AJ Retrofit Awards 2021 winners revealed

The conversion of a warehouse in Hackney, east London, not only found a new use for a building that faced demolition but reused as many materials as possible – both from the site and reclamation yards.

The AJ’s Rob Wilson and Fran Williams, who chaired the various judging panels, said the winning project was  ‘notable for having transformed some previously unremarkable and ramshackle commercial structures into a rather poetic and beautiful whole’.

The scheme, which also won the Workplace under 2,000m² category, was revealed as the overall winner at the AJ Retrofit Awards virtual awards event held on Wednesday 24 February.

Among the other winners were Haworth Tompkins’ upgrade and extension of Kingston School of Art, Tonkin Liu’s conversion of a steel-frame water tower into a home and the refurbishment of Grade II*-listed Lincoln's Inn Great Hall and Library by MICA Architects.

The AJ Retrofit Awards programme is one of the most highly regarded in UK architecture and celebrates the design, engineering and construction excellence that prolongs and improves the life of our built world.

Retrofit of the Year

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Photos by Taran Wilkhu

Yorkton Workshops by Cassion Castle Architects with Pearson Lloyd (Winner: Workplace under 2,000m² category)

This conversion of a nondescript warehouse building in Hackney as a new home for a product design practice was praised by the judges as ‘proper retrofit’, particularly given that demolition was an option.

‘The architects had a bold approach here with real bravery shown through the mishmash of old and new,’ said one judge, also commending the scheme for being eminently ‘replicable’.

The premises consist of two blocks – one Victorian and one from the 1980s – containing workshops, studios, meeting and event spaces, linked by a new entrance and circulation element.

The retained external envelope, including the concrete floor slabs, was upgraded to modern standards of insulation and airtightness, with recycled materials used extensively – either set aside and reused from demolition or sourced from reclamation yards. ‘The honesty of the brickwork is beautiful,’ observed one judge.

Cassion Castle Architects acted as both architect and main contractor in a fluid design process in which they credit the client as ‘co-creator’ – a model of architect-client collaboration. RGW

Location Hackney, London • Client Pearson Lloyd • Main contractor Cassion Castle Architects • Engineer Structure Workshop • Services engineer Energy Test UK • Completion date September 2020 • Building occupation date September 2020 • Project cost Undisclosed • Overall embodied carbon 46.3tCO₂e • Embodied carbon 85.7kgCO₂/m² • Annual predicted carbon emissions 32kgCO₂/m²/year • Predicted reduction on existing emissions 43%

Cultural Buildings under £5 million

Photos by Simone Bossi

Surrey Docks Farm, London by PUP Architects

‘An impressively coherent scheme which reinvents the building’ is how the judges described the refurbishment, reinstatement and expansion of this city farm, a centre for education about the environment and responsible farming.

The rework of this small group of farm buildings came after extensive local consultation and was commended for its holistic approach to sustainability and reduction of its carbon footprint, from the specifying of materials, to choosing local suppliers and minimising construction waste. The result not only improves facilities and accessibility for its local users, but creates a flexibility of space which allows the farm to be used for commercial events, helping ensure its future financially. The project was particularly commended for the thoroughness of its design approach, exhibiting ‘a modesty and consistency in its material language and approach at all scales’. RGW

Location Surrey Docks, London • Client Surrey Docks Farm• Main contractor John Perkins Projects• Engineer Structure Workshop • Services engineer John Perkins Projects • Completion date January 2020 • Building occupation date January 2020 • Project cost £630,000 • Area weighted U-value for whole envelope (existing) 1.31W/m²K • Area weighted U-value for whole envelope (post-retrofit) 0.31W/m²K

Cultural Buildings £5 million and over

Photos by Phillip Vile

The Malthouse, the King’s School Canterbury by Tim Ronalds Architects

This conversion of a Victorian brewery maltings into a school theatre and drama centre was described by judges as combining ‘a freshness of approach while sensitively retaining the character of the existing building’.

They commended the repurposing of what had been a semi-derelict building for the way it preserved the building's qualities ‘tonally’ and yet created a very flexible, practical facility. The replacement of the windows, removing large modern insertions and restoring small openings to match the remaining original ones, was particularly noted as a simple but very successful move.

