a minimum recommended light level.

Using the same data, schedules can be set to ensure artificial lights are only powered during the times they are required. Motion sensors, meanwhile, can ensure lights are only on when a space is actually being used. Light level ‘scenes’ can even be customized as appropriate for different tasks throughout a building.

This is not so say manual daylight harvesting has no place in a modern building. Indeed, occupants can be granted access to the lighting control system, allowing them to adjust levels to their personal preference, rather than to a predetermined threshold. If they do not need as much light as assumed, then this access can reduce energy consumption even further, as well as personalize the environment for the occupant.

We now have more control over indoor light levels than ever before. Advances in IoT technology allow us to create smart workspaces, with light points capturing important data, providing new insights and, as a result, increasing energy efficiency.

Graeme Doggart is a marketing manager for the Canadian operations of Signify, formerly known as Philips Lighting, which develops Interact Pro lighting control systems with daylight harvesting and other features. For more information, visit www.signify.com.