Moore Street Electricity Substation, City, Sheffield

Summary

Electricity substation. 1968 to designs by consulting architects Jefferson, Sheard and Partners, Sheffield, led by Bryan Jefferson, in association with the Regional Civil Engineers' Department of the CEGB North East Region. Contractors, Longden & Sons Ltd, Sheffield. Reinforced concrete frame with board-marked finish with formwork bolt marks, construction and daywork joints emphasized, concrete floor slabs, blue engineering facing bricks, cladding panels of Cornish granite aggregate.

Description

PLAN: long, rectangular building with angled south-west end. Cable basement, two transformers on ground floor, switchgear on first floor, second floor originally for busbars (now empty), with floors linked by external staircase and covered walkways at east corner, some floors linked by internal staircases. Battery room and ancillary personnel areas at south-west end on ground floor and mezzanine floor, internal staircase and lift.

EXTERIOR: the substation is situated on the north-west side of Moore Street at the junction with Hanover Way. The Moore Street elevation is of seventeen bays of reinforced concrete portal frames mainly located at 21 ft (6.4m) centres along the length of the building. The first two bays are angled, facing onto a roundabout, and on the first floor the tenth, eleventh and twelfth bays project slightly. Between the ground and first floors is a deep, chamfered floor plate, with projecting, rectangular floor beams at the bay divisions. The floor plate between the first and second floors forms a string band with similarly projecting floor beams, with a similar eaves band. Flaring roof coping panels, which are gapped at the projecting roof beams, produce a castellated effect. At ground-floor level the two angled bays and the third, fourth and fifth bays have spaced concrete vertical slats, behind which is glazing. Those to the third to fifth bays have set-back blue brick infill panels beneath. The remainder of the ground floor has set-back blue brick infill between the portal frames, with the exception of bay eleven, which also has vertical concrete slats. Bays eight to sixteen have projecting low, flat-roofed blocks, which are similarly detailed with concrete portal frames, a deep concrete roof and blue brick infill. There are concrete roof ventilators on the slightly lower block in bays eight to ten. The first floor has horizontal aggregate cladding panels fixed over the concrete portal frames with narrow gaps between the panels. The second floor has similarly spaced cladding panels, which are set-back between the portal frames. At the right-hand end is a free-standing external staircase, now enclosed at ground-floor level by a wall of blue bricks. The staircase is triangular with chamfered corners. It has a triangular, board-marked concrete core with a sloping top which projects above the actual staircase. The flights of concrete steps wrap round the core supported on cantilevered brackets. At ground-floor level the staircase walls are infilled with blue brick, at first-floor level narrow vertical concrete slabs are used, while the three upper flights are glazed with narrow vertical panels of glass.

The north-east end elevation is of two bays with a third, narrower bay cantilevered out at first-floor level. Detailing is similar to the Moore Street elevation, with spaced concrete slats with blue brick infill beneath on the ground floor, horizontal cladding panels overlapping the concrete framing on the first floor and set-back on the second floor. At first and second-floor levels are enclosed cantilevered walkways opening off the external staircase at the left-hand end. Both have concrete floor and roof slabs and are glazed with narrow vertical panels of glass.

The south-west end elevation is of a single bay, similarly detailed to the two angled bays which form part of the Moore Street elevation.

The Hodgson Street elevation is of fifteen bays and has similar detailing to the Moore Street elevation, the main difference being that the first floor is cantilevered with large triangular brackets on the portal frames supporting the floor beams. The first floor projects slightly in bays six to eight, mirroring the projecting bays on the Moore Street elevation. The underside of the projecting bays in the Hodgson Street elevation contains a large access hatchway. In bay nine is a projecting semi-circular staircase outshut at ground-floor level, built of blue brick.

INTERIOR: On the ground floor are two large, mirror-image transformer rooms separated by a transverse access way. They have high ceilings, designed so that the brickwork, which is here of orange bricks, can be removed from between the concrete portal frames to enable equipment to be inserted/removed. The transformers are set into large pits. On the outside of each transformer room is a room containing cooling equipment, which is open to the Hodgson Street elevation. Opening off the south-west transformer room is the semi-circular staircase, which connects the ground floor with the cable basement and with a self-contained mezzanine level housing a room with air receiver containers and an air compressor room. Concrete flights of steps rise round a slab-like concrete core, with semi-circular landings. Plastic-coated metal handrails are attached to the inner core. At the south-west end of the building is the ancillary personnel area, with a number of rooms opening off an irregular pentagonal circulation area containing a free-standing concrete staircase. Three flights of concrete steps overhanging a central concrete beam are angled round two intermediate landings to form a triangular shape; the landings are supported on circular concrete columns. The swept balustrades are of metal square-section bars with black plastic-coated handrails. On the north-west side is a personnel lift set in a concrete lift shaft and the other walls in this public area are of blue brick, with small, square blue-glazed tiles on the floors and forming a skirting. The doors opening off both the ground floor and mezzanine landing are of narrow vertical boarding set in a wider stile and rail frame. On the north-east side of the lift is a second concrete staircase with metal balustrades rising from the mezzanine level to the first floor. The flights of steps rise round a slab-like concrete core with intermediate semi-circular landings supported on projecting horizontal beams. The first floor is a single open space with switchgear equipment in fenced-off areas. The access hatchway has a pivoting metal hatch. Attached across the width of the concrete ceiling above are a number of rolled steel girders and winches to facilitate the movement of equipment. There is a large rectangular hatch in the ceiling, now covered, through which the switchgear originally linked with the busbars on the second floor. A doorway in the north-east end wall opens into the covered walkway linking to the external staircase. The second floor is presently empty. At the north-east end is a largely free-standing concrete staircase leading up to the roof. The three flights of concrete steps rise between intermediate landings. The lower landing is supported on a circular concrete column and the upper landing rests against the end wall. The metal balustrades are similar to elsewhere. A doorway in the north-east end wall opens into the upper covered walkway linking to the external staircase. The cable basement has shallow concrete troughs for the cables to run in. In the east corner is an internal staircase leading up to a door opening adjacent to the external staircase.

