The following is not a specification for the lighting of indoor courts, because there are several ways of accomplishing desirable results in a wide variety of buildings. What is attempted is to provide Guidelines that should be considered in designing and specifying proper lighting for tennis courts.
2.0
Objectives of Proper Lighting
A.
To make it easy to see and follow a ball at the time it is tossed in the air by the server, and while it is repeatedly hit and projected at every path it follows as long as it is in play.
B.
To minimize the glare from the lighting equipment.
C.
To design a system that is economical to install, clean, maintain and operate.
Be sure to note that it is not necessary to produce illumination simulating daylight, since the quality of the light is more important.
3.0
Quality of Light
Quality of light is determined by a number of factors including uniformity of distribution, background colors and a non-glare light source.
Lighting levels should be as nearly uniform as possible within the entire playing space, including approximately 6' outside the sidelines and behind the base lines approximately 10' and/or within 10' of the back walls.
It is important to use colors that contrast with the tennis ball to a height of approximately 12' - 14' directly behind the court, high enough so that the background color is behind the ball on the service toss. Above these levels it is highly desirable to have a very light matte finish of uniform color including all structural members. On the walls adjacent to the length of the court (at the ends of the building), the contrasting colors should continue to at least the baseline of the court.
High Intensity Discharge (H.I.D.) fixtures are commonly used. Whatever the style of fixture employed, it is very important to avoid a source of high intensity concentrated in a small area visible to the player. An after-image of the light source in the player's eye causes him momentary blindness and he cannot see the ball during that time. It is important to note that some H.I.D. fixtures cause "hot spots" from components of the fixture itself and/or from being located too close to the ceiling system. When H.I.D. fixtures are pointed towards the ceiling, it is very important to incorporate a reflective ceiling system to maximize lighting performance.
If fluorescent fixtures are selected, lenses and louvers on the lighting fixtures will generally protect the eyes from excessive brightness provided that the diffusing lens is sufficiently far from the light source or the louvres are sufficiently close together. Louvres should provide a cutoff of approximately 45 degrees when looking parallel to the length of the court and 35 degrees at right angles to the length. If lenses are used, they should reduce glare. Florescent lighting is rarely used today.
Lighting can be direct, indirect or direct/indirect. Up-lighting is very important in order to see the balls that go above the light source and to reduce the contrast between the lighting above and below the lighting fixtures. In general, it is advisable to have at least 40 percent of the light go upward.
4.0
Quantity of Light
The quantity of light is important, but must be considered along with other factors. In general, 60-75 footcandles average maintained is minimum while at least 75-100 footcandles average maintained is recommended for most facilities and 125 footcandles average maintained is minimum for professional, international, national and collegiate facilities. Televised events normally require 125 maintained foot-candles, however, recent developments in camera equipment do not require this high of illumination. Television networks should be contacted to determine the required lighting levels and locations for the event in question.
Light meter readings should be taken from a point 36" above the court surface with the light sensitized cell facing upward. The reading should include a location 6' outside the alley line of the court, and 10' behind the baseline. The variance from the average to the minimum or the maximum should be no more than 25%, preferably as low as 15%.
A.
Maintained illumination is determined by applying a light loss factor (LLF) to the initial calculated or measured foot-candle illumination. LLF depends on lamp characteristics, luminaire design, voltage variations, atmospheric conditions, and dirt accumulation. It can vary from 0.6 to 0.8. Consult manufacturer’s publications for proper LLF values.
B.
Average maintained horizontal and minimum maintained horizontal illumination should be the calculated or measured and the values multiplied by the appropriate LLF.
C.
Uniformity ratio is defined as the ratio of maximum illumination divided by the minimum illumination.
D.
Primary Playing Area (PPA) is defined as an area measuring 48’ by 98’ or 6’ outside the sidelines and 10’ beyond the baselines.
5.0
Lighting Fixtures and Lamps
Lighting fixtures of nearly any type can be employed if they conform to the requirements of quantity, even distribution, low intensity of surface brightness and minimized contrast between the light source and the ceiling above. Lamps such as high-intensity discharge, fluorescent, mercury or incandescent can be used.
H.O. fluorescent lamps usually produce approximately 75 lumens per watt, have a life of approximately 18,000 hours based on 12 hours per start, and have good color rendition; the light efficiency remains high, and the lamps reach full brightness immediately. If lenses are used, they must be either non-breakable or protected against a direct hit by a tennis ball. Louvres must also be resistant to bending from a direct ball hit by means of close spacing of reinforcement or by means of sufficiently thick metal.
To avoid losing efficiency, four lamp fluorescent fixtures should be at least 24" wide. Six or eight lamp fixtures should be at least 30" wide.
Metal halide lamps produce approximately 110-125 lumens per watt, have a life of approximately 10,000 - 12,000 hours based on 10 hours per start, and have a good color rendition. Light efficiency drops approximately 10% in the first 5,000 hours and another 10% in the second 5,000 hours. Such lamps reach full brightness in about five minutes, but require about 15 minutes to cool down and come to full brightness again after being turned off.
NOTE: More frequent starting and stopping will reduce lamp life.
Lamps must be protected from the ball coming down from the top.
Lamps must be easily changed.
Fixtures and lamps must be easily cleaned. Every fixture should be cleaned at least twice a year.
