Two very important goals of today’s sustainable design movement are to maximize energy efficiency and create high indoor environmental quality. One excellent place to initiate an effort to meet these goals is the building’s lighting.
From a sustainable perspective, the objective of a lighting system is to create an interior with comforting light and ample illumination for tasks through minimal energy use.

To achieve this objective, a lighting system needs to be more than just a group of light fixtures – it must also include the room’s ceiling system and other interior surfaces, which can play a large role in light distribution. The proper co-ordination of light fixtures with ceiling systems is therefore an important part of a sustainable interior lighting design strategy.

Co-ordinating Ceilings With Light Fixtures

By properly co-ordinating the ceiling system and other surfaces with lighting fixtures, interior designers can create a more pleasant and energy-efficient interior environment. This design concept is often times referred to as daylighting. Daylighting, as it refers to ceilings, is an effort to extend the rays of the sun to augment the lighting in a building’s interior. A common tactic of today’s sustainable design movement, daylighting decreases the need for electric light and enhances building occupant comfort by connecting occupants to the world outside.

Daylighting strategies can lead to significant energy savings for the building owners. The savings, though, will vary, as the actual reduction of lighting will be dependent on a detailed evaluation normally provided by the lighting consultant. This evaluation will take into consideration the location and the exposure and height of windows at the perimeter of the space. In addition, the light fixture type and its output in lumens will figure prominently into the calculation. However, it is certain that the capacity to design with fewer fixtures and to take maximum advantage of extending daylight farther into the working space is enhanced by the integration of high-performance lighting with a highly reflective acoustic ceiling capable of distributing natural light throughout the interior space.

Selecting ceiling panels with a flat, bright, white surface that are low in texture is a good strategy for achieving higher light reflectance. In addition, when selecting a ceiling panel, interior designers should check the ceiling panels light reflectance value (LR), which represents the percentage of light reflected from the surface of a material. The average light reflectance for ceiling panels is typically .80 or less. Panels with LR values above .83 are generally considered high-performance.

With regard to the light fixtures themselves, it is wise to consider those with sensors, which dim the electric lighting whenever the natural light is present at prescribed levels in the interior space.

Light Fixture-Ceiling Panel Combinations

Interior designers can co-ordinate flat, white-surfaced ceiling panels with a variety of energy-efficient, dimmable light fixtures to facilitate ideal daylighting results. Indirect lighting is often a better choice for luminaires when coupled with a high LR ceiling. This combination more effectively addresses issues such as glare and diffusion, with regard to natural and artificial light. Daylight can provide required ambient lighting for most operating hours. However, it is necessary to provide user-controlled task lights to assure that ample task illumination is available at all locations when supplemental lighting is deemed necessary. Users near windows will often use daylight as their primary task source for most of the working day – except, of course, during periods of overcast weather.

Conclusion

A successful energy-efficient lighting system is the sum of all its parts and how well they work together. Designers who allow light fixtures and reflective ceiling panels to work together can create a beautiful, pleasant interior environment, with happier, more productive occupants. This combined with energy savings make proper ceiling and light co-ordination a great way to kill two birds with one stone.

Robert L. Marshall is the manager of marketing technical services for CertainTeed Ceilings Corp. Marshall has more than 30 years of experience in contracting, distribution, and manufacturing of acoustic ceilings and can be contacted at <robert.l.marshall@saint-gobain.com>.