What is IES & USTA Standard on lighting?
The standards that both the United States Tennis Association (USTA) and Illuminating Engineering Society (IES) change from court to court. From the professional level down to high school tennis courts, lighting requirements change due to viewing of each requirement. The number of light poles will increase for larger stadiums and decrease for smaller venues. These groups also require lighting to be evenly spaced for the least amount of light leakage and maximum court coverage.
The IES has further provided their expert opinion on the required amount of light that is essential for tennis courts. This can be applied for either indoor or outdoor usage but is very specific to the amount of court lighting required. These are applied to professional, semi-pro levels, and high school level tennis events. The strict levels required by the USTA also advise strict recommendations for tennis court lighting based on levels of their profession. The combination of these two sets a universal standard of what the minimum lighting levels should be set at.
Foot candles
Foot candles describe the number of actual candles that would illuminate a square foot. It’s the oldest form of light measurements that is still used today. In the case of sports lighting for tennis, eyesight on the tennis ball must be clearly seen. Over the entire court surface, the average in square footage will fluctuate in foot-candle intensity. This lighting must maintain consistent coverage to allow tennis players to navigate their playing field without loss of available light.
Since lighting is essential at night, the adjusted value of foot-candles helps to simulate daylight conditions. This can be applied indoors or outdoors and will often be higher in foot-candle value for large viewing audiences. This light level is often adjusted for HDTV cameras so that professional slow-motion cameras can analyze training data later. Foot candles are later converted into Lumens which apply to the type of lighting units that are used. Many of the latest light units are replacing older lighting equipment.
Cumbersome standard lighting that was used for the last 50 years is now being replaced with high intensity LED lighting. The level of foot lighting can better be managed along with light saturation and color temperature is also improved. These are the average requirement values based on the 4 classes of tennis courts.
Class I: Professional level play- 125 foot candles
Class II: College level/challenger sport- 75-100 foot candles
Class III: High school/Private clubs- 50-75 foot candles
Class IV: Recreational- 30-50 foot candles
Lux level for tennis court lighting
The measure of Lux is an interesting comparison to what lumens represent. The easy way to describe Lux is the level of light that is needed to see something. How much light is used in the dark to see something clearly as you would see in the daytime? This is not only a matter of Lumens since Lux also provides the right ambiance for selected types of viewing. With 200 Lux being used, it allows enough light that is comfortable or slightly intimate. If this is raised to 400-500 Lux, it’s similar to the lighting you experience in office buildings and work desks.
600-750 would be perfect for surgical work and activities that require precise work activities. However, at the level of 1000-1250 Lux, you will be able to see every detail of a sports field area. Professional tennis is based on exact lighting on the court so that players can track a fast-moving ball easier. While it’s not so critical at high school levels, the amount of light used for evening play is usually relaxed. The more competitive tennis becomes, the higher the level of Lux can become. Here are the amounts of Lux used for the different class courts:
Class I: Horizontal- 1000-1250 Lux – Vertical 500 Lux
Class II: Horizontal- 600-750 Lux – Vertical 300 Lux
Class III: Horizontal- 400-500 Lux – Vertical 200 Lux
Class IV: Horizontal- 200-300 Lux – N/A
See also: How many lumens & lighting fixtures to light a tennis court?
Lighting uniformity of IES & USTA standard
This is another rate of light measurement that breaks down tennis courts into sections that are measured in light uniformity. These can be measured using a greater than equal to a formula that dictates the proper amount of light that’s used. It covers every square foot of the tennis court using a U2 (uniformity) minimum. Each section is given a uniformity rating of how light is spread and focused on the court itself. In a nutshell, a tennis court can fill dark spots that lighting is not rated so well for by adjusting lens focus.
Uniformity minimum levels are adjusted to the closest Lux rating in each square foot as a result. This helps to cover a field evenly, ensuring that tennis courts pass the requirement that IES and USTA are recommending. If these levels are met with satisfactory results, they are reported as such for the institution that is asking for a class rating for light coverage. It might sound more technical than it really is, but this accuracy is more important at professional and semi-pro levels. Here are the light uniformity levels that are needed:
Class I: ≥ 0.7 (ITF), 1.5 (USTA) rated at 700-1000 Lux
Class II: ≥ 0.7 (ITF), 1.5 (USTA) rated at 700.1000 Lux
Class III: ≥ 0.5 (ITF), 2.0 (USTA) rated at 200-400 Lux
Class IV: N/A
Glare in tennis court
Because the amount of light that’s used to cover a tennis court can be overpowering at times, direct brightness is further adjusted. This is how a glare control rating helps to mark the light that’s provided from overhead. Lighting a court will reflect on surfaces that can often be good or bad. These GR ratings determine the brightness and level of luminance that viewers and players feel comfortable with. For most lighting purposes this translates to a 1-9 grading level.
The lower the number used for GR ratings represent a higher grade level, so GRs of 90 is number one. This is considered light that’s unbearable whereas number 9 isn’t noticed at all. The best rating is middle of the road marking GR 50. This is also rated for tennis courts for professional levels as GR 50 and GR 55 for semi-professional tennis.
Class I: 50 (Using 4000K outdoors)
Class II: 50 (Using 4000K outdoors)
Class III: 55 (Using 2000K outdoors)
Class IV: N/A
Color rendering index requirement
There is one final criterion that’s also measured, which includes the CRI levels. The USTA, IES, and ITF (International Tennis Federation) all recognize these ratings for tennis CRI levels. These are measured from 0-100 going from poor to excellent conditions. These levels are also rated among spectrums that range from warm white to daylight. A high school tennis court will often have cool white CRI levels, while pro and semi-pro courts are rated at daylight spectrums.
Cool white represents cool white using a standard 2000K CRI light source. As the pro level courts, all fall into the daylight (4000K) category between 65 and 80. Here is the complete CRI rating list for their courts.
Class I: 80
Class II: 65
Class III: 60
Class IV: Not specified
