Allies and Morrison’s 100 Bishopsgate: ‘The first of its kind… and maybe the last’

2/7/21

'It goes from Medieval to Miesian,' says Allies and Morrison's Graham Morrison, as we contemplate 100 Bishopsgate's faceted glassy form rising above us. The building morphs from a parallelogram-shaped footprint at ground level – generated by the angles of the original Medieval street pattern – rising to glassy four-square office floorplates nearer its top, 40 storeys above. To take a tailoring analogy, these angled facets in its envelope twist its form from spreading skirt to tightly fitted torso. 'The shaping is intended to make it less overbearing,' says Morrison. Certainly, unlike PLP's 22 Bishopsgate behemoth currently completing down the street, it doesn't loom quite so large, for all that it's a 1 million square foot, 181m-high building.

Morrison is keen to dispel any suggestion that the shaping is wilful or expressive. He recalls how Peter Rees, the City of London's former chief planning officer, referred to the cluster of towers that emerged on his watch as a 'toy box' of shapes, more Sherriff Woody and Buzz Lightyear than Gherkin, Walkie Talkie, Cheesegrater, Can of Ham, Scalpel (a litany of nicknames that sounds like some crude survival kit). In fact, with no New York-style calibrated set-backs, the cluster has increasingly solidified into a single formless lump, viewed from afar. 'With all these competing shapes, we resisted doing the extraordinary,' says Morrison. 'You could say ours is a wooden block in the toy box in contrast.' This perhaps doesn't surprise from Allies and Morrison, known for its well-mannered modernism over the past 25 to 30 years, even, whisper it, for buildings that are slightly dull. But, however shy and retiring among the overbearing company, 100 Bishopsgate is still a huge glass-and-steel office tower, a building type in the crosshairs of critical scrutiny these days, with question marks over its continued viability environmentally, functionally and economically in a world beset by the challenges of climate breakdown, Covid-19 and, for the City at least, Brexit fallout.

Operational efficiency has often been used to warrant mechanically moving people vertically up and down in densely occupied towers, and 'wellness' used to justify cladding floors wall-to-wall in glazing with little concern for orientation. But today's focus on reducing embodied energy in construction has cast into relief the material excesses of building towers, however operationally efficient. Tim Snelson of Arup, writing in Domus, calculated that skyscrapers have double the carbon footprint of 10-storey buildings of equivalent floor area. Even the best option to mitigate this – using timber structures – is no longer an option in the UK, due to fire concerns post-Grenfell.

In addition, the coronavirus pandemic has shown how workable home working (for those able) can be, questioning the need to commute. While reports of the death of the office are no doubt exaggerated, London's vacant office space is predicted to hit 10 per cent this year, putting more pressure on commercial lets in the City, already under pressure from loss of access to European financial markets after Brexit.

So, while this is a newly minted building, in a sense it harks back to a different era. Great Portland Estates lodged its planning application for the scheme in 2006, a decade before the Brexit vote and two years before the 2008 financial crash. Financial services were booming and City-based firms were looking to expand at Canary Wharf due to the shortage of space in the Square Mile. This led the City of London to approve the redevelopment of a rash of larger sites with ever-taller buildings. The site of 100 Bishopsgate is on the south-east corner of where Camomile Street meets Bishopsgate, a busy junction since Roman times, marking the point that the latter, then called Ermine Street, passed through the gates of London's wall, en route for York.

The dense mix of buildings on the site, owned by the Leathersellers' Company, was badly damaged by the Bishopsgate truck bomb, planted by the IRA in 1993. The event is memorialised by the adjacent, scarred shell of the tiny medieval St Ethelburga's Church, now a Centre for Reconciliation and Peace. The Leathersellers' Company sold the leasehold of the site to Great Portland Estates in 2010 in a deal that saw the latter pay for the rebuilding of its Livery Hall (to a design by Eric Parry) in St Helen's Place. Following site clearance, a single two-acre plot of land was created, with Bishopsgate to the west, Camomile Street to the north, St Mary Axe Street on its eastern flank and southern edge on St Helen's Place.

Allies and Morrison, having won the scheme in competition in 2005, developed an overall parti consisting of a 40-storey tower sitting on a five-storey podium and a smaller, seven-storey building, 15 St Helen's, fronting the mews behind a retained façade. The key move for unlocking the site is a vast two-storey basement, entered off St Mary Axe, which services all the buildings. 'It's like an underground service yard,' says Jo Bacon, the Allies and Morrison partner in charge of the project. Above this, a new pedestrian passage, Clerks Place, has been created, running from Bishopsgate to St Mary Axe, off which a spur passage under the podium building connects to Camomile Street. This public realm permeability has always underpinned the practice's narrative for the scheme. Tellingly, the key competition drawing they make reference to is not some lofty elevation but Morrison's sketch of the pedestrian routes criss-crossing the ground plane.

