One Knightsbridge Green, a 1950s combination of high street shops and offices, has had new life breathed into it by architect Hurley, Robertson and Associates, with fit-out by DEGW The sense of London's Knightsbridge area around Harrods is of retail streets rather than an office quarter. And that sense has been reinforced by Hurley, Robertson and Associates' (HRA) reworking of 1 Knightsbridge Green, though the building is both retail podium and office block. The recessive offices retain their original, low-profile 1950s fenestration, a decision that suited both the planner and the architect. The brickwork and reconstructed stone were simply cleaned. However, for the podium fronting onto Brompton Road, former single-storey retail units with an office floor above have been remodelled into two-storey retail units, incorporating mezzanine floors.
The elegantly glazed shopfronts (see Working Detail, pages 32 and 33) are on a scale that suits the townscape here, while their uniform rhythm conceals the potential to group them into retail units of different widths. The faceted glazing of each shopfront unit is framed in terracotta rainscreen tiles, linking the frontages beneath the railings and yew hedge of the roof terrace. There are local references here - the orange masonry of Harrods and other nearby buildings, and the articulated shopfronts echoing arcade facades such as those in Burlington Arcade.
Turning the corner away from Brompton Road to the calmer Knightsbridge Green, the shopfronts give way to two-storey structural glazing. In many small-town locations, that language would clearly suggest 'prestige office'. Here it reads less demonstratively - the glazing could be another retail unit, a cafe, a theatre entrance - an ambiguity encouraged by the use of lemon yellow painted plaster immediately inside the glazing. Only when you look further in from the storm of the traffic to the calm within is prestige office the evident use.
While the retail reworking was a clear need, the office entrance was a less clear-cut opportunity. The former two-storey lobby was cramped, with the lifts immediately inside the entrance facing each other 2.5m apart, creating a bottleneck at busy times. A smart move by HRA has been to hollow out of the structure a much larger entrance hall beyond the lifts, and to draw people in to a reception desk at its heart, past the ground floor lifts as if they did not exist. What you notice is the blue glass walls. Once at this reception point, set on a limestone floor with beech-clad walls, escalators then take you to the first floor, where you can take a lift more easily or enter the office area at this level. With only that simple job to do, the first floor entrance space feels a little large and undefined, but it is a necessary part of the whole, now more-spacious, reworking.
Another 1950s legacy is a pair of columns immediately beyond the lifts, also making entry to the new entrance hall feel restricted.
The building was propped and these columns removed for its full height, replaced by steel columns farther apart. The steps in the entrance hall are a legacy of original changes of level.
HRA's other main contribution, working with the engineer, has been to provide a serviced shell for offices. Typically for a 1950s building, floor-to-ceiling height was very restricted. On the office floors, 70mm of screed was removed and a new 100mm raised floor with 70mm working height has been installed. At ceiling level, the air conditioning that the client required is provided using chilled beams and ceiling panels in a 250mm zone. The remaining clear height is 2,445mm, not generous, although it does not feel oppressive, with light colours and floor plates generally no more than 14.75m deep, and daylight from both sides.
With HRA having set this framework, it was architect DEGW's turn to fit out the offices on floors 1-5 for J Walter Thompson (JWT), the advertising/communications group. JWT's move from previous premises was wrapped up with a redefining of JWT as a brand in the communications marketplace.Various in-house groups had come up with descriptions of today's organisation as 'wholesome, not too glamorous, very efficient, best of British, fun'. Ideas for the JWT culture of tomorrow focused on 'risk, teamwork, together, well run, complex, standing out from the crowd, new beginnings'. The same exercises rated the previous building:
on the good side, 'enclosed space (mostly cellular), natural light/aspect, located with team', and on the bad side, 'run down/depressing, temperature control, poor ventilation, cramped, no plan in layout'. So the fit-out was heavy with expectations, as well as the usual anxieties about change.
The JWT letting begins in the first floor entrance hall, where the office entrance has been offset to one side of the back wall to avoid the centreline row of '50s V-shaped columns. You enter a large, open area with 'doughnut' reception desk under a rooflight, knowledge centre shelving (a symbol of a knowledge-based organisation) and seating for meeting visitors. To the left, beyond the row of V-shaped columns, are audio-visual areas for previewing adverts and the like. A cow looks on.
