Since the Wimbledon tennis tournament began more than 130 years ago, the game has always been subject to the volatility of English weather and fading light levels. However, from this summer onwards, spectators and TV viewers alike will be able watch the Championship safe in the knowledge that Centre Court’s new retractable roof and lighting system make these threats a thing of the past, thanks to companies such as Lutron, the leading light control provider.
There have been various phases to the refurbishment of the original 1920’s Centre Court and the final phase began in earnest after completion of The Championships back in July 2008. This included the installation of a translucent retractable roof and an extra 1,200 seats, ready for the 2009 Grand Slam event this summer. As would be expected with the refurbishment of a 90 year old building, the lighting scheme installed in the project had to overcome a variety of challenges; these included lighting one of the lowest roof spaces in any professional sports venue worldwide and meeting the high luminance levels required by the BBC for its high-definition coverage of the event. An additional requirement specified by The All England Lawn Tennis Club (AELTC) was to ensure an easy to use, fail-safe way of controlling the lighting for Championship and non-Championship games was installed, whether the roof was open or closed.
Brought in to develop a lighting scheme that would overcome all these challenges was global engineering design company M-E Engineers Ltd. Corey Berhost, associate director at the firm, comments: “In designing the sports lighting for the retractable roof on Wimbledon’s Centre Court we were presented with a unique challenge. Working alongside Ed Ragain, president of M-E Engineers, who was responsible for the conceptual design, my job was to bring the project to actualisation. The sliding roof was to be far lower than any other major professional venue in the world, creating a potential problem with glare to the players. Working with the architects, Populous, and the client we introduced the technique of indirect sports lighting. What was discovered was that by reflecting some of the light off the roof itself, we could add a layer of diffuse light to blanket the court and this reduced the need for the quantity of glare producing direct luminaires. The indirect light also has another effect; by increasing the luminance of the roof, it makes the lights aimed directly at the court appear visually less glary. In order for this approach to come to fruition an influence into the entire architecture of the bowl needed to be part of our analysis. Everything from the selection of a fabric roof membrane to the colour selection of the moving roof trusses played a major role in the symbiosis of the system integration.”
This is the first time that indirect lighting has been used to light such a renowned sports arena and the innovative scheme at Centre Court combines 48 direct with 72 indirect luminaires. Sixty of the indirect luminaires are fitted to the retractable trusses and focused onto the reflective roof fabric, creating a blanket of overlay light. Shielding and aiming techniques were then employed to ensure that the direct lights met M-E Engineers best-practice thresholds for glare in a sports arena. To ensure that the theory worked in practice, Berhost and his team divided the court into one metre squares and manually checked for glare from every direction.
Ultimate control
Not only did Berhost and his team have to consider the experience for visitors, viewers and players, but they also had to ensure that the lighting scheme could be controlled with ultimate precision. To achieve the levels of light control required, Lutron’s GRAFIK™ 7000, stadium light control solution was installed. Scalable to manage a project of any size or complexity, Lutron’s GRAFIK 7000 control system provides the ultimate centralised lighting control solution. With multiple processor capacity (up to 32 processors) of 16,384 zones and 6,144 Control Station Devices, the system is well placed to cope with stadia of any capacity. At Wimbledon Centre Court, three GRAFIK 7000 processors have been used and 24 Lutron XP Softswitch™ power and switching panels, alongside a Graphical User Interface in the master control room, to ensure ultimate control of all the lighting circuits.
The system has been programmed to have two operating modes – Championship and non-Championship. When the system is in non-Championship mode, the lighting levels can be altered to suit specific requirements, however, once switched to Championship mode there is no room for user error, as everything is pre-programmed and fully automated. Even in non-Championship mode however, there are preset scenes in place to ensure that as soon as the sports lighting is turned on, the bowl lighting around the stadium is turned off, ensuring players have minimum distractions.
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Not only is the players’, visitors’ and viewers’ visual comfort pre-programmed into every lighting scene, health and safety considerations are integral to the system as well. The GRAFIK 7000 processors have been integrated into the retractable roof signalling system, so that on requiring the roof to open or close, a chain of lighting sequences are put in place for optimum visual comfort and safety. When closing, the lighting sequences are not activated until the roof locking pins go into place and subsequently, when the roof is ready to be retracted the sports lights are automatically turned off and allowed a ten minute cool-down period before the trusses begin to open and manual control of the scenes is regained again.
Lights, cameras, action!
With the indirect and direct luminaires achieving required luminance levels for both the players and the crowd in Championship and non-Championship modes, the requirements of the TV companies also had to be satisfied. On installation of the scheme sports lighting testing was carried out on Centre Court with the BBC. The testing was to evaluate the requirements of high definition television cameras with respect to colour rendering and colour temperature variation using various lamping configurations. The design passed with flying colours and the scheme was praised by the BBC team for its innovative use of materials to bring “elements of theatricality, drama and sophistication” to the overall design.
So, with the Wimbledon Centre Court’s capacity increased to 15,000, the installation of new, wider seats and the retractable roof and lighting system, the 2009 Championships look set to be the biggest and best ever.
The retractable roof
• The retractable roof is divided into two sections with a total of 10 bays of structural fabric — 5 bays in one section and five in the other. Each of the 10 bays of structural fabric is clamped on either side by prismatic steel trusses. There are 10 trusses spanning approximately 77 metres across the court. The ends of each truss are supported by a set of wheels that move along a track positioned on the new ‘fixed’ roof of the Centre Court.
• A key element of the design has been to allow natural light to reach the grass, while an airflow system will remove condensation from within the bowl to provide the optimum internal environment for the grass court when the roof is closed.
• The arch shape to the tops of the trusses helps the structure to withstand loading from elements such as snow and wind when the roof is stretched and closed over the court.