The bridging of the five podium floors across the whole depth of the site also enables the building to provide 4,100m2 Canary Wharf-scale trading floors. 'It's the first of its kind: a new generation of offices able to offer that kind of space in the City of London,' says Morrison.

This overall parti has survived pretty much unchanged since, even after the shockwave of the 2008 financial crash saw Great Portland Estates sell the majority share of the site to American developer Brookfield in 2011. At that point, Woods Bagot was brought in to review the design, subsequently taking on the role of co-architects. It seems to have been a remarkably amicable partnering with Allies and Morrison. Earle Arney, originally of Woods Bagot and who now leads on the project for his company Arney Fender Katsalidis (AFK) (successor to Woods Bagot) points out: 'It's a design with inherently "good bones" and flexibility: we identified opportunities to optimise floor space and façade design and simplify the core.' Morrison acknowledges that the North American know-how Woods Bagot and subsequently AFK brought improved the scheme, with the latter suggesting changes such as moving service duct access to the core to increase the usable floorplate. After a pause between 2012 and the end of 2014, the scheme finally went on site in 2015.

On approach, the western façade to Bishopsgate has a distinctive, articulated appearance, compared with the glassier surfaces of adjacent blocks. Its gridded aluminium veil acts as a brise soleil to reduce solar gain (although this is missing on the south façade, rather undermining the design intent). At street level, a 5m-high colonnade of tubular stainless steel columns, sheathing the steel frame, has a touch of corporate bling, but also brings a soft, '70s feel to how the tower hits the ground. On opposite corners two columns are set at an angle in line with the rake of the façade above, providing an expressive punctuation to the otherwise static orthogonals. Inside the columns the glazed lobby weaves more sinuously: 'On plan, we describe it as an Aalto vase,' says Bacon.

Sets of entrance doors ring the lobby, allowing a primary tenant (currently Royal Bank of Canada) to carve off its own lobby to one side of the central core. The main shared entrance leading off Clerks Place is positioned for visitors to pass the nicely contrasting backdrop of St Ethelburga's Church. While the half-acre of public space touted in the publicity feels more like the minimum necessary threshold around the tower, a number of double-height retail units in the base of the podium promise at least branded animation to these spaces when life returns post-pandemic.

Entering, the space plays on the stereotype of luxe corporate lobby: a massive honed marble-faced lift core backs the reception desk. The stone, sourced and laid as cut from the single face of an Italian quarry, is minimally detailed, appearing to rise from below and disappear above. It's evidence of what Bacon calls the 'refining and paring-back' of detail in the scheme. 'We aimed for a sense of timelessness, something not overwrought,' adds Morrison. With only 350 of the 9,000 passes issued for the building in regular use at present, the intended grandeur here is a little mausoleum-like in atmosphere (more tomb than monument, to misquote Adolf Loos).

This spareness continues on the upper floor plates: requisitely vast and column-less around the core, the framing of the spaces is limpidly simple, excess detailing cut to a minimum.

The material paring-back was not just an aesthetic strategy but also the result of a drive to fabricate as much off-site as possible to minimise waste and divert at least 90 per cent of the detritus from landfill, in addition to sourcing materials responsibly.

Operationally, too, the building does what you'd expect environmentally and wellness-wise, at least for a scheme designed more than 10 years ago. It offers 900 bike spaces, has PVs on the roof (if covering just 1 per cent of energy use) and there's a SuDs water attenuation strategy. All contribute to significant resource and energy reductions and the scheme is rated BREEAM Excellent.

A roof terrace was added to the top of the podium during construction. This feels almost like a room, enclosed by the Gherkin and other towers, echoing the Arc de Triomphe-as-mantelpiece conceit of Le Corbusier's roof terrace on the Beistegui Apartment in Paris. The terrace only serves its adjacent office floor but, asked how they would do things differently if designing the building now, Morrison says: 'Incorporate more outside space; plan for an alternative use; and, of course, start with a whole-life carbon assessment.'

