Led Sports Lighting Retrofits：Table Tennis Court Lighting Retrofit
Directory:
1. Led Sports Lighting Retrofits Introduction
2. Current Status of sport court Lighting and Design Standards
3. Layout plan for choosing traditional lighting fixtures
4. Led Sports Lighting Retrofits Solution
1. Led Sports Lighting Retrofits Introduction
The number of Sports court retrofit projects is on the rise, and nearly every retrofit necessitates modifications to the court's lighting system. The primary aim of these adjustments is often to enhance lighting quality, particularly the illumination standard. Given that factors influencing lamp placement—such as the building's height, structural load, air conditioning equipment, and electrical load capacity—are largely predetermined, relying on traditional metal halide lamps for design and simply increasing the number of lamps may not align with the court's current needs, potentially leading to an unsuccessful retrofit. This article uses the lighting system retrofit of a newly designed table tennis hall as a case study, implementing an LED solution that can serve as a reference for future engineering design projects.
2. Current Status of sport court Lighting and Design Standards
2.1 Current Status of sport court Lighting
This project involves retrofiting a table tennis hall that serves as a daily training facility for the table tennis team. The court consists of three above-ground floors and one underground floor, covering a total area of approximately 13.545m². The second and third floors are dedicated to table tennis training, with ceiling heights of 7.5m and 9.9m, respectively. Each floor contains 24 standard table tennis courts measuring 14m×7m. Currently, the court is equipped with 400W metal halide lamps that provide direct lighting, positioned above the area with light beams directed perpendicularly to the floor. The standard illumination level for the court is set at 800lx horizontally, with four lamps installed in each area. The second-floor lamps are mounted at the same height as the existing sound-absorbing structures, while the third-floor lamps are aligned with the lower chord of the grid, maintaining a minimum clearance of 6m from the ground. The current lamp arrangement is illustrated in Figure 1.
Figure 1
2.2 Requirements for sport court Lighting retrofit
At the request of the sports team, all lighting fixtures in the table tennis courts must be retrofited, raising the illumination standard for regular training from 800lx to 1200lx. Additionally, to enhance athletes' acclimatization to the court prior to competitions, eight courts on each floor will be designated for pre-match training, requiring an illumination level of 1600lx.
2.3 sport court Lighting Design Standards
Based on the principle that the illumination needed by the sports team should align with established standards, the design standard for the sport court lighting retrofit has been defined.
3. Layout for choosing traditional lighting fixtures
The fundamental guideline for lighting design in stadiums is the choice of lamps. Typically, if the lamp installation height is below 6 meters, fluorescent lamps are recommended. For heights between 6 and 18 meters, medium-power metal halide lamps with a maximum power of 400W are preferred. In this retrofit project, the lighting fixtures are installed at a height greater than 6 meters, and the current fixtures are 400W metal halide lamps. To ensure design consistency, this plan will continue to utilize the same type of lamps.
3.1 Lighting solution for regular training
After conducting simulation calculations, the existing lamps will be replaced with high-efficiency 400W metal halide lamps. Additionally, two more lamps will be added to the current arrangement, resulting in a total of six lamps organized in a 2 (rows) × 3 (columns) array. With all six lamps activated, an illumination level of 1200lx can be achieved. The arrangement of the lamps is illustrated in Figure 2.
fig2
3.2 Lighting solution for pre-match adaptive training
The court selected for pre-match adaptive training must also fulfill the requirements for regular training, thus it will be based on the previously mentioned lighting plan for daily training. Following simulation calculations, the lamp arrangement is depicted in the figure below.
During regular training, lamps 1 to 6 will be on while lamps 7 to 10 will remain off. For pre-match adaptive training, lamps 1 to 4 and 7 to 10 will be activated, while lights 5 and 6 will be turned off. This setup allows the normal training lamps to maintain a 2 (rows) × 3 (columns) array, and to achieve the 1600lx illumination standard required for pre-match adaptive training, two additional lamps will be evenly placed based on the normal training lamp positions, forming a 2 (rows) × 4 (columns) array. By reusing lamps 1 to 4. the number of lamps can be minimized while ensuring lighting uniformity, allowing the court to accommodate both regular and pre-match training lighting needs.
