DW Windsor provided a total restoration of the light fittings, including the upgrade to more efficient electronically controlled 210W CDM Elite lamps. Although LEDs were considered, the number needed to give the required performance could not be accommodated in the existing lanterns. When the technology becomes available, the lamps will be dimmed from 60% to 40% between midnight and 6am, to give additional savings.
A particularly important consideration was to give adequate light for pedestrians and drivers while preventing passing ships from being distracted by light from the bridge. To control backward light spill into the Thames, a special white glazing panel was used on the sections of the lanterns directly facing the river. Distribution of light was further controlled using DW Windsor’s patented reflector system. The Diamond Optic® comprises four multi-faceted internal reflectors arranged in the shape of a diamond, which can be independently adjusted to control the light distribution from each lantern.
The bridge had to remain open for the whole restoration period, so lanterns were removed in phases. Because of the harsh nature of the environment, the lanterns were repainted using the latest paint technology, PSX (an extremely resilient material for marine environments), further minimising disruption to the use of the bridge due to maintenance.
The scheme now attracts a 26% energy saving, representing 7,788 kw/h per year.