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London Velodrome, Olympic Park, London, UK

Issue 68 Aug / Sep 2012 : Architecture : Stadium

LIGHTING DESIGN: BDSP ARCHITECT: Hopkins Architects


One of the few venues in the Olympic Park that will remain unchanged in legacy mode, the London Velodrome is designed to accommodate different uses from everyday training through to HD broadcasting.

Pic: London 2012 / ODA / David Poultney

Hopkins Architects’ Velodrome was one of the first Olympic Park venues to be completed back in January 2011. Drawing inspiration from the ergonomic beauty and efficiency of a modern racing bike, the design features a distinctive hyperbolic paraboloid roof and cedar-clad upper bowl structure that echo the racing track inside. A public concourse runs around the venue, separating the upper and lower seating tiers – visible from the outside as a glazed band that wraps around the venue’s base.
Hopkins Architects worked with BDSP who carried out the internal and external lighting designs and set out the track lighting criteria based on CIBSE recommendations, HDTV requirements and experience gained from previous Olympic Velodromes.

BDSP in turn appointed a specialist lighting manufacturer to carry out the design and implementation of a track lighting system that would meet the needs of both ‘games time’ and ‘legacy mode’ use, as well as fitting elegantly within the structure.

The team established a series of objectives for the lighting scheme:
• To use arena lighting for access, security and to provide secondary lighting should a power failure occur during an event or training.
• To provide an uninterruptable power supply to maintain a minimum of 50% of the lighting output on power failure or ‘brown out; for cycling safety and to allow events to continue.
• To provide appropriate lighting levels for different modes of use, including training, elite training, events and broadcast events.
• To provide sufficient glare- and shadow-free daylight to allow training without the need for artificial lighting for significant. parts of the year (during daylight hours).
• To allocate groups of lighting that will be used in alternation to ensure running hours for lamps are evened out.
• To develop a containment and support system that integrates with the roof design to allow for wind movement and avoid excessive ‘clutter’.
• To locate fitments in a way that will increase ease of maintenance.

The team developed a solution that uses 1000W double-ended, 90,000 lumen discharge lamps with Ra 90 and Tc 5600 to cover the track and infield areas. The floodlight enclosures have highly efficient optics, precision aiming and separate control gear housings. A common lamp size and type is used throughout and the optical control uses various optics within a common lamp housing, thus reducing the need for multiple spares.

The Velodrome roof is constructed using a floating cable net system. Skylight strips run the length of the main hall, so a combined containment and hanging system was developed to sit between them. Attached using the roof cable-net nodes as connection points, the containment systems are articulated so that they can follow the curve of the ceiling. This articulation also allows for movement of the roof in high winds or under heavy snow cover.

Each run of lighting was constructed at ground level where wiring could be temporarily connected to undergo final testing for faults. Fittings were all pre-aimed in accordance with the lighting design, then the whole lighting system was lifted into place using motorised hoists of the kind used in stage lighting. Once locked into position, the cable ends were extended and teminated and the system re-tested. Horizontal and vertical illumination levels were checked against those in the design predictions, making allowance for the increased output for new lamps in clean fittings. All subsequent checks had to be carried out at night with all other site lighting isolated – a process that had to be repeated for each of the different lighting modes (training, elite training, event and broadcast event).

The containment system allows the mounting of floodlights on a pre-arranged grid to enable future changes to be accommodated.
The cable net system is designed to support abseilers, should this be necessary prior to a critical televised event, though replacement of lamps or failed units would normally be carried out using a mobile platform, from which all but a few fixtures will be accessible. To help speed replacement the control gear housing and fittings have ‘plug & play’ connections for speedy isolation and quick release physical connections for complete removal. For final removal or replacement a lanyard system provides extra safety.

In Broadcast mode, when HDTV conditions are required, the arena track and infield lighting load is approximately 360kW. Broadcast lighting is designed to provide 2000 lux with good overall uniformity including vertical uniformity for key camera positions. The illumination level follows the requirements from the Broadcast Authorities for both normal HDTV and slow motion playback.

Extensive lighting simulation studies were carried out using the lighting suppliers’ software and expertise. These were checked and verified in house using a ray tracing software package.

Should the event suffer a power failure, or momentary power fluctuation (‘brown out’), the system will maintain 50% of the lighting for 15 minutes, with a further 30 minutes at 25%. This provides cyclist safety and potentially allows the current track event to be completed. At the end of the supported times, if power has not returned, lamps will be sequentially turned off with a selection maintained for three hours to aid an organised evacuation of the building.

Provision is included for additional temporary support of the remaining 50% during Games use.

Non televised event lighting is designed to deliver 1000 lux, again with 50% of the lighting maintained during a power failure or ‘brown out’.
Other lighting modes provide 750 lux for elite training and 300 lux for normal training.

Major televised events are envisaged to take place in the Velodrome, but these are expected to represent less than 10% of the hours of operation of the venue according to their business plan. Whilst high lighting levels will be required when these events occur, for the rest of the time (90%), lighting levels can be maintained at much lower levels. During normal day-to-day operation, when only 300 lux are required for general training, daylight from the rooflights will offset much of the lighting energy required, resulting in substantial energy savings.
A computer simulated daylighting study was undertaken in order to select the optimum rooflight glass type, size and location. This allows maximum use of the arena during daylight hours without using the arena and infield artificial lighting for a significant proportion of anticipated daytime use. The rooflights use diffusing glass with two PVB interlayers to prevent hard shadows that might distract cyclists on the track.

When the track is used in normal ‘training mode’, a photo cell will advise the user if there is sufficient daylight available for training without artificial lighting. The user can still turn on the artificial lighting system at any time during the training period. The lighting sensor is advisory only for the track and infield, so automated switch off with rising daylight does not take place. This safeguards the cyclists as discharge lamps need a cooling down period before they can be re-ignited.
All the lighting for other areas of the building uses either compact fluorescent or fluorescent lamps sources. The lighting design by BDSP had been carried out in co-ordination with the architect’s requirements to supplement the building architecture and provide a simple, minimalist lighting design that is functional and integrates with the architectural vision.

Linear fluorescent surface mounted luminaires are generally used in the non-public areas with recessed compact fluorescent downlights used in the concourse and public circulation areas.

The external lighting of the concourse is provided via discrete bespoke luminaires integrated within the handrails, which also serve to provide emergency illumination.

The lighting is generally controlled via absence or presence detection, together with a central lighting control system that can override the detectors if the public area lighting needs to be kept on for events.
The building public areas and the main arena are designed to allow admittance of daylight. At concourse level, vertical glazing allows daylight and a visual connection both inside and out. Back of house spaces with daylight includes daylight linking to the artificial lighting. All enclosed spaces include absence or presence detection.

As much as possible, daylighting is utilised throughout the building, helping to contribute to its energy efficiency – particularly in the post-games role.

PROJECT DETAILS
London Velodrome, Olympic Park, London, UK
Client: Olympic Delivery Authority
Architect: Hopkins Architects
Engineers: expedition Engineering
Lighting Design: BDSP

 

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