3.3 Issues with Conventional Lighting Layouts
The primary challenge with retrofiting sport court lighting using traditional metal halide lamps is the significant increase in the number of lamps required. Each of the 24 courts on a floor must accommodate daily training needs, necessitating two additional lamps per court compared to the original setup. Additionally, for pre-match adaptive training, another eight courts will require four extra lamps each. This results in a total increase of 80 lamps (calculated as 24×2 + 8×4), effectively doubling the original number of lamps (24×4=96), which leads to several complications in the retrofit process.
3.3.1 Glare and Its Effect on Lighting Quality
Given the nature of table tennis, athletes may easily see the court lights when they look up, making glare management crucial. To minimize glare, the angle from the lowest point of the court to the lamp should exceed 45°, with the angle's size influenced by the lamp's installation height and position, with height being the most critical factor. In this project, the installation conditions on the second floor are particularly challenging, as the floor height is 7.7m while the lamps are installed at only 6m, leaving little room for adjustment. Although the retrofit will significantly enhance lighting brightness, these two interconnected factors make the use of anti-glare lamps a viable solution to mitigate glare. However, the existing lamps are equipped with anti-glare transparent ribbed baffles, which athletes have reported as ineffective. The traditional metal halide lamps' anti-glare features struggle to adequately limit glare under the constraints of limited installation conditions and the substantial increase in lamp quantity, which will severely impact lighting quality.
3.3.2 Effects of Lamp Heat on the Air Conditioning System
It is widely recognized that traditional metal halide lamps produce considerable heat. Despite their higher luminous efficiency compared to other light sources, only about 30% of the electrical energy is converted into light, with the actual luminous efficiency potentially dropping below 15% when accounting for losses, meaning the majority of the energy is lost as heat. The significant rise in heat output from the increased number of lamps poses a serious concern for the existing air conditioning system. Adjustments to the specifications or quantity of related equipment, such as air conditioning units, ducts, and vents, will be necessary. However, these modifications are constrained by the current building layout and exceed the feasible limits of this retrofit, rendering the plan impractical.
3.3.3 Effects of Lighting Load on Electrical Systems
1) The total power of the metal halide lamps in this plan ranges from 420W to 440W, which corresponds to the power rating of the electronic ballast. If the number of lamps nearly doubles, it will be necessary to replace the outlet switch and distribution trunk line of the existing low-voltage distribution cabinet for the site lighting circuit.
2) The current site lighting terminal distribution box will need to be replaced, and its terminal lighting branches must be adjusted based on the control method, which will involve adding numerous branch switches and conduits.
3) The existing site lighting control method should be modified to implement an intelligent lighting control system, allowing for switching between pre-match adaptive training, normal training, or cleaning mode by adjusting the on/off levels.
4. Led Sports Lighting Retrofits Solution
4.1 LED Technical Specifications
This design incorporates 36 SMD LEDs in a single package, with a total power consumption of 380W. The lamp features a frosted reflector that ensures symmetrical light distribution.
Based on the LED technical specifications, it is assumed that the installation height of the lamp is 6 meters and the maintenance factor is 0.8. To fulfill the requirements of this retrofit, simulation calculations indicate that the lamp arrangement for normal training mirrors that of the metal halide lamp described in Section 3.1. as illustrated in Figure 2. The lighting setup for pre-match adaptive training is depicted in Figure 3. The horizontal standard of 1600lx is achieved by removing lamps 5 and 6 in Figure 3. while the 1200lx requirement for normal training is met through dimming control.