There is a new, open helical stair leading up to the second floor. This connection helps create a two-storey heart to the letting, and lessens the sense that there are five separate floors only otherwise reached by lift from the public lobby. On the second floor, there are work areas and meeting spaces, as well as a communal cafe and access to the roof terrace seating, which is exclusive to JWT.
In the office spaces, typically, the central spine as you enter is for a mix of small accounts, while the side areas are used by teams on larger projects. There are also meeting areas, but space-demand is not currently high enough to necessitate touchdown desks. The 'creatives' are split through the team areas, rather than being grouped together.
The interior open plan is drawn together by the use of furniture and white decor with occasional stripes of colour, and the shallowness of the indented plan. (Floors seven to 10 are just the central rectangle. ) The space feels fairly ordered and tidy, although it is perhaps early days for a more occupied (ie messy) feel. It works as workspace. It is, though, 'engine-room' design, with little attempt to carry through the symbols of corporate culture-change evident in the client-facing spaces on the lowest two floors, which some staff may never see day-to-day. JWT relies on the persuasiveness of audio-visual media for its livelihood.
Perhaps there could have been more faith in the persuasiveness of the medium of architecture to communicate the new JWT among staff.
As to the building overall, it has a good-to-work-in feel. It is a significant transformation of an unpromising building that others might have written off as ready for demolition. There was not, after all, a lot of 'character' to build on.
HRA has succeeded in making this refurbishment a rejuvenation.
Architect's account On the face of it, One Knightsbridge Green looked to be an uninspiring prospect for refurbishment.
The original building was completed in 1956 as a naturally ventilated rent-slab office block designed by Stone Toms & Partners for Edger Investments and built by Sir Robert McAlpine. The building, now owned by Prudential, was occupied until 1989 and then lay empty for 10 years while a series of masterplan initiatives were prepared to redevelop the entire site. By 1998, the concept of a strategic masterplan had fallen by the wayside and Hurley, Robertson and Associates (HRA) was appointed by Prudential to prepare ideas for its autonomous refurbishment.
The challenge was to create opportunities to revitalise the building and the surrounding areas and to find solutions to deal with the various deficiencies of a largely obsolete building.
In strategic terms, our design approach was to focus attention on the design of the retail podium base and leave the external appearance of the office building largely untouched.This approach coincided with Westminster Planners' thinking; they supported our ideas for the regeneration of the building but resisted any proposals to re-clad and accentuate the dominance of the existing 1950s office block.
Our designs for the retail units completely altered the character and configuration of the existing podium base, contextually linking the building with the colour and texture of surrounding brick and terracotta, which are characteristic of this part of Knightsbridge and in close proximity to Harrods.
Triga, a sculpture by Franta Belsky, has been preserved, refurbished and illuminated and is an interesting corner piece on the chamfered facade overlooking Knightsbridge Green.The commitment to public art has extended to a new brick sculpture by Richard Kindersley on the Raphael Street underpass, where 'The Innocence of Childhood'graphically depicts the 'hurleyburley'of street life and provides a moment of reflection for passers-by.The sculpture portrays a child's view of shopping - an appropriate theme in busy Brompton Road.
The opportunity to redevelop the One Knightsbridge Green site may have been lost for a generation, but the 1950s building has been given a new lease of life and an important part of London has been regenerated by a series of ideas and alterations that enhance the streetscape and users'enjoyment of the new spaces in and around the building.
Nick Bullen, Roger Preston and Partners
The building is a child of the 1950s and was originally operated as a heated-only building with operable windows at all floor levels to provide ventilation and cooling.The constraints of the existing structure only provide a clear zone of 2,800 mm between slabs at each floor level and had very little existing plant area.
The strategy proposed by consulting engineer Roger Preston and Partners for controlling the internal environment uses a combination of chilled ceilings and active chilled beams together with a new perimeter heating installation. This technology is recognised as providing good comfort levels and is inherently energy efficient. It also has the major advantage of requiring only a 250mm ceiling and services zone. Together with a 100mm raised floor to distribute data and power this allowed a clear finished floor to ceiling height of 2,445mm to be achieved.
Other solutions investigated either significantly reduced net floor area or required lower ceiling heights.
The planning grid is aligned with the window mullions and allows the formation of cellular space without the need to alter pipe or ductwork arrangements. Additional cooling can be provided in a particular zone simply by replacing a chilled ceiling panel with an active chilled beam.
