How Coffey Architects’ Digi-Tech Factory delights

‘Architecture should be light, bright and joyful,’ according to Coffey Architects founder Phil Coffey. That’s true of Digi-Tech Factory, an eye-catching new teaching building by the practice for City College Norwich.

He hopes its delicate, white appearance, achieved with the use of an aluminium mesh screen as part of a double-skinned facade, will bring a ‘bit of delight’ not only to the 500 students who will study there but to those using the campus in general.

‘Architecture can lighten things up both experientially and aesthetically,’ he says, keen to encourage a sense of optimism.

Screens have become something of a regular motif in the practice’s work, most recently at the 22 Handyside Street offices at King’s Cross and in housing for London Square in Bermondsey. All exemplify the practice’s long-held interest in the manipulation of natural light through depth and layering.

At Digi-Tech Factory, the screen plays ­important functional and aesthetic roles, with the control of light a key priority, especially for a building serving the college’s technology, engineering and design courses.

‘The building’s full of computers. Moderating light and glare is very important,’ says Coffey.

Situated at the entrance to the City College Norwich campus, the 2877m² building needed to fulfil a secondary role as a welcoming public face.  Alongside the black timber-clad Creative Arts Building – designed by BDP in 2013 – the distinctive whiteness of the Digi-Tech Factory certainly creates something of an ebony and ivory moment.

Coffey was keen to create a building that not only combined specialist teaching facilities and flexible, general working spaces but encouraged social interaction through the provision of both internal and external informal social spaces. The practice visited a number of higher education colleges with less institutional atmospheres as part of its research. The result was the idea of a factory, a narrative referenced externally with the saw-tooth roofline.

The site is bounded on the east by an impressive mature cedar tree. To the west is the Creative Arts Building. Accommodation is arranged on four levels, with a sheltered piazza for outdoor socialising formed by a lofty undercroft adjacent to the tree. Students pass through the undercroft to access the main entrance, with links at ground, first and second floor levels into the neighbouring Creative Arts Building.

The lofty, largely glazed ground floor accommodates teaching space for electronics, robotics and hardware. At the south of the building, corrugated aluminium panels by ArcelorMittal clad laboratory accommodation.

On the upper three floors, classrooms are arranged around a generous central corridor with break out spaces for hot-desking and socialising. The top floor studios benefit from the extra height and light of the saw-tooth roof. Double-height light wells enable further visual transparency through the building.

‘We worked the budget very hard, not in terms of expensive finishes, but in terms of the spaces the architecture creates,’ says Coffey.

Key to this is the effect of layering and perforation created by the double-skinned facade, which allows the architect to deal with the light issues as well as creating what he describes as a playfulness through the treatment of the ‘shroud’ of the screen.

Coffey says the use of a double skin was a bold decision: ‘There’s twice the material to achieve the layered facade, so you have to get it right in terms of transparency, depth, composition and finish.’

The main structure is an exposed steel frame with a concrete floor deck. For the thermal barrier inner skin, the architect’s research into off-the-shelf carrier panel products used for large-scale industrial sheds led to a specification for Eurobond Rockspan, a lightweight composite steel-faced insulating panel with an average size of 750mm wide and 3500mm long.

The panels cover approximately 70% of the inner facade layer, which is completed by judiciously-placed curtain wall glazing, Kawneer’s AA100 product.

The outer layer is a screen of aluminium mesh. Raised one storey on steel columns, this gives a unifying appearance, covering approximately half of the glazed area as required – on the north elevation for example only 40% is covered by the mesh.

The screen – made by Imar through Just Facades – comprises 750mm wide panels that vary in height from 3000-3500mm. Each is folded 75mm along the long edges to increase rigidity and strength, with the folded ends facing outwards to create a series of ribs that add texture to the facade. The panels are side-fixed at 500mm centres into a continuous vertical T-profile mullion. This is supported at each floor level using aluminium saddle brackets, which connect back to the inner envelope and steel frame.

A great deal of attention went into the bespoke design of the screen, in particular the size of the laser-cut perforations, with the architect conducting tests with varying sizes when viewed from various distances.  The final design is an arrangement of 16mm perforations with a 1mm radius, with 6mm spacing. As well as their role as light screens, the perforations are conceived as a reference to binary code and historic computer tape.

The aluminium is polyester power coated in white RAL 9100. As well as being striking visually, the all-white colour of the facade has the advantage of being more forgiving of any potential inconsistencies. The interior is also largely white, with some flashes of yellow highlights.

The architect varied the distance between the two layers to get the lighting effect it wanted for each elevation – for example this ranged from 225mm for the north, south and west elevations to 750mm for the east.  Where the screen is used to enclose the ground floor plaza and colonnade, the distance is respectively 12000mm and 2850mm.

Inside, the light is softened and diffused during the day, with large enough perforations to enable good views out. A night, the elevation is highlighted with illumination from spaces within the building. Fixtures on the inner layer are exposed and visible through the screen, an approach carried through to the inside, where the structure and services are also exposed.

‘We wanted to achieve something that looked veil-like from a distance and read more like a mesh closer up,’ says Coffey.

Although half the proposed saw-tooths in the roofline were lost to maximise cost efficiency, the external effect still creates a distinctive skyline. Coffey is pleased that Digi-Tech Factory ‘feels like a crafted building’ while at the same time being ‘humble and straightforward’.

The project achieved BREEAM Excellent at Stage 3 design stage. Completed on a tight schedule of just two and a half years from tender to completion, despite the pandemic, it is the first to be completed as part of the government’s Town Deal programme, which part-funded it.