4.3 Comparison with Traditional Metal Halide Lamp Solutions
This approach reduces the number of lighting fixtures for pre-match adaptive training by 2 compared to the metal halide lamps. Each floor has 8 such courts, resulting in a total reduction of 16 lamps. Specifically, the existing metal halide lamps on the second and third floors will be replaced with LEDs, with 64 LEDs added to each floor to satisfy the transformation requirements. This not only results in a 20% reduction in quantity compared to traditional metal halide lamps but also addresses several issues identified in the metal halide lamp arrangement scheme discussed in Section 3.3.
4.3.1 Glare Management
To minimize glare, the LED lamps used in this project feature frosted reflectors and a diffuse reflection light output mode, effectively reducing the brightness of the lamps. Additionally, the shading angle of the lamps has been tested to ensure compliance with relevant regulations, thereby minimizing glare as much as possible. Prior to the installation of all lamps, select courts were chosen for trial installations. Testing showed that the typical training conditions met standard requirements, although the glare index during pre-match adaptive training was slightly above the standard. However, athletes reported that the glare was acceptable based on their personal experiences.
4.3.2 Lamp Heat Generation
Calculations indicate that the heat produced by LED lights is only 30% or less compared to metal halide lamps. The primary design of the LED lamps in this project includes a molded heat dissipation tube, which facilitates vertical air convection and enhances heat dissipation efficiency. Despite an increase in the number of LEDs compared to traditional lamps, the heat generated is only 60% to 70% of that from existing lamps, which does not significantly affect the air conditioning system.
4.3.3 Electrical System
1) Calculations show that if metal halide lamps are used, the lighting load capacity for each floor will increase by approximately 35kW, necessitating the replacement of the outlet switch and distribution trunk line in the existing low-voltage distribution cabinet for site lighting. In contrast, using LEDs results in a lighting load capacity increase of about 20kW. A review of the original drawings indicates that the frame current of the existing outlet circuit breaker can accommodate the new load, requiring only an adjustment to the switch setting. Furthermore, the original cable design has been retrofited to a higher capacity, meeting current carrying requirements, so there is no need to replace the outlet switches and cables in the low-voltage distribution cabinet for site lighting.
2) The LED system employs a DALI digital dimming control system, with each LED light equipped with its own DALI dimming ballast. This setup is managed by a DALI gateway, enabling functions such as switching, scene setting, dimming, status monitoring, and fault detection. Each DALI dimming ballast has a unique address, allowing for individual control of each lamp, which can cater to the specific needs of each table tennis table or designated area, providing flexible control options. While metal halide lamps can also support individual lamp control, they require a dedicated circuit for each lamp at the terminal distribution box, which would increase the number of outlet switches, pipelines, and intelligent modules, thereby enlarging the distribution box. The DALI control system, however, is unaffected by the number of lamps on a distribution circuit, allowing one circuit to support 3 to 4 LED lights, thus avoiding these complications.
4.3.4 Results of LED sport court Lighting Calculations
The lighting fixtures are configured as outlined in Section 4.2 of this article. During standard training sessions, calculations are conducted for specific courts, particular areas within those courts, and the entire court; during pre-match adaptive training, a specific court is chosen for calculations. The corresponding isoluminance curves for these calculations are illustrated in Figures 4 to 7. This design utilizes LED lighting to meet the required standards for this retrofit project.
Due to the unique challenges of retrofiting gymnasiums, there are often conflicts between the lighting standards and the existing building conditions. When traditional lighting solutions fall short, it is advisable to explore LED options, which can fulfill the requirements while promoting energy efficiency. Currently, there are limited examples of LED being implemented in sports court lighting systems. In new projects and courts that require TV broadcasting, traditional metal halide lamps remain the preferred choice for lighting. However, as LED technology advances and costs decrease, its potential for widespread adoption in these courts will need to be evaluated. This article aims to initiate a discussion on this topic. The opinions and conclusions presented may not be entirely accurate, and I welcome feedback and corrections from colleagues and experts in the field.
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