LightingWestern OhioDayton

Cedar Cliff Gymnasium Lighting Upgrade 2019

Both gyms at Cedar Cliff Schools in Cedarville are relit with LED: 56 new linear high bay fixtures in the high school gym and 24 in the middle school gym, every one with a lens and wire guard. Prodigy removed and disposed of the old fixtures, ballasts and lamps, installed the fixtures the district approved, and prepared the DP&L utility rebate paperwork on the district's behalf as part of the contract.

Gym lighting is something a district lives with long past the point of liking it. The fixtures are high up, relamping means a lift and a closed gym, and the room is essentially either on or off. Cedar Cliff Schools replaced the lot in one project at its Cedarville, Ohio campus — 56 fixtures in the high school gym and 24 in the middle school gym.

The old fixtures came out and were disposed of, ballasts and bulbs included, and LED linear high bays went up in their place. Every one carries a lens and a wire guard, which in a gymnasium is not an accessory. The district approved the fixture selection before it was ordered, so what went in was what the people who use the rooms had signed off on.

The other half of the contract is administrative. Prodigy prepared the DP&L utility rebate paperwork on the district's behalf as a line in the scope of work. A rebate on a lighting retrofit is real money to a district, and it is also a form, a deadline and a set of fixture specifications that have to match what is actually hanging in the room. Writing it into the contract is how it gets claimed rather than discussed.

The result is two rooms on one fixture type, with lenses and guards suited to what happens in them, and a rebate submitted by the people who know what was installed. The work was procured under the authority of Ohio Revised Code Section 9.48.

New LED fixtures over the Cedar Cliff gymnasium with championship banners

Cedar Cliff gym from center court after the lighting upgrade

Upgraded gymnasium lighting above the student section at Cedar Cliff

Technical Discussion

Linear high bays, lenses and wire guards: lighting a gym for play

A gym can be bright and still be hard to play in. The player looking up for a rebound or tracking a serve is looking straight into the fixtures, and the two numbers that matter are how much light reaches the floor and how evenly it arrives. Cedar Cliff's high school gym took 56 LED linear high bays and the middle school gym took 24, each with a lens and a wire guard, and those three choices all answer the same question.

Bar chart of common Illuminating Engineering Society lighting targets for indoor basketball: about 30 footcandles for recreation and practice, 50 for high school competition with brightest-to-darkest uniformity of about 3 to 1, and 80 or more for large crowds or broadcast. — Figure 1 — The target for a high school competition gym is about 50 footcandles, evenly delivered.

How much light, and how even

The Illuminating Engineering Society sorts sports lighting into classes by level of play. For indoor basketball the usual targets are about 30 footcandles for recreational and practice use, 50 for high school competition, and 80 and up where there are large crowds or broadcast. Evenness is measured as the ratio of the brightest point on the floor to the darkest, and high school play is generally designed to hold that ratio at 3 to 1 or tighter. A floor that averages 50 footcandles with dark corners plays worse than one that averages 40 with none.

Why linear instead of round

A round high bay puts all of its output through a disc about a foot across. A linear high bay spreads the same output over a body several feet long. The light on the floor can be identical, but the brightness of the fixture itself, which is what a player sees when looking up, is much lower on the linear fixture. The longer body also throws a wider, softer pattern, so rows of fixtures overlap and the floor evens out at a practical mounting height. That is how 56 fixtures cover a high school court without hot spots under each one.

What the lens and the guard are for

A bare LED board is a grid of very bright points. The lens diffuses them into one luminous surface, which cuts glare again and hides the individual diodes from a camera. The wire guard is there because a gym fixture spends its life in range of a volleyball. A guard costs little and protects the lens, and the lens protects the diodes. The fixtures were approved by the district before they were ordered, which is the point at which light level, color and glare can still be changed for free.

When a gym lighting quote arrives, ask for the photometric layout, not the fixture count. It shows the average footcandles and the maximum-to-minimum ratio on your floor, and those two numbers tell you whether the gym will play well.

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