Pursuant to s.1 (5A) of the Planning (Listed Buildings and Conservation Areas) Act 1990 ('the Act') it is declared that the electrical equipment contained within the substation is not of special architectural or historic interest.

History

During the 1960s electricity distribution in the City of Sheffield called for the use of a 275 kilovolt cable ring around the city centre with transformer and switching substations on the ring to supply the local Area Board 33kilovolt (kV) system. One such substation was required to be sited near the junction of the Moor and Ecclesall Road, an area which in the 1960s was largely occupied by substandard back-to-back housing and numerous small cutlery factories and was in the process of redevelopment. For amenity reasons, and because of the scarcity and high cost of land needed for a conventional open-air substation layout, it was decided to build an enclosed substation containing transformers, switchgear, and busbars on separate floors. The preferred layout would have been square in plan, but provision of a suitable site would have required the closure of several small factories. Consequently, the Sheffield Planning Officer restricted the Central Electricity Generating Board (CEGB) to an L-shaped area occupied by back-to-back properties already scheduled for demolition.

The construction of the substation was due to be carried out in two phases, the first being situated between Moore Street and Hodgson Street and measuring 320 ft (97.5 m) long by 56 ft (17 m) wide, with a corner linking section. Phase 2, forming the other leg of the L, was never built as the increased demand which would have justified its construction did not materialise.

Due to the prominent position, and with extensive redevelopment planned, the architectural treatment of the structure was considered important and the CEGB engaged Jefferson, Sheard and Partners of Sheffield and London as architects to work in collaboration with the Board's own regional civil engineer. The design of both wings was dictated by the structural and statutory requirements of the electrical gear to be housed. Each was to have two 90 MVA transformers on the ground floor, one air-blast switchgear installation on the first floor and associated busbars on the second floor, together with associated ancillary equipment. Factors included weight of the plant and specified air clearance distances which had to be maintained between the structure and live equipment and the necessary clearances for the maintenance of equipment. The statutory clearance laid down by CEGB required an uninterrupted space in the transformer chambers of 99 ft (30 m) by 47 ft 9 in (14.5 m) and this dictated the clear span of the structural framing. A reinforced concrete structural frame was chosen over a steel frame because of the heavy floor loads requiring continuous stress distribution from floor to frame, fireproofing requirements, and the mass required to reduce noise. With no windows needed in the main portions of the structure housing the electrical equipment, the opportunity was taken to design a building which was a powerful expression of its purpose. The building gained considerable critical acclaim and was commended in the Financial Times Industrial Architecture Awards in 1968.

The building remains in use as an electricity substation. The structure has changed very little in appearance other than the building of a short wall at ground-floor level enclosing the base of the external staircase to prevent it being accessible from the street. The inserted wall uses the same type of blue engineering brick as was originally used for the ground floor. Since October 2010 the building has been floodlit with coloured lighting at night-time with the aim of creating a dramatic artistic focal point on the City's ring road (Hanover Way).

Reasons for Listing

The electricity substation, Moore Street, Sheffield, of 1968 by Jefferson, Sheard and Partners, led by Bryan Jefferson, in association with the Regional Civil Engineers' Department of CEGB North East Region, is listed at Grade II for the following principal reasons:
* Planning: built in 1968, this substation is highly unusual for its date as due to its prominent urban position in a post-war redevelopment area the transformers and switchgear are enclosed within an architect-designed building, rather than being located in an open-air site surrounded by security fencing as was the usual form for substations of this period; as such it was commended in the Financial Times Architectural Awards of 1968;
* Architectural Interest: designed in the Brutalist idiom and described as a 'citadel' at the time of its construction, the substation takes the form of a massive and uncompromising bunker which by its plainness and fully-displayed structure expresses a highly appropriate impression of enormous energy confined and controlled within;
* Design: the craftsmanship and attention to detail of the building is clear in the precision of the clean, crisp lines, the scrupulously finished concrete which carries a board-marked finish and formwork bolt marks emphasizing the material's rugged strength, and the placing of the human access in a separate triangular staircase with external walkways, which combine to give the building a dramatic, sculptural quality;
* Interior: the same attention to detail apparent in the exterior is displayed in the ancillary personnel area at the south-west end with the simple forms of the internal free-standing concrete staircase and pentagonal mezzanine landing having a fine sculptural form, as do other internal staircases, while in contrast to the human scale of these elements, are the spaces holding the equipment, which are sublime in their cathedral-like size;
* Historic Interest: the substation forms a significant and highly visible component of a much wider post-war scheme to revitalise Sheffield's infrastructure and bring it to the vanguard of contemporary thinking on urban environments that had commenced under the guidance of City Architect, J L Womersley, and included a number of Brutalist buildings including the Grade II* Park Hill of 1955-61 based on Le Corbusier's Unite de Habitation, Marseilles.

External Links

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