‘Architecturally  very satisfying and inventive’ was how one judge summed up the scheme. RGW

Location Canterbury • Client The King’s School, Canterbury • Main contractor Buxton Building Contractors • Engineer Price & Myers • Services engineer Skelly & Couch • Theatre consultant Charcoal Blue • Completion date April 2019 • Building occupation date April 2019 • Project cost £10.7 million
Annual predicted emissions 49.7kgCO2/m² • Area weighted U-value for whole envelope 1.06W/m²K

Health

Photos by Verity E. Mulligan

Ada Belfield Centre and Belper Library by Glancy Nicholls Architects

This community-focused scheme for Derbyshire County Council was commended by the judges for rising to the ‘challenge of reusing complicated old buildings and bringing them back into use’. It consists of the conversion of a 19th-century factory building into a residential care home combined with a new community library. The judges thought this could provide a great model for other local authorities, both in combining facilities and in repurposing semi-derelict buildings.

The care home has been designed in line with the Stirling University gold standard for dementia design principles, with the judges liking the double-height interiors in the library and how the new extension worked ‘sympathetically with the strong qualities of the existing buildings’. RGW

Location Derbyshire • Client Derbyshire County Council • Main contractor Robertson Construction • Services engineer Derbyshire County Council • Completion date May 2020 • Building occupation date July 2020 • Project cost Undisclosed

Higher and Further Education

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Photos by Philip Vile

Kingston School of Art by Haworth Tompkins

This highly complex upgrade and extension of Kingston University’s Knights Park Campus to provide creative space for its school of art was carefully managed over 13 phases to ensure the campus remained operational throughout.

The 1970s Mill Street Building’s existing brick, steel and concrete shell was reused, resulting in 1.5 million kg of embodied carbon being locked in compared with building new. The school has achieved a BREEAM Outstanding rating, partly due to the addition of ‘deep sculptural’ weathering-steel window surrounds and fins to the south elevation for solar shading. At roof level, 800m² of green roof has also been introduced to enhance biodiversity and attenuate rainwater runoff.

It’s not just carbon savings that have been made here though; improvements have conserved the building's worn-in character, successfully preserving its creative atmosphere. ‘This scheme embodies just what these awards are celebrating,’ agreed the judges. FW

Location Kingston Upon Thames • Client Kingston University • Main contractor Overbury • Principal designer PFB Construction Management Services • Engineer MLM • Services engineer CBG • Completion date November 2019 • Building occupation date November 2019 • Project cost £20 million • Annual energy consumption 126.18Wh/m² • Whole-life carbon 1,992kgCO₂e/m² • Annual carbon emissions 25.2kgCO₂/m² • Reduction in annual emissions 52%

Hotel, Retail and Leisure

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Photos by Tim Soar

The Standard, London by Orms, Shawn Hausman Design and Archer Humphryes Architects

This project transforms an unloved 1970s Brutalist council office in Euston into a hotel – a scheme the judges described as ‘remarkable’.

The building was originally designed by Camden Council’s in-house architects as an annexe to the town hall. Despite being identified as detracting from the character of the local conservation area, Orms and its client Crosstree Real Estate Partners worked to retain it, converting it into a 266-bed boutique hotel while retaining 94 per cent of the primary structure including basement and piling.

The judges particularly commended the new three-storey extension for responding to the existing – the addition clad in stainless steel, with columns threaded down through existing waffle slabs to the first-floor transfer slab. A reinstated public garden to the south reconnects the building to the local streetscape. FW

Location Euston, London • Client Crosstree Real Estate Partners • Main contractor McLaren • Engineer Heyne Tillett Steel • Services engineer Arup • Interior architect Archer Humphryes • Interior designer Shawn Hausman Design • Completion date June 2019 • Building occupation date September 2019 • Project cost Undisclosed • Annual energy consumption 126.18Wh/m² • Whole life carbon 305 kgCO₂e/m² • Area weighted U-value for whole envelope (existing) 0.47W/m²K • Area weighted U-value for whole envelope (new build) 0.52W/m²K

Highly commended

House under £250,000

Photos by David Grandorge

The Linney by Casswell Bank Architects

The judges praised this ‘wonderful’ scheme, which transformed a dilapidated 19th-century cow-barn into a new dwelling, as ‘highly accomplished’ particularly in its ‘beautiful and sensitive use of materials’.

The barn was originally designed for cows to enter from both sides through identical façades composed of three diminutive arches. The new design emphasises these features by constructing the new envelope within the thickness of the existing stone walls, which judges thought ‘made for a very thoughtful architectural intervention’.

Internally, a central wall has been removed creating a double-height living and cooking space. A timber platform has a series of smaller spaces and service areas arranged above and below it.

