Deeper learning: Hall McKnight transforms disused basement for King’s College London

After several years of work by Westminster Council, the pedestrianisation of part of the Strand was completed at the end of last year. A once traffic-choked and polluted road has turned into a quiet space for walking and sitting. The 1717 church of St Mary-le-Strand, having spent most of its life as a traffic island, is now surrounded by planting, trees and benches, while the narrow pavement outside Somerset House has become a wide plaza.

The Strand’s name comes from its meaning as a shore, it being the shallower north bank of a wider River Thames before the Victoria Embankment was built. It is home to both King’s College London (KCL) and the adjacent Somerset House, for which the newly pedestrianised Strand creates a threshold space.

Since 2010, the campus has expanded rapidly to incorporate other existing buildings in the area, such as the east wing of Somerset House (a deal that took over 180 years to negotiate!) and the Aldwych Quarter site including the grand Bush House, formerly home to the BBC World Service.

Contained between the Grade I-listed King’s Building (the university’s founding building) and Somerset House – both designed by British Museum architect Robert Smirke in the mid-1800s – is a courtyard, beneath which, almost hidden, is the newly refurbished quad building for KCL’s department of engineering.

It’s an unusual project to say the least, bringing a very constrained ‘underground’ space back into use for the university, a space situated entirely within a Grade I-listed site in the Strand Conservation Area of Westminster.

Nearly 12 years ago, Belfast-based Hall McKnight was originally commissioned to design a much larger project at KCL. The £50 million scheme, which included a new tower, won approval in 2015 but involved highly contentious plans to demolish five historical buildings, designated as ‘unlisted of merit’. Objectors, including SAVE Britain’s Heritage, the Victorian Society, the Ancient Monument Society, the Courtauld Institute and Somerset House Trust, said the scheme would ‘erode a significant element of glory from neighbouring Somerset House’ and raised concerns about its potential effect on views, including from its famous Fountain Court.

In response to this ‘groundswell of opinion’, the scheme was called in by the secretary of state. But before a public inquiry could be held, the university withdrew the already approved plans, and decided to consider alternative options for the architecturally significant environment.

In 2017, Hall McKnight returned with a new scheme for the refurbishment of the 1950s Quad Building and improvements to the courtyard above – essentially a scaled-down version of what it had designed previously to improve teaching spaces. The project had become more public realm-focused with the addition of a series of quieter, but complementary interventions, which associate architect Emma Smart describes as ‘knitting together’ the existing constraints.

Standing at the northern edge of the Quad, the only indication that there is a building beneath is one circular oculus at its centre. Its shape, and that of the helical stair beneath, are nods to the helix of DNA, the discovery of which was made possible by scientist Rosalind Franklin’s work at King’s in the 50s in the very building below.

This is clearly not a statement project where one can judge the book by its cover, instead its interest lies in its technical and logistical achievements beneath the Quad.

Unlike Somerset House’s quads, this one is not entirely open to the public. It is entered through the 1971 Brutalist-style Strand Building via security gates. The southern end is semi-open to the embankment but, at present, it doesn’t provide straightforward access to non-KCL visitors. This is in contrast to the Strand side whose pedestrianisation ‘came into force’ part way through design briefing. It is, nevertheless, a key space for the institution, providing access to four buildings including the King’s Building, refurbished in 2006 by BDP, and the East Wing.

Hall McKnight’s scheme has aimed to re-establish a ‘lost axis’ of architect William Chambers’ original masterplan for the site, while also thermally upgrading the ground surface, which doubles up as a roof – an exceptionally demanding technical task given the need to maintain existing levels.

The post-war sloping structural deck was very fragile, meaning that heavy finishes couldn’t be placed on top to transform the space. A grid has been introduced to break up the ground plane and bring back some of the symmetry from the original masterplan, which once included a symmetrical wing of Somerset House that was never built. The grid – of flush metal inlays – ‘elevates the gravel’, says Smart. The proportions of the existing windows helped generate those of this grid on the ground in an attempt to ‘re-establish some order to the space’. It's very subtle but smart, tying together the existing patchwork context. Power and water outlets have been installed to facilitate outdoor events in summer months – useful for a central London university without a lot of external amenity space.