This scheme can plead its long genesis in side-stepping the pressing questions around embodied carbon when building today, although, compared with this elephant in the room, incremental moves to improve operational efficiency can seem akin to rearranging the deckchairs on the Titanic. Nevertheless this is a well-detailed building, high-ceilinged, with flexible, open floor plates and a 60-year-plus life span, which should at least ensure a long life, loose fit in whatever guise.

Changes of use in cities will not happen overnight and many of us will return to offices once the pandemic subsides. But, interestingly, Brookfield has put the building up for sale. It is 'set to become UK's most expensive office', according to The Guardian. Whether this is a breezy show of confidence in the much-touted bounce-back of the office market or the offloading of a no-longer profitable long-term asset is a moot point. As Arney says, gnomically: 'Investor risk versus climate risk have become more aligned of late.'

Tellingly, Morrison, in the same breath with which he describes 100 Bishopsgate being the 'first of its kind' in the City, adds: 'Of course, it may be the last of its kind, too.'

Architects' views

This has been a significant project for our practice, and we are proud to have delivered it, all these years after the initial competition and yet delivering the original ideas. It has involved a positive collaboration of many people over 15 years.

The building transforms the historic junction of Bishopsgate and Camomile Street to welcome people across a now-open, accessible site, while achieving a clarity and simplicity of form both externally and internally. This is a project that is complex in what it delivers – complex at ground level and in its detailing. But, guided by Brookfield's approach, it is bold in its simplicity and confidently holds its place in the City cluster.

It is the ground level in particular which this project is very much about. More than just the tower, we have an ensemble of three pieces that work together to create a more urban whole, incorporating a five-storey podium that extends along Camomile Street and the adjacent 16 St Helen's Place. These frame and shape new walkable routes but also deliver new trading floors for the City and a rooftop garden.

We were ambitious for lots of active ground-floor uses in the form of retail space (about 4,200m2), which are due to come alive as soon as London emerges from the pandemic. This is a project that has been shaped by – and, we hope, will very much contribute to – the city around it in the years ahead.
Jo Bacon, partner, Allies and Morrison

My team's role on 100 Bishopsgate commenced nearly 12 years ago in a market not dissimilar to the post-pandemic economy that exists today. We were initially asked to interrogate the existing consent that was conceived before the Global Financial Crash of 2008 and propose changes to improve the building's viability and tenant attractiveness.

Our initial studies identified opportunities to increase the nett internal area by almost 15 per cent through a series of initiatives that elevated the efficiency and floor plate appeal. We similarly developed proposals to optimise the design of the façades and simplify the configuration of the central slip-form core and vertical transport.

We have since had the pleasure of collaborating with Allies and Morrison in a partnership developing the design and delivering the project over the past decade.

As in 2010, the market for tall office buildings may seem challenging, given the uncertainty around future demand. However, I am confident that the demand for buildings with 'good bones' that can be adapted to shifting tenant demands will endure and prosper. We were privileged to be able to work from a consented scheme that established a strong urban narrative.  Tall buildings that in this way positively contribute to the life and vitality of the city, are beautifully detailed as well as being highly efficient, flexible and optimised in terms of material use and energy consumption, will in our view endure and, in time, contribute to the vibrant palimpsest of the city.

Earle Arney, founder and CEO, Arney Fender Katsalidis

Client's view

The 100 Bishopsgate scheme is a modern, premier office, which places tenants' requirements at the heart of design, build and management considerations. The building's success, as evidenced by the record pre-let and subsequent occupation, is testament to the close collaboration between Brookfield Properties, Allies and Morrison and Arney Fender Katsalidis to create an appealing, fit-for-purpose and future-proofed workspace.

Throughout the pandemic, Brookfield's commercial properties, including offices, have remained largely open, to enable tenants to maintain critical infrastructure and operations. Our primary focus is currently on helping our tenants implement back-to-operations best practices – and on communicating the steps we are taking to make our office properties safe for workers to return to. In London, we expect to see continued demand for premium, well-located, office space with the best systems, technology and sustainability credentials. Buildings such as 100 Bishopsgate will be well-equipped to provide an environment that harnesses the power of in-person connections, along with added support for employees' wellness.

Dan Scanlon, senior vice-president, Brookfield Properties

Sustainability strategy

Though beginning over a decade ago, 100 Bishopsgate was ahead of its time, with a sustainability philosophy to do as much as possible using as few resources as possible.

A low-energy strategy was employed across the project, and includes a façade designed to achieve a high level of thermal performance while optimising natural daylight and incorporating a number of low and zero-carbon technologies. The building envelope was manufactured off-site, and the washrooms are also modular, with the internal fit-out prefabricated off-site.

