Most of the lighting for this area comprised 4.25m columns fitted with the now iconic spherical post-top globe lantern. Another idea ahead of its time was to use “white light” for the city centre pedestrian areas. However, at that time (1970s and 80s), white light sources only delivered about 50 lumens/watt and they were later replaced by more energy saving 70W and 100W high pressure sodium lamps, albeit the light was “gold” in colour.
ChallengeIn 2016, Milton Keynes Council and Ringway, the contractors for the project, identified that the older lanterns were coming to the end of their useful life and developed a plan for their replacement.
They then approached the designers at Holophane and their challenge was how to deliver a modern, ultra-efficient lantern which still retained the iconic style of the original units.
The new lantern should also be future-proof in terms of controls and programming. It also had to be easily retrofitted on to the existing columns. As such, the new lantern had to have a choice of optical distribution so that it could equal or improve the existing lighting.
SolutionThe CityMax is an award winning lantern (Lux Awards 2017) offering a range of light output, from 2,000 – 15,000 lumens and four different optical distributions. The lantern, itself, is shallow in depth and circular in plan.
In order to adapt the lantern to make it more similar to the original Milton Keynes concept, the Holophane engineers, in conjunction with MK Highways and Ringway, developed a specially curved mounting bracket so that in outline, it retains the shape of the original globes. The design of the new bracket is visually “lighter” than the globes and intrudes less on the view of the wide open skies over CMK. The bracket design also means it has reduced windage which is a useful feature when retrofitting on to older columns.
Although the globe lanterns are predominantly used in Central Milton Keynes, there are other areas such as the train station and some residential areas where they are also used. It is hoped that this new design can be extended to other parts of the city. As such, the bracket is now a standard option in the CityMax range.
In terms of energy, the new design saves over 30W per lantern which means up to a 50% saving over the existing scheme whilst delivering a quality white light. Furthermore, the current lanterns are programmed to dim to 70% between 10pm and 6am. Further energy savings will be made by fitting 7-pin NEMA sockets. This allows for smart control of the lanterns and light output by having an extra two or four control circuits such as CMS or DALI.
Maintenance costs are also greatly reduced. The high-pressure sodium lamps typically had to be replaced every three years. The new LEDs in the CityMax lanterns have a rated life of 100,000 hours (L70B50@25C).
Download the Case Study PDF here.