Daylighting by means of windows in the wall or skylights in the roof is not desirable. Outside lighting is much more intense than indoor lighting, causing an undesirable contrast. Outside lighting varies in intensity, and is, therefore, undependable; it may also cause glare, condensation and maintenance problems.
6.0
Placement of Fixtures
Placing of visible light sources directly over the playing area should be avoided. It is better to keep any visible light sources over or outside of the court alleys.
7.0
Direct or Direct/Indirect Systems
If fluorescent lighting fixtures are placed 16' to 22' over or outside the alleys parallel with the length of the court, they can be tilted inward to give more light to the center of the court and less to the outside. They should be placed parallel to the court surface, not sloped with the roof since this makes the light source more visible and objectionable to the player on the opposite side of the court.
Down-lighting very close to the ceiling generally creates strong contrasts with the darker ceiling, making it difficult for the player to follow a lob.
8.0
Indirect Lighting Systems
Lamps in fixtures aimed at a ceiling that is white bounce the light back to the playing area.
The number of lighting fixtures depends upon the efficiency of the fixture, the height and reflectivity of the ceiling and the level of lighting desired. These fixtures are usually mounted on a pendant and individually hung from the structure. They can also be mounted on a channel parallel to, but outside of, the sidelines. There are also two or three lights per court mounted parallel to and behind the base lines.
These high intensity lights should not be mounted any closer to the roof or structural members than about 6' or a "hot spot" will occur.
Some fixtures will require greater distances, depending upon their light distribution. It is important to note that the ceiling must have a reflective finish.
The open tops of the fixtures must have wire guards on them to prevent balls from falling on the lamps inside the fixtures.
9.0
Wiring
In general, the supply voltage selected should be the highest available. This usually results in 277/480 volt, three phase systems for large facilities, and 120/208 volt, single phase systems for smaller applications. Voltage drop can significantly affect the lumen output of the lamp. Conductors should be sized to limit the voltage drop to 5% or less from the source of the luminaire. All wiring must comply with the National Electrical Code and applicable local electrical and building codes. Consult these codes or a local electrical engineer for wire requirements and wire sizes.
Fluorescent, mercury, and high pressure sodium lighting are stroboscopic (flickering) in nature. This can be eliminated by using three phase wiring, with each alternate fixture on a different phase.
10.0
Control Devices
Many types of control devices are available for tennis court lighting. Centralized switching, remote, or courtside time meters, and coin, token, or ID operated devices are available for different light sources. These options may be investigated for more convenient and efficient control to satisfy project requirements. Switching lights on and off at the counter is desirable.
11.0
Costs
Maintenance, operating, and initial costs should be considered. Initial costs include fixtures, wiring, installation and control equipment. Operating and maintenance costs include electrical operating expenses, lamp and lens replacement, fixture cleaning and labor costs associated therewith.
12.0
Maintenance
All luminaires should be periodically cleaned as recommended by the manufacturer to maintain maximum light output. As much as 30% of the light output can be lost over a period of time if the luminaires are not cleaned on a regular basis. Wipe lenses with a damp cloth since a dry cloth creates static electricity which causes dust to collect more rapidly. Louvres should be dipped in a cleaning solution, then in clear water. Both should be allowed to dry without wiping. Wear gloves when handling lamps since skin oils can reduce their efficiency and life.
Clean the fixtures at the same time relamping takes place. Relamping should occur at 75% of the rated life of the lamp. For economic reasons, it is recommended that all of the fixtures be relamped at the same time, rather than replacing one at a time. Consult luminaire manufacturer for maintenance instructions.
13.0
Special Note
Because of the numerous variables in designing a tennis court lighting system, it is recommended that an owner consult an engineer, architect or qualified tennis consultant or contractor who is completely familiar with tennis court lighting.
Section II.M.2 - Recommended Illumination for Indoor Tennis Facilities
NOTES:
1. Maintained horizontal foot candles is determined by applying a light loss factor (LLF) to the initial calculated or measured foot candles. LLF is dependent upon lamp characteristics, fixture design, fixture maintenance, voltage variations and atmospheric conditions. It normally varies between .6 – .85. Consult the Illuminating Engineering Society Handbook and fixture manufacturer’s publications for proper LLF values.
2. Average maintained and minimum maintained horizontal foot candles should be calculated within the playing lines and/or within the Primary Playing Area (PPA) determined by the specifications of the project with foot candle values multiplied by the appropriate LLF.
3. Uniformity ratio is defined as the ratio of maximum foot candles divided by the minimum foot candles.
4. Primary Playing Area (PPA) is defined as the area that includes 6’ beyond the sidelines and 10’ behind the baseline.
Section II.M.2 - Light Meter Reading Location Diagram
NOTES:
1. Maintained horizontal foot candles is determined by applying a light loss factor (LLF) to the initial calculated or measured foot candles. LLF is dependent upon lamp characteristics, fixture design, fixture maintenance, voltage variations and atmospheric conditions. It normally varies between .6 – .85. Consult the Illuminating Engineering Society Handbook and fixture manufacturer’s publications for proper LLF values.
2. Average maintained and minimum maintained horizontal foot candles should be calculated within the playing lines and/or within the Primary Playing Area (PPA) determined by the specifications of the project with foot candle values multiplied by the appropriate LLF.
3. Uniformity ratio is defined as the ratio of maximum foot candles divided by the minimum foot candles.
4. Primary Playing Area (PPA) is defined as the area that includes 6’ beyond the sidelines and 10’ behind the baseline.
