High Ceilings? Uplighting To Avoid The Cavern Effect

Brighten up facility occupants' day (and night) with uplighting strategies in areas with high ceilings, such as manufacturing, malls, and sports arenas .

By Tommy Harris

What do all people need to function effectively within large indoor spaces? The visual acuity and comfort that comes from evenly distributed, uniform lighting.

In large open spaces, where ceilings typically ranging from 16 to 30 feet in height, proper lighting is essential to safely performing the task at hand, whether people are operating machinery, playing basketball, or shopping.

Perception is Everything

Regardless of indoor application, lighting has a psychological impact on how people perceive the environment. Perhaps the most important element is uniformity of light within the space. Most people think of uniform lighting as what they see either on the floor or the work surface, but how the indoor space is illuminated above our heads is equally important.

A dark ceiling is commonly referred as the “cavern effect” by lighting industry professionals. In almost all cases, this is undesirable because a dark ceiling is unnatural and uncomfortable to the human eye. The human eye perceives a space to be brighter when it is lit uniformly versus when it is forced to perceive dark and light contrast.

Adding intentional uplight in the range of 7-14% is the most effective way to eliminate the cavern effect. (Photo: Acuity Lighting)

Adding intentional uplight in the range of 7-14% is the most effective way to eliminate the cavern effect. Even today, this is difficult to accomplish with LEDs that by design are directionally focused. A few manufacturers have taken on this challenge, developing fixtures that provide intentional uplight. The best performing fixtures include two LED sources to light above and below the fixture to reduce the visual contrast between the source and the ceiling. The method helps eliminate dark ceilings.

Easy to See, Easy to Enjoy. By properly illuminating the entire structure, from the floor to the ceiling, uplight reduces the perceived glare so the eye doesn’t have to work as hard. The illuminated luminaires more easily blend into the surroundings which reduces the contrast that can lead to eye strain. This can lead to a safer and more noticeably enjoyable environment.

More for Less. With traditional lighting technology, it was not uncommon for lighting to account for up to 60% of a building’s energy bill. With lighting and control solutions available now, facility management can significantly reduce energy consumption — and uniformly distributed uplight can contribute greatly.

As mentioned above, uplight makes a space appear to be brighter, allowing for those luminaires to be dimmed to a perceived light level that is acceptable for the task being performed. This is often referred to as “task tuning” and is easily accomplished with the correct commercial/industrial LED lighting and control system for the application. The typical wattage reduction from task tuning is greater than 20% compared to the wattage consumed at full power.

Lighting Becomes Both Functional and Flexible. Along with task tuning, LED luminaires can benefit from time-based scheduling for known operating hours, photocells that allow for dimming when natural light is present, and group zoning to support facilities with changing needs. This is easily accomplished by connecting each LED luminaire to a networked lighting control system that will allow them to be controlled individually or as an entire group.

The perceived and actual benefits of uplighting are clear for facility managers of large spaces: uplighting is a safe, uniform, and efficient way to light spaces that are notoriously challenging to illuminate. It is now time to brighten up everyone’s day — and night.

Harris is the vice president, industrial product marketing with Acuity Brands, a North American market leader in commercial and industrial lighting.