Crucial to the success of the £239m greenfield project was the design and specification of the 4800 doors, 1640 windows and 6000 m2 of curtain walling. This would determine how deeply daylight penetrated the interior. Naturally, considerable co-operation between contractor and architect was necessary, according to project architect Dick Mitchell. "Having a contractor on board early curtails design freedom to an extent," he admits. In a traditional JCT contract, the drawings are at a much more advanced stage when the main contractor is chosen.
The hospital's doors and windows package was let as a competitive tender according to performance specifications stipulated by Anshen Dyer. The glazing packages included design, manufacture and installation. This meant that while the architect produced concept drawings, most of the detailed drawings and product selection were done by the specialist subcontractor.
Anshen Dyer specified aluminium-framed glazing for the external elevations. The architect did not bother with complex whole-life-costing calculations – instead, Mitchell says, aluminium was chosen for most of the windows and curtain walling because of its lifespan and low price compared with steel.
The windows specification was complex, because the hospital had so many rooms with different functions, each requiring different types of windows. Depending on a window's position, it might have to be fire-rated and fitted with safety or solar glass.
However, Laing and Anshen Dyer were able to trim the cost of the windows by specifying more expensive glass only where required by the Building Regulations. For example, safety glass must be used for all panes less than 800 mm from the floor. Laing was also careful only to specify expensive solar glass for the windows and curtain walling of south- and west-facing elevations.
The competitive tender for the curtain walling was won by local firm English Architectural Glazing (EAG). EAG also tendered for the windows package but this was given to Belgian glazier Rewa. No contractor would have won both packages because Laing operated a dual sourcing policy to ensure that if one firm was unable to complete its contract, the other company could finish the job. The wisdom of this was demonstrated when, halfway through the programme, EAG took over the works package of 1600 unfinished windows with only minimal delay.
When EAG was awarded the curtain walling package, it made detailed drawings based on Anshen Dyer's concept drawings. Complex factors such as wind loading had to be taken into account, as did the performance specification's requirements on interstitial condensation, thermal and acoustic performance, maintenance, wind deflection and air leakage. Anshen Dyer checked the contractors' final drawings before fabrication began.
EAG and Rewa chose the aluminium Schüco system, which comes in 6 m long sections and can be made to form any size of frame. The final choice of colour and frame design was made once Anshen Dyer and Laing had seen a number of sample panels provided by the glaziers. In the end, a grey polyester powder-coated finish was chosen to complement the brickwork.
According to EAG's Simon Gladwin, the biggest issue wasn't the design of the curtain walling but the scheduling of the job on site. EAG was given the timeframe it had to work in, so Laing could fit EAG's installers in with the other trades working in the same vicinity. "We ended up working on 15 areas at the same time, which was a logistical nightmare," says Gladwin.
The finish of the internal doorsets was determined by Anshen Dyer, which specified timber doors to give the interior a warm, natural feel. This decision was initially questioned by Anshen Dyer's US head office, which believed the door frames should be constructed from steel to withstand damage from trolleys and other hospital equipment.
"As the door frames are wide, there shouldn't be a problem with trolleys," says Mitchell, adding that "steel also looks badly damaged when it is bashed into". There was also a cost disincentive to using steel frames with timber doors. In the UK, fire tests have only been carried out on doors and frames of the same material. If Anshen Dyer specified steel frames with timber doors, the PFI consortium would have suffered the cost and delay of getting them specially tested.
A wide array of door types was specified. For example, operating theatre doors had to be coated with easy-clean plastic laminate and toilet doors had to swing outwards in case an unconscious patient had to be rescued from a cubicle. There were also fire-rated doors, lead-lined doors for X-ray rooms and acoustic doors for speech therapy rooms. Laminate was specified for doors subject to high impact, although the softwood doors were protected on each edge by hardwood lipping. In general, double-action swing doors were used in corridors and single swing doors were fitted in ward areas. Leaderflush + Shapland won the competitive tender to supply the 4500 doorsets. It was named as a preferred supplier in the tender – partly because it was one of the few manufacturers capable of supplying so many doors.
Laing arranged for the doors to be installed after the vinyl flooring had been laid. Leaderflush + Shapland project manager Andy Gregson said this decision helped explain why Laing had to reorder so few doors. "Installation of doors at a late stage of construction reduces the risk of damage and ensures a more controlled environment where humidity is at the right level. We recommend that the contractor should always get the floor down before installing the doorsets," he says.
For the internal timber doors, Laing and Anshen Dyer chose Orbis 8 door handles from IR Laidlaw. The range is suitable for high traffic areas and the silk-anodised aluminium finish closely matched the aesthetic of the door. Orbis 9 door closers in the same finish were chosen to complement the handles. IR Laidlaw also provided the electro-magnetic devices the keep doors open in busy corridors. In the event of a fire, electricity would be cut to the devices and the doors would close.
As well as being three months ahead of schedule and on budget, the hospital strongly resembles Anshen Dyer's initial designs. What's more, it has become the first PFI hospital scheme to get the thumbs-up from architectural watchdog CABE, which praised the logical layout of the hospital and the way the architect had introduced natural daylight into much of the building.
It’s only natural: maximising daylightGetting natural light into the hospital was particularly challenging because planners restricted the buildings to four storeys. “It’s easier to get light into wards if they’re in a tower block,” says project architect Dick Mitchell of Anshen Dyer. The wards were designed to capture more daylight than other rooms as that is where patients spend most time. The nine ward blocks are turned 45º to the main hospital building to enable punch windows to be installed on all four elevations. Where day rooms are situated at the ward corners, Anshen Dyer has used glazed curtain walling to allow maximum light. Many of the ward windows are double height, to give patients a good outlook from their beds. “Floor to ceiling windows give patients views of the countryside and not just the sky,” says Mitchell. Open courtyards between the wards and the main hospital buildings ensure that daylight floods into the rear of the wards. Two large atriums at the main public entrances to the hospital feature curtain walling made and installed by local glazier EAG. The atriums introduce light into areas where visitors and staff are likely to congregate. At the heart of the hospital are the diagnostic and treatment areas, many of which have windows. “Surgeons like light. If they’re operating for six hours at a time they can suffer eye tiredness. Looking out of windows helps to relax their eyes,” says Mitchell. Most of the windows can be opened but for safety reasons restrictors prevent them opening more than 100 mm. Trickle vents provide ventilation when they are closed. Windows in sterile areas and in rooms containing sensitive equipment have blanking plates fitted over the vents to stop air entering the room. All the punch windows have wide mullions to allow flexible room dividers to abut the window frames. Anshen Dyer was keen to maintain simple elevations of the buildings and hide any medical detritus. For example, opaque infill glass panels have been used to disguise the building structure and unsightly hospital equipment in the day rooms attached to wards.
Architect Anshen Dyer Main contractor Laing Curtain walling and window subcontractor English Architectural Glazing Brises-soleils Merlin Steel fire doors Cape Automatic doors Dor-O-Matic Internal doors Leaderflush + Shapland Door ironmongery IR Laidlaw Windows, curtain walling and window ironmongery Schüco Solar glazing Coolite