Either side of the quad, running east and west, are two lightwells, the western one open to the elements. Due to the quad’s slope and the levels around and below, the deck had to be insulated beneath. To enable this, the stone balustrade of the King’s Building had to be removed first to allow for waterproofing to be laid underneath.

On paper, the scheme isn’t the easiest to understand. To enter the two-storey, below-ground building, you first have to go through King’s Building – to the left of the Quad when facing the embankment. Just past the grand entrance (including marble statues of Sappho and Sophocles) and down an unassuming staircase, you are presented with a brick-arched thoroughfare, previously a storeroom. This now doubles up as a breakout space with new furnishings and the existing brick whitewashed, it being one of the few spaces in the engineering building not naturally lit. Amazingly, the decision to move the storeroom was made very late in the project. Previously, the plan had been to enter the  department  through a tiny side-corridor. The former store provides a sensitive transfer from the grandeur of the Grade I-listed King’s Building to the more contemporary subterranean building.

From here, the department’s layout is actually very simple. Long in shape, it reflects the footprint of the quad above. A helical concrete stair, lit by the oculus above, sits at the centre, acting as a hinge for the two mirrored sides – perhaps the project’s biggest example of Hall McKnight’s architectural flair for playing with bold forms and light.

Either side of this on each floor are two large teaching rooms. Although unusually long for lecture rooms, they have been flexibly designed with an AV system running along one edge and the opportunity for subdivision for smaller teaching groups. They are naturally lit by a long lightwell-cum-access route to the embankment. This can also be used for outdoor experiments, its ground surface due to be improved in the next stage of works.

Beneath the lightwell along the King’s Building side are ‘makers spaces’ for creating prototypes, their long footprints limited again by the dimensions of the existing. Large windows flank both of these, as well as the labs, allowing natural light to flow through and create that sense of transparency so desired in institutional design nowadays. The lighting has been sensibly calibrated to ensure that most spaces feel daylit. The temperature and lighting, generated from a centralised campus energy supply, are both carefully controlled to mimic outside conditions in an effort to minimise the feeling of having been in a basement even after hours of studying.

The existing and unused quad building was constructed in the 1950s following severe bomb damage in the war, and was previously fairly cellular in layout. It had been in a bad state for some time and had a leaky roof so the logistics of retrofitting it were complicated. Some of the original arches incorporated during its construction have been lost in the new scheme but others have been re-revealed. Not much digging was required to open up the spaces but additional pile foundations were put in because of the river’s proximity. The building’s façade to the western edge has also been refurbished to upgrade thermal performance and improve daylight, with new windows and frames added where required.

Internally, ‘it’s generally about robust finishes,’ says Smart. The school – which encourages the teaching of sustainability-focused engineering – has its students working on projects ranging from bamboo bikes to submarines for picking rubbish off the sea bed. Conforming with this thinking, it wanted a space that was long-lasting and flexible but within the confines of the existing building.

‘From a university perspective this is about managing the building affordably,’ says King’s senior project manager Robert Staton. ‘They don’t want to change the spaces.’ He alludes to the amount of waste produced by institutions altering their estate to match specific needs of users. The project uses a palette of hard-wearing concrete, tiling and oak throughout. It’s neat and utilitarian, yet derived from the Grade I-listed context.

Logistics in terms of location and proximity to the river complicated the scheme, despite working with an existing space. All building materials had to come in from the embankment through a tunnel. A crane runway was installed along the length of the quad, allowing three cranes to be installed during works, all without interrupting teaching. Having exposed services within – fitting with the scheme's engineering philosophy – was particularly complex due to the deck being insulated beneath.

When asked what’s next for the campus, for which there were once much grander plans, Staton confirms that planning permission has been achieved for 152-158 Strand. Where previously this was to be flattened to make way for a new block, it will now be refurbished, upgraded and consolidated. Masterplan options for the remaining campus are still being deliberated to inform future development. It’s refreshing to hear that these are being carefully considered rather than the university leaping into carbon-expensive cul-de-sacs.