Restrictions imposed by the planners meant we could only locate low-level heat rejection plant on the open roof. Partial use of the underground car park allowed the chilled water and air handling plant, together with water storage and the stand-by generators, to be housed within the basement, while heating boilers and pumps were installed within the existing oversized lift motor room enclosure.
The building has only four passenger lift shafts. However, with the use of escalators to link the new reception to the first floor lift lobby and modern lift controls, we were able to achieve current lift performance standards without the high cost of increasing shaft numbers.
The building falls within the requirements of Section 20 of the London Building Acts. Roger Preston Fire developed a fire strategy for the building which upgraded lifts at both ends of the building for fire-fighting purposes but essentially retained the original features of natural ventilation to fire-fighting lobbies, and sprinkler protection to basement and retail areas.
The electrical supply to the building has been upgraded within the existing substations and serves the office floors via bus duct risers with tap off units at each floor level. Standby generation is provided for life safety systems with space allocated to allow incoming tenants to increase this to 100 per cent back-up.
John Towers, Waterman Partnership
The project team concept was to minimise the modifications to the existing structure as part of a risk management strategy. Areas of the building where modifications were essential were opened up and investigated in advance.
For the new roof-level plantroom along the length of the building, extensive review and assessment of existing drawings was undertaken to determine which elements needed to be strengthened.
Existing screeds were removed from all floors, providing a load reduction which helped balance the extra load from the new plantroom and helped increase available office headroom.
Generally, the building modifications involved the cutting of openings and installation of trimming steels. Extensive cutting back of the Brompton Road facade was required for installation of the double-storey terracotta and glass facades. The roof over the retail area was removed and replaced with a steel-framed composite deck to cater for its occupation, with appropriate allowances for superimposed loads and heavy finishes, including a grass lawn.
There were major strengthening elements to the project. Between the entrance hall and office floors, two existing columns formed a visual constriction. The 13-storey high columns supporting the central spine strip were moved by approximately half a metre each. Waterman Partnership installed temporary propping, placed new steel columns and jacked back the loadings from the surrounding superstructure in careful sequence. Differential shortening of columns was particularly significant, as was the magnitude and timing of the jacking process.
This project shows that a successful project can be delivered by engineers and architects working together well in an open and responsive project culture, supported by an enthusiastic client.
Costs based on final account rounded up or down
SUBSTRUCTURE 2Piling to retail units only (minimal works required)
SUPERSTRUCTURE FRAME/UPPER FLOORS/STAIRCASES £96.34/m 2Concrete and steel works to retail units, modifications and alterations to existing building including stairs and modifications to form holes for escalators
ROOF/ROOFLIGHTS £41.70 /m 2Removal of existing screed, new screed.Upstands, flashings, etc, to flat membrane roof
EXTERNAL WALLS £136.48/m 2Clean existing facade, new louvres, new retail facade/shopfronts and glazing, new office entrance
WINDOWS/ EXTERNAL DOORS £58.55 /m 2Replacement windows to offices
INTERNAL WALLS AND PARTITIONS £90.12/m 2Blockwork and drylining to offices and retail units INTERNAL DOORS £18.61/m 2New doors and ironmongery
INTERNAL FINISHES WALL FINISHES £64.30/m 2Timber veneer, stone and drylined walls to entrance hall and cores.Drylining, timber veneer and tiling to WCs.Paint to back of house areas and shell offices
FLOOR FINISHES £52.62/m 2Raised floor and carpet to offices, terrazzo and limestone to lobbies, entrance hall and WCs; carpet and vinyl elsewhere
CEILING FINISHES £22.04/m 2Plasterboard ceiling to cores and entrance hall
FITTINGS AND FURNISHINGS 2Reception desks, other ancillary fixtures and fittings
SERVICES 2APPLIANCES/DISPOSAL AND WATER INSTALLATIONS Mechanical plant, disposal, services equipment, water installations, boilers, etc
SPACE HEATING/AIR TREATMENT £64.93/m 2Chilled beam ceiling installation
ELECTRICAL SERVICES £87.80/m 2
LIFT AND CONVEYOR INSTALLATIONS £58.06/m 2Two goods lifts, six passenger lifts and two escalators
PROTECTIVE INSTALLATIONS £9.87/m 2Security installations
COMMUNICATION INSTALLATIONS £34.32/m 2BMS installations
BUILDERS'WORK IN CONNECTION £69.57/m 2Builders'work, firestopping, metalwork items and security shutters
EXTERNAL WORKS 2Granite planters to roof terrace and ground floor, soft landscaping and hard pavings
PRELIMINARIES AND INSURANCES PRELIMINARIES, OVERHEADS £161.54/m 2
AND PROFIT Contractor preliminaries, pre-commencement costs, operation and maintenance manuals
CREDITS DATE TENDER DATE First quarter 2000 START ON SITE DATE 2 March 2000
CONTRACT DURATION 19 months
GROSS EXTERNAL FLOOR AREA 25,251m 2
FORM OF PROCUREMENT Contract - JCT 98 Private with Quantities with Sectional Completion and Contractor Designed Portion Supplements.
