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Once reviled by critics for trampling all over the historic character of some of the most sensitive parts of London, the architectural reputation of Richard Seifert is slowly being rehabilitated. This was the man who introduced the high-rise commercial office block to Britain, with his practice responsible for Centrepoint, Tower 42, No 1 Croydon and the Tolworth Tower among many others.

Although many of his buildings will always attract opprobrium, the high-rises have fared rather better, with three receiving grade II listing. The only buildings from the office of R Seifert and Partners to be listed were all designed by founding partner George Marsh.

The most famous of these 鈥� Centrepoint, by Tottenham Court Road Tube station 鈥� was converted into flats in 2018, and Birmingham鈥檚 Alpha Tower was recently refurbished. The third in the trio, Space House, has just undergone a major refurbishment.

>> Also read: The notorious work of Richard Seifert

Although less high profile than Centrepoint, Space House bears many similarities. Both were developed by Harry Hyams, who achieved notoriety for leaving Centrepoint empty for 10 years while property values increased. Space House was empty for seven years until it was let to the Civil Aviation Authority, which occupied the building continuously until 2019.

Both buildings spurn orthogonal form; Centrepoint features distinctive curved long sides and Space House is cylindrical. And both buildings feature flamboyant, angular precast facades which provide solar shading for punched windows.

The facades were formed from modular units 鈥� T sections in the case of Centrepoint and cruciform sections for Space House 鈥� and are structural. Ahead of their time, both buildings were the first to be built in London without scaffolding.

Centrepoint featured a low-rise block to the east connected to the tower with a link bridge. This arrangement repeats at Space House; a low-rise rectangular block addresses Kingsway and is connected by a link bridge to the tower behind on Kemble Street.

When Space House came available, I fell in love with the building as it is a stunning piece of architecture

Tyler Goodwin, chief executive, Seaforth Land

And, in another connection, Almacantar, the firm that redeveloped Centrepoint,  also owned Space House. Rather than refurbishing it, however, they decided to sell the building to small developer Seaforth Land, whose chief executive Canadian Tyler Goodwin has a penchant for buildings of that era.

鈥淲hen I came here about 10 years ago, I was surprised that 鈥� as opposed to North America 鈥� mid-century buildings aren鈥檛 particularly loved here,鈥� Goodwin says. 鈥淲hen Space House came available, I fell in love with the building as it is a stunning piece of architecture.鈥�

Seaforth has refurbished several London buildings 鈥� reuse is a strong driver for Goodwin 鈥� and he is proud of the fact that Space House will be the first listed building in London to achieve BREEAM Outstanding, which is no mean feat for a building of this vintage. Space House is the biggest project that Seaforth has tackled; how did it get on?

The building had been chopped and changed during the CAA鈥檚 44-year tenancy which included two major refurbishments. Maintaining Seifert鈥檚 design intent was not a consideration. The building had been designed to be naturally ventilated with openable windows with ventilation shafts in the core to pull air into the building through the windows. Instead, the CAA retrofitted air conditioning.

鈥淭he air-conditioning units ended up just piling up on top of the building over several decades, so that the entire silhouette of the building was wrecked,鈥� explains Tim Gledstone, partner at Squire and Partners, the architects for the refurbishment. Ceiling tiles obliterated the distinctive radial ribbed concrete soffits and truncated the windows.

The transparent, open quality of the Kingsway block had been compromised by an enclosure around the staircase at the south end. The north stair, which featured distinctive terrazzo cantilevered treads, had been replaced by an inappropriate stainless-steel version. And the entire site was blocked off by security fencing.

Permission was granted to add two extra floors to the building as the overall height will be unchanged once the forest of telecommunication masts and air conditioning are removed. This also creates space for air source heat pumps on the roof, which will be hidden from view.

The lower floor is a facsimile of those below and the top floor is set back with a terrace and 360-degree glazing. There was an observation deck at the top, but this had become obscured by the aircon units and masts.

A setback extension is also being added to the Kingsway block. Again, the height will remain unchanged as there was already a small single-storey plant room on the roof.

In a throwback to the days when the car was king, the building included a huge 200-space, two-storey underground carpark, with three access ramps to cope with the volume of traffic. The building even included its own filling station sheltered by a cantilevered, saw tooth-edged canopy.