‘The utopia is to make the quad all open and a full student zone,’ says Staton, referencing what other central London universities, such as the London School of Economics and University College London, have achieved. ‘We want to “Kingsify” the area,’ he adds, mentioning the possibility of new signage and food trucks and working with Westminster Council so they can take advantage of the newly pedestrianised Strand and make the campus more of a destination.

In an era where university buildings are becoming more public (Grafton’s Kingston Town House being a case in point), it’s disappointing that KCL’s Strand campus does not yet offer a pedestrianised route through to the Embankment. Nevertheless, this is probably the most logical, sensitive and straight-to-the-point project Hall McKnight could have achieved (particularly given the project’s controversial history). They have persevered for sure.

‘It is exactly as we envisaged at Stage 4,’ says a friend and ex-Hall McKnight employee when I mention I am writing about this scheme. There are a few moves that bring architectural delight – such as the stair, arched threshold and engagement with the history of the buildings surrounding the quad – but other than that it sticks to its guns in being a well-engineered and exceptionally functional building. Indeed perhaps that’s what we should be taking delight in.

When other universities have made a number of  standout but carbon-heavy moves (LSE springs to mind), the careful consolidation of assets seen here with its long-term view and consideration of context and users, is the best way forward.

Architect’s view

The Quadrangle Project brings back into use a building that occupies a highly unusual and constrained site. The building is situated entirely within a Grade I-listed site located within the Strand Conservation Area, its roof forming the Quadrangle at the heart of the founding campus. These conditions required high-quality and thoughtful design.

The thermal upgrade was technically demanding, given the need to maintain existing levels at Quadrangle (roof) level. New interventions and extensions within the listed environment use a contemporary language derived from the heritage context. The design of the Quadrangle space re-establishes the ‘lost’ axis of the original plan for the site by William Chambers.

The thermal upgrade of the post-war superstructure reduced the impact of the construction period upon the live environment of the campus and maximised the use of the site.

No heating or cooling is generated within the project; it is designed to make efficient use of a centralised campus energy supply. The retrofit of Quadrangle will assist King’s in supporting the future upgrade of the energy centre to zero carbon. We expect post occupancy monitoring to demonstrate a 70 per cent reduction in the energy demand compared to the original building.

The flexible planning and services approach of the teaching and learning spaces anticipates long-term viability of changing use. Students are immersed in an educational environment where theory, learning, collaboration, practical experimentation and making are practised within a highly accessible and open environment at the heart of the historic campus.
Ian McKnight, partner, Hall McKnight

Client’s view

The King’s Building Quadrangle was a multi-faceted project. It was the rejuvenation of an existing building, bringing 3,000m² of prime central London real estate back into use to create a Department of Engineering teaching and research hub. It was also a rejuvenation of external amenity space for all of King’s staff and students at its historic Strand Campus.

Sustainability was an important consideration for this project, and retaining the existing structure, despite its constraints operationally, was a fundamental part of the sustainable approach.

Briefing was critical to the project’s success. The design team worked closely with the department to ensure the building constraints did not limit the suitability of the space for the intended activities while ensuring that accessibility and other ED&I considerations were incorporated.

As with any university building, operational readiness for start of semester was critical. Working in collaboration with internal estates and facilities stakeholders, the incoming department and the contractor delivering the scheme, we were able to successfully navigate the commissioning and handover process. This collaborative approach continues during the first 12 months of operation.
Robert Staton, senior project manager, King’s College London

Engineer’s view

On the face of it, the building appeared to be approaching the end of its usable life so a key challenge for us was to retain as much of the existing building as possible.

Damaged finishes were peeling away from the structure, signalling failing waterproofing on the deck. We took a look beneath the surface with a suite of investigations, using thermographic surveying to identify the affected areas and quantify the damage to the existing structure.

We found that while there was, indeed, corrosion to the concrete-encased steel frame and hollowpot slab, even in the worst affected regions the water ingress hadn’t resulted in significant loss of section and the structure still appeared robust and suitable for keeping.

Through detailed back-analysis, we also determined that the capacity of the structure was significantly above the proposed use. This resulted in being able to justify keeping the full extent of the Quadrangle structure, which allowed more budget to be focused on beautiful lightwell inserts, stair core and Quad deck to improve the quality of the space for future generations to enjoy.