Procurement by twostage lump sum
TOTAL COST £31,850,000 Astec; raised floors Hewetson; roof finishes Coverite; masonry facade cleaning PAYE; toilets, kitchen and lobby fit-out Swift Horsman; entrance hall fit-out, general joinery and signage Ruddy Joinery; ironmongery Allgood; security shutters Amber Doors; security installation Tyco ( TWG White Group); fire protection R+S Fire Security; landscaping Tilbrooks Landscape; pavement lights Luxcrete; paving stone Blanc de Bierges
QUANTITY SURVEYOR Gardiner & Theobald
SERVICES ENGINEER Roger Preston & Partners
IT CONSULTANT Moffat Communications
STRUCTURAL ENGINEER Waterman Partnership
SUBCONTRACTORS AND SUPPLIERS Specialist and general joinery Swift Horsman; partitions R&S Dri Wall; staircase and roof terrace link bridge CMF; ceilings Astec Projects;mechanical Meica Services; electrical Gratte Brothers; flooring Rees Flooring; decorations David Hartrup; audiovisual consultant DDI; signageModulex; catering project management
KARM Projects; kitchen design IFSE; sliding-folding wall HuppeForm; cabling Communica; security White Group Electronics
REFURBISHMENT CLIENT Prudential Property Investment Managers
ARCHITECT Hurley, Robertson and Associates: John Robertson, Bill Wallin, Ken McLaughlin, Alan RafterPhillips, Kai Fabiunke, Ric Gandolfi, Chris Axon, Scot Donnell, Bob Cox, Max Skjöldebrand
QUANTITY SURVEYOR Gardiner & Theobald
STRUCTURAL ENGINEER Waterman Partnership: John Towers, Barry Dobbins, Julian Traxer
SERVICES ENGINEER Roger Preston & Partners
MAIN CONTRACTOR Bovis Lend Lease
LANDSCAPE CONSULTANT Randle Siddeley
CLADDING CONSULTANT Arup Facade Engineering
FURNITURE COORDINATION Dovetail Furniture Consultants
SUBCONTRACTORS AND SUPPLIERS Piling Fondedile Foundations; steelwork Byrne Brothers (Formwork); mechanical Meica Services; electrical Gratte Brothers; commissioning management Commtech; lifts Kone Lifts; terracotta retail facade fixing Szerelmey; terracotta supply NBK (Germany); shopfronts, window replacement, main entrance screen and rooflights, louvre screens Exterior Profiles; facade cleaning equipment Cradle Runways International; internal block walls Irvine Whitlock; chilled ceilings
CLIENT J Walter Thompson
INTERIOR DESIGNER DEGW: Holli Rowan, Terry Gunnery, Alison White, Jan Young, Wynne James, AlanGriffiths, Jacqui Surtees, Teresa Jackson, Philip Muir, Gemma Fabri, Matthew Marcroft
MAIN CONTRACTOR Bovis Lend Lease Interiors
PROJECT MANAGER J Walter Thompson; Ian Gordon, Michael Beiley
Prudential Property Investment Managers www. prupim. com
Hurley, Robertson and Associates www. hra. co. uk
Gardiner & Theobald www. gardiner. com
Waterman Partnership www. waterman-group. co. uk
Roger Preston & Partners www. rpreston. com
Bovis Lend Lease www. bovislendlease. com
Randle Siddeley Associates www. randlesiddeley. co. uk
Arup Facade Engineering www. arup. com J
Walter Thompson www. jwt. co. uk
DEGW www. degw. com
Moffat Communications www. moffat. co. uk