Below is my contribution to the August issue of tED Magazine on the topic of sports lighting. Reprinted with permission.
Since 2000, an average 60 percent of Americans have identified themselves as a sports fan, according to Gallup. In 2016, U.S. construction spending on amusement and recreation facilities (not including those built as part of educational facilities) increased nearly 10 percent to about $22 billion. In regard to lighting, new and renovated facilities are a juncture of venerable best practice, robust regulation and new technology.
In 2015, the Illuminating Engineering Society (IES) published an update to RP-6, Sports and Recreational Area Lighting. RP-6 states, “The goal of lighting for sports is to provide an appropriate luminous environment that contributes to the visibility of the playing target (ball), the competitors and the surrounding backgrounds.” Put another way, sports lighting should deliver optimal light levels and visual comfort for play and spectating.
Achieving this goal requires addressing quantity of illumination, or providing minimum maintained horizontal and/or vertical light levels. It also requires addressing quality of illumination, which incorporates a range of factors such as uniformity, glare, modeling and color quality. Care should be taken to minimize light trespass and skyglow in outdoor installations as dark-sky communities continue to grow across the U.S. Finally, selecting efficient luminaires, avoiding overlighting and using lighting controls can achieve good lighting while minimizing energy consumption.
Recommendations are geared by venue, sport and classification of play. Venues include both indoor and outdoor spaces—arenas, covered stadiums, athletic fields, field houses, gymnasiums and pools. Sports include aerial (e.g., baseball, basketball, football) and ground level (e.g., hockey, boxing, skating). Classification of play includes Class I (competition play with 5,000+ spectators), Class II (competition play with up to 5,000 spectators), Class III (competition play with up to 2,000 spectators) and Class IV (competition or recreational play with limited or no spectators). Some facilities are used for different sports and classifications of play, and therefore should be able to address the requirements of all uses.
Class I facilities, of course, impose the most complex requirements. Not only do these facilities have special design requirements, often broadcasting is involved. Sports organizations and/or broadcasters may impose detailed lighting requirements regulating everything from light levels to color.
Let’s look at a football field as an example. This sport is multidirectional, combining aerial and ground play. Typical lighting includes aimable floodlights mounted on crossarms fixed on poles. For nighttime play on a Class I field, IES recommends 100 footcandles (fc) of maintained horizontal illumination, measured or calculated 3 ft. above the field on a 30-ft. x 30-ft. grid. It is important the light distribute uniformly across the playing area. The Uniformity Ratio (UR), expressed as a ratio between the highest and lowest calculated or measured light level values, should be 1.7:1 or less. The Coefficient of Variation (CV), which expresses a weighted average of all light level values, should be 0.13 or less.
These recommendations become less stringent for other classifications: 50 fc, 2:1 or less UR, and 0.17 or less CV for Class II; 30 fc, 2.5:1 or less UR, and 0.21 or less CV for Class III; and 20 fc, 3:1 or less UR, and 0.25 or less CV for Class IV.
Continuing our example, luminaires are often mounted on poles typically varying in quantity as four, six or eight poles. These poles commonly install along the sides of the football field behind the bleachers to ensure clear spectator views. With larger setbacks, more luminaires and taller poles may be necessary.
Floodlights should be aimed out of the players’ line of sight to avoid direct glare. Each floodlight’s beam spread should place the highest quantity of its light output on the field without producing a “hot spot,” and with coverage overlapping the distribution of adjacent luminaires. A range of beam spreads is available, with luminaires typically designated as Beam Type 1-7 based on the NEMA sports luminaire classification system. This system is being challenged by LED luminaires, which offer the ability to precisely tailor beam spread based on the application.
An eight-pole configuration might include four on each side, inset 30 ft. from each end (around the 0-yard line), spaced 100 ft. apart and set back 15 to 45 ft. A six-pole configuration might include three on each side, inset 30 ft., spaced 150 ft. apart and set back 45-74 ft. A four-pole configuration might include two on each side, inset 90 ft., spaced 180 ft. apart and set back over 75 ft. Major stadiums may see installation of floodlights in four lighting towers (one at each corner) or mounted on architecture such as an overhead steel truss system.
For a 160-ft.-wide standard football field, a setback of 30 ft. would typically entail a mounting height (measured from ground to the bottom of the floodlight crossarm) of 50 ft., according to IES. For a 50-ft. setback, a 60-ft. mounting height. For an 80-ft. setback, an 80-ft. mounting height.
Equipment should be selected appropriate to the application requirements. Light output, beam spread, shielding, color quality, ease of maintenance, energy efficiency, aiming, ingress protection and other factors must be evaluated based on the application. As with other applications, LED technology offers some significant advantages and is being rapidly adopted; in 2015 and 2017, the Super Bowl was played under LED lighting. Notable benefits include significant energy savings, longer life, spectral tuning, controllability (including dynamic events such as halftime shows), and optical options enabling superior glare control and a wide range of beam spreads. Another advantage is instant-ON operation, a critical consideration in resuming play after a power interruption, particularly during televised events. During the 2013 Super Bowl at the Mercedes-Benz Superdome, the stadium went partially dark, delaying play for about a half hour on account of the metal halide luminaires taking time to resume full brightness after power was restored. In 2016, the Superdome upgraded to a new LED system.
Sports lighting is one of the more complex but rewarding lighting markets, imposing varying requirements based on type of play, venue and classification. As such, it pays to become educated about the basics and new product offerings so as to recommend and select appropriate solutions.