The services were designed to be adaptable to changing tenant requirements. Environmentally conscious systems and materials were included in the building's design to maximise sustainability and reduce the carbon footprint over the lifetime of the building. Together, advanced building systems, efficient light fittings, zoning and automated controls result in a 24 per cent improvement over traditional construction methods, and are estimated to save over 600 tonnes of carbon a year. The building runs on a renewable electricity tariff and has efficient installations, such as LED lighting.

Efficient plumbing fixtures ensure water efficiency, resulting in estimated savings of 9.2 million gallons a year, compared with traditional fixtures. Additionally, sustainable drainage systems and the provision of attenuation tanks ensure the building has a neutral impact on surface water run-off. The waste water recycling unit recycles effluent water from the cooling towers, returning it to the system at equal or better quality than the incoming mains water supply. Such savings contribute significantly to the building's environmental IPPC assessment and BREEAM rating.

A green wall has been installed on the building's exterior to encourage pollinators and nesting birds. A rooftop garden on the podium provides both amenity for occupiers and introduces more biodiversity into the City.

Graeme Rapley, director, Arney Fender Katsalidis

Working detail

The façades of 100 Bishopsgate reflect the conceptual thinking behind the massing of the building and its rotational geometry – shifting from a parallelogram at the lower levels to a rectilinear form at the upper. The resulting fold line is thus an essential feature of the north and south elevations and is aided by the smooth crystalline glass façades employed. The fold line facilitates and expresses the geometric shift up until level 22.

The façade is constructed from unitised curtain walling with a subordinate anodised aluminium backing layer to frame and support the glass. The spandrel area features an oversailing glass sheet, which creates a thinner reading of the metal back-layer and helps to disguise the jointing between panels.

Another feature of the envelope is visual contrast. The predominantly glazed façades of the north and south are quite different from the more metallic east and west façades. This helps to soften the massing of the building and aids the reading of the geometric rotation as perceived from different points. These façades comprise anodised aluminium projections to create a filigree, which provides both solar shading internally and a richness in the visual character externally.

This metal veil is spaced off the façade to allow light to flood down its face, helping to create a separation between the mass of the building and the façade metalwork. The unitised panels are arranged so that the metal veil is formed from a series of C-shaped projections, which always read from left to right and create a grain that gives a direction to the elevation. This reinforces and aids understanding of the building's shifting geometry and sense of rotation.

The corners have an oversailing 'bird's mouth' arrangement that is treated differently, depending on which geometry it is helping to resolve. On the north-west and south-east corners, the geometry of the building gives a single vertical line and here the corner is treated with a solid metal oversail that projects from the incoming north or south façade. There is a recessed shadow gap to the respective east or west elevations in smooth, continuous vertical glazing, which aids the transition between glass and metallic façades. On the south-west and north-east corners, the geometry follows the fold line, to form an inclined edge that transitions to a vertical line at level 22, where the geometry resolves itself. The corners here feature an oversailing metal frame which projects from the north or south elevation, following the façade's edge as it transitions from an inclined to vertical surface. Here, the projecting oversail is an open frame and again, a recessed glass shadow gap aids the transition between the metal and glass facade types. It gives a lightness of appearance to differentiate it from the solid vertical corners.

Mark Foster, director, Allies and Morrison

Project data

Start on site 2011 (revised consent and demolition); 2015 (main works)
Completion 2019 (practical completion); 2020 (first tenant completion)
Gross internal floor area 127,000m²
Form of contract Design and Build (with Mulitplex Construction Europe)
Construction cost £430 million
Architect Allies and Morrison with Arney Fender Katsalidis
Client Brookfield Properties
Structural engineer Robert Bird Group
M&E consultant Hilson Moran
Quantity surveyor AECOM
Landscape consultant HED
Acoustic consultant Acoustic Logic
Other consultants Arup
Project manager Gardiner & Theobald
CDM co-ordinator Multiplex Construction Europe
Approved building inspector City of London District Surveyor's Office
Main contractor Multiplex Construction Europe
CAD software used Revit

Performance data

On-site energy generation From PV and solar: 1%
Airtightness at 50Pa 5.69m³/h.m²
Heating and hot water load 11.85 kWh/m²/yr
Overall area-weighted U-values
     wall: 0.46 W/m²K
     floor: 0.64 W/m²K
     roof: 1.01 W/m²K
     windows: 1.58 W/m²K

Annual CO2 emissions 19.5 kgCO2eq/m² (EPC)

Source: Architects Journal 

 
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