Ian McArdle reaped the reward of good design when he upgraded Foster + Partners’ ITN headquarters in London, a building he had long admired
A quarter of a century after it was completed, it’s a credit to the original designers of 200 Grays Inn Road that its first tenant, ITN, still shows no sign of wanting to move. When it opened in 1990, its London HQ, designed by Foster+Partners, was a state-of-the-art office block, combining the heavy servicing needs of a fully functioning newsroom and studio at lower levels with high spec speculative offices above. With its outer form dictated by the run of the streets to the east and west, the building came complete with a huge tapering internal atrium that ran from the existing basement level up to its eighth floor glazed roof. Fitted with high performance, ventilated cavity curtain walling on all sides, to the south an enormous full height opaque glazed ‘cathedral wall’ flooded the atrium with light while combating the worst effects of solar gain. When it was sold in 2011 to Great Ropemaker Partnership an upgrade was in order. Ian McArdle Architects, who worked with AHMM on a number of projects including the Stirling Prize-nominated Angel building, was appointed to propose a staged refurbishment of the 26,000m2 building.
The brief includes, over time, the full stripping back of all the floors, which means removing all the original suspended ceilings, raised floors, perimeter blinds, doors and atrium glazing and making a proposal for their replacement. ‘When this building was completed, I had just left Grimshaw and I remember thinking it was iconic,’ recalls McArdle. ‘It was Fosters’ first building in London, fitted with the most amazing cladding, and I thought it was the bees knees.’ His excitement increased when he actually got inside the concrete-framed building and the strip-out started in earnest. As they tore away the suspended ceilings, beautiful raw concrete coffers were revealed beneath. McArdle says the intention had been to install new ceilings, but once they saw the coffers, they knew the only approach would be to predicate the air handling and lighting strategy on their permanent exposure.
Considering the future
The building’s level of future-proofing made the adoption of the new air handling strategy relatively simple. First, explains McArdle, the 9m by 4m Gartner glazed cladding originally specified for the facade was a rudimentary form of ventilated cavity. This was designed to improve the thermal performance of the cladding; in winter pumping exhaust air into the cavity to reduce net heat loss from the office, and in summer purging the cavity of hot air with fresh to reduce the effects of solar gain. This system was renewed, but reinstated. The big change was that the air handling strategy went from Variable Air Volume to a displacement system, typically requiring less cooling energy than the former due to the supply air temperatures involved. Crucially, it also moved from ceiling to floor-fed – all helped by the original raised floor zone.
As they tore away the suspended ceilings, beautiful raw concrete coffers were revealed beneath
McArdle says that the response from potential tenants has been positive. He notes that the number of cores in the building gave it an innate flexibility in terms of space planning, although the exposure of the coffered soffit has to some extent put a limitation on this (floor tenancy splits on grid line 12). That said, efficiencies have been increased as demanded by the market. McArdle says that inherited net to gross efficiencies were typically 70%; now on the first floor east side they’re up to 84%, despite the fact that he concedes that total net area was reduced with extra space given over to the new displacement plant on two of the cores.
The result is a building that has, with thought and consideration, been upgraded in a way that plays to the its original strength – the structure itself. In the process it’s risen from a ‘D’ to a ‘B’ rated building and has a new-found sense of space and light. But McArdle modestly concludes that the moves made seemed totally in keeping with the spirit of the original. ‘All we had to do was fix everything and the building went from 1990-2013 in little more than a hop, skip and a jump,’ he says. •
In the lift lobbies white Barrisol stretch ceilings increased heights by a further 700mm, lending extra grandeur to the public areas
‘Fosters built in a 380mm raised floor void – huge at the time, but it would have aimed to predict future data management needs in the absence of fibre optic technology,’ says McArdle. ‘With cabling requirements actually a fraction of that assumed requirement, and with the suspended ceiling removed, our decision was a “no-brainer”: we fed the displacement air into the offices through the raised floor void’. Air is now fed into the spaces at 18ºC and expelled through the atrium at 23ºC via upgraded fan coil units that work in parallel with displacement AHUs, their casings now exposed on the atrium side, giving the offices a stripped-down, jet-set feel.
