Kings Cross Station Train Sheds
With the use of 3D solid modelling and careful design, Holophane has enabled a projected 56% energy reduction in lighting energy consumption, compared to the original design for this lighting upgrade for two train sheds at Kings Cross station.
The energy savings have been achieved through a combination of high efficiency optimally-positioned luminaires, enabling smaller lamps to be used to achieve the required illuminance levels, combined with advanced lighting control through the HOLOS 2 system.
The current Kings Cross station was designed by architect Lewis Cubitt and opened in 1852. It is the earliest of the great London stations to be still intact and has Grade I listed status. It was therefore important that the Holophane solution was sympathetic to the building's architecture as well as the lighting requirements.
Another of the key criteria for the lighting upgrade was to ensure that a minimum illuminance of 150 lux was achieved at platform level with rolling stock present in all track beds. The initial design for the lighting in these barrel-roof train sheds called for installation of 160 x 450W Holophane Prismpack luminaires (80 in each shed), using the original mounting points.
However, Holophane's design team carried out 3D modelling of the space and identified that the original mounting positions – in two rows of 40 in each shed – were not optimised relative to the platforms.
It was also identified that re-positioning of the luminaires in four rows of 20 per shed, making full use of Prismpack's even light distribution, would enable the same illuminance levels to be achieved using 320W lamps.
In the event, the client was uncomfortable that 320W lamps were only available from one supplier, so opted for more widely available 400W lamps. This has resulted in a reduction in installed electrical load of around 9% when control gear losses are taken into account.
Using Holophane's Optimised Lighting Operating System (HOLOS 2), which enables the lamps to be dimmed, the 400W lamps have been set to under-run initially to reduce energy consumption while delivering the required light output. As the lamps age and lumen output falls, the illuminance levels will be maintained by increasing power to them.
Once commissioned, the ability conferred by the HOLOS 2 system to dim the metal halide lighting will also enables the lighting to be dimmed in relation to daylight entering the roof lights, so that the power consumption of the luminaires can be reduced whenever daylight levels allow.
In addition, the HOLOS 2 system will dim the lighting to deliver illuminance levels of 50 lux between the hours of midnight and 4am, thus reducing energy consumption even further.
Overall, when compared to the initial design using 450W lamps with no control, the Holophane solution will deliver energy savings of around 56%, with a projected financial saving on running costs (including maintenance) of £28,412 per annum.
Many lighting retrofit projects simply replace like-for-like as the easiest option, taking little or no account of advances in lighting technology since the original installation. This project clearly illustrates the benefits of 'revisiting' such designs and making maximum use of the products that are currently available.
In this case, those benefits equate to significantly lower cost of ownership for the client, with a reduction in carbon emissions through improved energy efficiency.
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July 2011