Keeping the existing building has significant benefits besides saving on cost and carbon. Less demolition meant less dust and better air quality. The reduced vehicle movements cut down congestion on local infrastructure. But most importantly, minimising disruption to campus meant learning and teaching could carry on with fewer interruptions.
Billy Squire, associate director, Elliott Wood Partnership

Working detail

Integrating the servicing requirements for a flexible learning commons within a former archive store in the centre of the Grade I-listed King’s Building vaults involved considerable co-ordination between the architectural, structural, services and joinery teams. The design intent was to ensure that ventilation provision, acoustic absorption requirements, lighting and electrical power provision were carefully integrated into a simple joinery element, allowing the brick-vaulted structure to be clearly read and celebrated.

All new interventions were set below the datum at the springing point of the brick vaults, including ‘hold-open’ doors which are integrated into the joinery and provide connection between the main King’s building corridor and the Quadrangle building.

Lintels supporting the openings in the existing brickwork align with the head of the service wall. The stained oak that forms the framing for the service wall matches the joinery used within the main Quadrangle fit-out. Lime-washing of the existing brickwork improves the visual comfort within the artificially lit environment.

Low velocity fresh air is supplied through a slot at the base of the service wall and then extracted through concealed grilles on the horizontal surface at the top of the wall. Uplights are concealed above the precast lintels and at the top of the service wall to reflect light off the lime-washed brickwork.

Throughout the project, a hardwearing base has been introduced (though coloured MDF is used in the teaching and learning spaces). Within the vaults a stainless-steel removable panel allows for chairs and tables to be placed against the wall and conceals the servicing behind. Above this, the space is softened by panels of fabric-covered acoustic absorptive material.
Emma Smart, associate, Hall McKnight

Project data

Start on site  October 2019 (shell and core), September 2021 (fit-out)
Completion  September 2022
Gross internal floor area  3,280m² (internal building), plus 2,000m² (deck)
Construction cost  £28.1 million (includes all phases of construction and external deck)
Construction cost per m²  £5,325 (including external quadrangle deck and internal area)
Architect Hall McKnight
Client  King’s College London
Executive architect  Rock Townsend (shell and core), Hall McKnight (fit-out)
Structural engineer  Elliott Wood Partnership (main design and appointed by shell and core contractor), Plan B (appointed by fit-out contractor)
MEP consultant  AECOM
Cost consultant  Turner and Townsend
Project manager  3PM
Principal designer  Hasco Europe
Approved building inspector  Sweco
Main contractor Farrans Construction (shell and core), Overbury (fit-out)
CAD software used AutoCAD, Revit
Annual CO2 emissions 25 kgCO2/m² (estimated)
Lighting designer Light Bureau
Planning consultant Gerald Eve
Heritage consultant Montagu Evans
Acoustic consultant AECOM (design stage), Hann Tucker (fit-out construction stage)
Electrical subcontractor D W Berryman
MEP subcontractor Envirotech Services
Internal joinery Crompton Joinery

Sustainability data

Percentage of floor area with daylight factor >2% Not calculated (limited access to daylight due to being in two storey basement structure. Daylight maximised through rooflights and replacement windows)
Percentage of floor area with daylight factor >5% Not calculated
On-site energy generation N/A (connected to KCL Strand Campus Energy Centre on a separate site)
Heating and hot water load  Awaiting figures following post-completion monitoring
Total energy load  Awaiting figures following post-completion monitoring
Carbon emissions (all) 25 kgCO2/m²/yr
Airtightness at 50Pa  Not supplied
Overall thermal bridging heat transfer coefficient (Y-value) Not supplied
Area weighted U-values
New build inserts, large lightwell structures: 0.71 W/m²K
New build inserts, small WC lightwell structures: 0.62 W/m²K
Wall to SHEW lightwell (existing external wall upgraded): 0.59 W/m²K
Replacement windows: 0.84 W/m²K
Existing roof/Quad deck upgraded: 0.17 W/m²K
Embodied / whole-life carbon 180 kgCO2eq/m²
Predicted design life in years 50 (shell and core)