Exposing the ceiling had knock-on effects for other services too. Along with McArdle’s wish to remove all the original high-level sprinklers came the requirement for a commensurate upgrading of the building fabric. This had to be done on both the atrium and external faces; which on the external face meant reducing the amount of glass on the facade. Since this is an integrated floor to ceiling curtain walling system, you’d assume this would be catastrophic for the aesthetic, but it turns out there was a serendipitous solution.
‘The fire officer demanded that a 900mm strip of every facade be given over to fireproofing – an onerous requirement,’ recalls McArdle. ‘Luckily, the east facade already incorporated a 780mm overpanel: we asked if it would be enough to do something with that, and she accepted.’ The firm removed the panels, installed Promat Superlux boards behind them, and screwed them back into place using the same holes. ‘Even after the fire upgrade, you can’t notice the difference,’ he says, adding that on the atrium side, the non-fire rated single glazed sheets were exchanged for FR30 glass. The new fan coil units, which hourly
purge the offices of spent air, are programmed to kick-in, should fire break out, and dump smoke into the atrium to be vented through its glazed ceiling, as per the original strategy.
With all of this invisible intervention, it’s good to see that IMA has managed to leave its own mark on the refurbished floors, and that’s through the new lighting strategy. In place of conventional suspended ceiling luminaires, the firm has instead really brought the coffers alive with an ingenious anodised aluminium lighting ladder that fits snugly within them. Developed with lighting firm Zumtobel, they also incorporate emergency lighting, passive infra reds, emergency signage and smoke detectors. The downlight component comprises two bold circular LED luminaires per coffer, whose simplicity seems at home in the concrete.
McArdle explains that they had more problems with the uplighting component. Trying to achieve the requisite upward wash without splaying the sides of the aluminium frames didn’t sit well with the simple aesthetic of the frame. The firm settled instead on pulling the strip fixtures a little proud of the frame to achieve correct wash levels. The result is a floor to ceiling height that’s 3.4m to the bottom of the coffer and 3.7m to the top – generous by any standard. The same approach was adopted in the lift lobbies where white Barrisol stretch ceilings were installed and heights increased by a further 700mm. This lends extra grandeur to the public areas, although it also meant the slightly irksome revelation that the white painted concrete is not in fact white but contains the merest hint of green; a repaint of the whole interior was not part of the refurbishment spec. Fortunately the Kaim cementitious stain, used to remediate newly exposed concrete faces, was.
Drop the dead deadline
Grant Brooker, senior partner, Foster+Partners
When designed in 1990, the ITN HQ was first and foremost a media building, and the idea of opening up the inside to the world through huge glass walls was part of the bigger idea of communication. It was an intriguing site – the Sunday Times had owned it and had printing presses in the basement, giving great potential for media industries to re-use them. Apart from huge 9m by 4m Gartner glazing panels, and the massive tapered atrium, this building was all about the concrete frame. It dictated almost everything about it.
The construction programme was incredibly quick, which drove everything from the size of the cladding panels to the logistics of the pour. In under two years we would demolish the old building, get planning permission, construct and fit it out. We had already specified the 11 lifts before we even had planning permission. And by the time we were casting the slab on the second floor, ITN was fitting out the basement studios. Ray O’Rourke had the entire concrete frame up in 26 weeks – unheard of at the time.
Nothing was tendered and everything contracted; we only approached contractors and manufacturers that we knew could deliver this kind of accelerated programme. The consultants and contractors turned out to be incredibly collaborative. It was an exciting period where we were all pushing expectations to deliver a complex media HQ and highly flexible office space faster than anyone thought possible.
Suspended ceilings were installed, but we felt it was robust enough to have them or not. With budget and time running out, we did paint the concrete; not white, which we felt was too stark in the light of the south wall, but very very pale grey-green.