The project uses a lean palette of natural, breathable materials, including compressed wood insulation, local structural timber and lime plasters, impressing judges who called the scheme ‘a great articulation of retrofit principles’. RGW

Location Bratton Fleming, north Devon • Client Private • Main contractor Kevin Jenkinson Kitchens • Engineer Andrew Waring Associates • Services engineer Max Fordham • Completion date June 2019 • Building occupation date June 2019 • Project cost £140,000

House £250,000-£500,000

Photos by Jack Hobhouse

House-within-a-House by alma-nac

‘A really creative, replicable exemplar, done beautifully and with wit’ was how judges summed up this project. It saw an incongruous three-bedroomed 1950s house on a bomb site encased and expanded into a six-bedroom villa, akin to the original on the site, without resort to demolition.
This was possible in part due to the house having been empty for two years, so liable for only 5 per cent VAT, showing how a VAT reduction encourages retrofits.

The post-war structure was retained with a new timber frame structure piggy-backing off it, encased in a new highly insulated brick skin. By retaining and adapting the original structure, 12,670 bricks and 12.85m³ of concrete were saved from landfill with estimated annual CO₂ emissions reduced from 61.55kg/m² to 16.49kg/m².

The judges commended this scheme for being ‘a very polished submission’ with a thorough range of data provided, with one saying that they were ‘blown away by it’. RGW

Location Brockley, London • Client Private • Main contractor David Stewart Building Contractor • Services engineer Constant Structural Design • Completion date April 2019 • Building occupation date September 2018 • Project cost £495,000 • Annual carbon emissions (existing)  • 61.55 kgCO₂/m² • Annual carbon emissions (post-retrofit) 16.49 kgCO₂/m²

Highly commended

House over £500,000

Photos by Dennis Pedersen

The Water Tower by Tonkin Liu

This conversion of a steel-frame water tower and tank into a home was described by the judges as ‘gutsy and powerful’.

It was commended for being ‘really well executed’ with an impressively inventive use of cross-laminated timber (CLT), in particular the ‘stunning’ cantilevered CLT stair  which, by forming a compression spiral, stabilises the historic steel-frame structure.

The stair leads at the top level into a living room located in the rusty steel box of the original water tank, its window cut in as a continuous horizontal slot ‘like a ship’s bridge’.

Below the tank, the entire steel-frame structure is clad in light corrugated metal panels with CLT panel infills which form internal walls and finishes.

Judges called the scheme ‘dramatic and inventive’ and ‘dynamic and unique’, commending it as a ‘thoroughly engaging project’. RGW

Location Castle Acre, Norfolk • Client Private • Main contractor MNB Services • Engineer Rodrigues Associates • Services engineer Integration • Completion date February 2020 • Building occupation date February 2020 • Project cost £575,000 • Dwelling emission rate (DER) 9.68kgCO₂/m²/year

Housing

Photos by Andrew Lee

Woodside Multi-Storey Flats, Glasgow by Collective Architecture

‘A powerful and instructive model for retrofitting and recladding a tower block holistically’ was how the judges summed up this project, which saw the refurbishment of three multistorey blocks in a city that has seen almost a third of its tower blocks demolished in the last 15 years.

Aiming to mitigate fuel poverty for around 314 homes, the project was anchored in extensive consultation with residents, who remained in occupation for the duration of the works.

Open balconies were transformed into winter gardens while, at ground level, community rooms, children’s play areas and art-studios replaced redundant pram stores.

The retrofit targeted the Passivhaus EnerPHit standard and has resulted in a 70 per cent reduction in operational carbon emissions with post-occupancy evaluation planned to monitor environmental conditions and energy demand over the next five years.

‘Technically to be commended,’ said one judge, ‘especially as achieved on an impressively tight budget of just over £40,000 per flat.’ RGW

Location Woodside, Glasgow • Client Queens Cross Housing Association • Main contractor Engie Regeneration • Engineer Cundall • Project manager Faithful & Gould • Services engineer Building Services Design • Completion date October 2019 • Building occupation date October 2020 • Project cost £13 million • Annual CO2 emissions 28_kgCO₂/m² • Overall area-weighted U-value 0.36W/m²k

Listed Building under £10 million

Worcester Cathedral Undercroft Learning Centre by Acanthus Clews Architects

This project is about taking a space that was previously inaccessible and completely reactivating it. Worcester Cathedral’s undercroft was transformed into a learning centre for the cathedral’s education department – the first time that the 12th-century Grade I-listed former monastic refectory cellar and scheduled monument has been brought into public use.

