Case study: Bank of England

The Bank moved into its purpose built premises in Threadneedle Street, London in 1734 and over the years the site has been remodelled by a distinguished line of architects. These include Sir John Soane who was responsible for extending the Banks site and eventually enclosing it in 1828 and Sir Herbert Baker who was responsible for demolishing the original premises and building a new much taller head quarters for the Bank which was completed in 1939. Following the success of architects Sheppard Robson’s initial scheme for the Bank of England in 1997 they were appointed to design the refurbishment of the famous Banking Halls in 2001. The broad proposal was to replace the 1970s prismatic bi-directional fluorescent perimeter lighting with central pendants.The ChallengesThe challenge was to light from fixed positions and to required levels and uniformity a vast space in a way sympathetic to the restoration architecture and to design luminaires which would be maintenance friendly. Furthermore there was a need for discreet emergency lighting.

The SolutionsETAP was awarded the contract to design, engineer and manufacture the specialist lighting. An innovative pendant complemented the sympathetic restoration. It was engineered to uplight the vaulted ceilings whilst providing a diffused yet effective downward component, this equated to each luminaire having a total package of 75,000 lumens. The vast size of the pendants, some two metres in diameter and the five metre mounting height posed a difficult maintenance challenge. To overcome this a unique solution was incorporated into the design which allowed the fittings to be revolved to give access from one location. The individual lamp and gear tray could then be removed and maintenance carried out at ground level. For the uplighting, a concept was devised which would be unobtrusive, have low glare and incorporate spotlights to highlight the architectural features. This was achieved by inverting ETAP’s highly efficient T5 Thalia® optic, upgrading the lamps to high output T5 and integrating it into the top of the desk partitions. To provide accent lighting narrow beam 70W CDM-TC spotlights with electronic metal halide control gear were inset between the fluorescent fixtures.

Emergency lighting was required that had to suit the interior without affecting the building fabric. It was essential that it could be incorporated not only into the pendants but also the uplights. The solution for the pendants was to utilise the downward element within the luminaires to provide anti panic emergency lighting, whilst the uplights had additional reflectors incorporated to redirect light downwards through decorative slots in the side of the desk partitions. Due to the complex geometry of the Banking Halls changes to the interior design were ongoing requiring recalculations of the lighting levels and ETAP made use of a sophisticated 3D system to predict the lighting levels which were born out in the end result achieving the lighting levels specified by the design team. The completion and the overall effect of this prestigious project has proved that such interiors as the Bank of England can embrace today’s technology without compromise to its original design.