Two of the ramps have been removed, leaving one for cyclists accessing one of the 610 cycle spaces, and part of the intermediate basement slab has been removed to create a double-height events space.

Floor to ceiling glazing has been inserted behind the ring of Y-shaped pilotis supporting the tower. This creates a doughnut-shaped reception thanks to the circular core. The filling station canopy has been integrated into this space by extending the glazing to the canopy edge, creating room for a restaurant.

Gledstone and Goodwin say the building鈥檚 environmental design fundamentals are very good. 鈥淲hen we started modelling it, we found that it was a very well performing building,鈥� Gledstone says.

Natural light levels are good thanks to the generous windows and shallow-plan floorplates. The deep precast facade provides effective shading. 鈥淲ithout that shading, I think it would have been impossible to get BREEAM Outstanding,鈥� Goodwin says.

The original single-glazed windows have been replaced with double-glazed versions. The solid panels at the base of the windows have been replaced with glazing featuring a mesh interlayer which increases light levels inside the building without compromising the external appearance.

Like the originals, the windows are openable, with the difference being that these are operated by the building management system. The windows open at night when the outside temperature drops below 16.5掳C at midnight to cool the exposed concrete soffit.

On days when it is cool enough to dispense with air-conditioning 鈥� which is a lot of the time in the UK 鈥� tenants will need to opt in to mechanical cooling. This is provided using passive chilled beams neatly fitted between the ribs of the soffits.

I would like to be able to say, with our tenants, 鈥�congratulations, we鈥檙e now the only mid-century modern listed BREEAM Outstanding, six-star office building in the world鈥�

Tyler Goodwin, chief executive, Seaforth Land

Goodwin says the building鈥檚 smart technology will help to reinforce positive behaviour. 鈥淥ur technology will send a notification to employees as they leave at the end of the day. If they are an employee on a floor that didn鈥檛 have the air-conditioning on, it would say, 鈥�congratulations, you did your part by not having your air-conditioning on and you鈥檝e significantly reduced your operational carbon鈥�,鈥� he says.

His ambition is to achieve a 6* NABERS rating for operational performance, an extremely challenging target even for high-performance, new buildings. 鈥淭he experts told us when we started that there was no way this can be a BREEAM Outstanding building. They said to forget about it, it will never happen. We鈥檝e also been told there鈥檚 no way that we can be NABERS 4.5 star, which is what we achieved in the design stage,鈥� he says.

鈥淢y goal is that this building gets to six stars. I would like to be able to say, with our tenants, 鈥�congratulations, we鈥檙e now the only mid-century modern listed BREEAM Outstanding, six-star office building in the world鈥�.鈥�

So, who are the tenants that would want to take space in a 1960s mostly naturally ventilated building? Goodwin says the statistics suggest it will be younger workers. Gen Z and millennials already make up 56% of the London office workforce, a figure that will increase to 68% by 2030.

Goodwin believes refurbished office buildings like Space House, with their solid environmental credentials, will appeal to those young workers. 鈥淭his generation is more concerned about values and purpose in an organisation,鈥� he says. 鈥淲hat are they doing about the environment? What are their commitments?鈥�

He adds that the building鈥檚 architectural history is less important than its physical appearance. 鈥淭enants don鈥檛 think as much about heritage credentials as they do authentic experiential architecture.鈥� What they will respond to is its appearance and style. To that end 1960s finishes such as terrazzo floors flow through the building.

One highlight is the marketing floor, which has been fitted out in an authentic period style. Goodwin says there will be a couple of food trucks parked on the building鈥檚 public spaces from noon to 3pm each day and there will be live music too. Continuing this theme, the reception desk will incorporate a turntable playing period music on vinyl.

鈥淭his suggests that this place is different; it鈥檚 cool. How many buildings have a record player at the reception?鈥�

This distinctive quality will stand out in the heads of potential occupiers, Goodwin says. 鈥淚t鈥檚 like, that鈥檚 the round building with a record player in the reception.鈥�

This factor was probably not in the minds of the commercially driven duo of Hyams and Seifert in 1968. But, over half a century later, the architectural qualities of Space House 鈥� a name inspired by the optimism of the Apollo moon landings but forgotten by the CAA 鈥� have been allowed to shine.