Through extensive research, consultation and investigation into the existing fabric, the team was able to justify removing a section of less significant Victorian masonry to allow access into the space. Stone walls and vaults have been subtly repaired in line with the space’s original utilitarian service function and other interventions have been kept to a minimum.

A critical element of the project involved the replacement of the modern concrete slab with a level breathable limecrete underfloor heating system with a stone finish. The limecrete prevents moisture issues caused by reintroducing people into the space.

The judges praised the project’s clever simplicity and the way that changes made hadn’t affected the building’s character. ‘Although it appears that very little has been done, a lot has also been done, but carefully,’ they said. FW

Location Worcester • Client The Dean & Chapter of Worcester Cathedral, Worcester Cathedral • Main contractor Croft Construction • Engineer Andrew Waring Associates • Services engineer Chris Reading Associates • Completion date September 2019 • Building occupation date October 2019 • Project cost £1.5 million • Annual predicted energy consumption 277 kWh/m²/year

Highly commended

Listed Building £10 million and over

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Photos by Andy Stagg

Lincoln's Inn Great Hall and Library by MICA Architects

The Grade II*-listed Great Hall and Library refurbishment project is the culmination of MICA’s 2014 masterplan for the Lincoln’s Inn estate. Sensitive refurbishment and a series of interventions have significantly improved the building’s facilities. This includes excavating a large basement to create floor space for education and conferencing, and replacing an existing building with a more respectful extension to the library. The removal of 20th-century additions has revealed more of the Great Hall’s character, while reopening the southern entrance has returned a sense of ceremony to the space.

The judges commented on the extraordinary care and effort taken in repurposing this building and believed that the ‘balance has been rightly drawn’, adding: ‘This is a project about creating a sustainable future for a listed building that doesn’t detract from its spirit.’ FW

Location Lincoln’s Inn, London • Client The Honourable Society of Lincoln’s Inn • Main contractor John Graham Construction • Engineer Gardiner & Theobald • Services engineer Mott MacDonald • Completion date July 2019 • Building occupation date August 2019 • Project cost £25 million • Annual energy consumption (regulated) 32.66kWh/m²/year • Annual carbon emissions (regulated and unregulated) 16.2 kgCO₂e/m²

School

Photos by Jim Stephenson

Hackney School of Food by Surman Weston

This project, ‘a standout winner’ for the judges, is a joint venture between the Chefs in Schools charity and a federation of three Hackney primary schools. Sited at one of these, Mandeville Primary School, it consists of the conversion of a disused caretaker’s house into an educational kitchen for children and adults.

Around this, a previously underused part of the school grounds has been turned into productive gardens with outdoor cooking and eating spaces, providing a new community space for local residents to enjoy.

The judges praised the scheme for being ‘refreshingly simple and modest while not afraid to make brave, bold moves, such as removing a floor’ or using a spray-foam insulation under the roof, which is left exposed, minimising material use. It was also commended for ‘achieving an amazing amount on a tight budget’. It is, according to another judge, ‘a fantastic scheme full of a sense of fun and joy. This scheme not only reinvents the building but education too.’ RGW

Location Clapton, London • Client LEAP Federation, Mandeville Primary School • Main contractor Modernarc • Engineer Structure Workshop • Services engineer Peter Deer and Associates • Completion date February 2020 • Building occupation date February 2020 • Project cost £307,000 • Predicted annual CO2 emissions 14CO₂/m²/year • Predicted reduction in annual CO2 emissions 85%

Workplace under 2,000m²

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Photos by Taran Wilkhu

Yorkton Workshops by Cassion Castle Architects with Pearson Lloyd

This conversion of a nondescript warehouse building in Hackney as a new home for a product design practice was praised by the judges as ‘proper retrofit’, particularly given that demolition was an option.

‘The architects had a bold approach here with real bravery shown through the mishmash of old and new,’ said one judge, also commending the scheme for being eminently ‘replicable’.

The premises consist of two blocks – one Victorian and one from the 1980s – containing workshops, studios, meeting and event spaces, linked by a new entrance and circulation element.

The retained external envelope, including the concrete floor slabs, was upgraded to modern standards of insulation and airtightness, with recycled materials used extensively – either set aside and reused from demolition or sourced from reclamation yards. ‘The honesty of the brickwork is beautiful,’ observed one judge.

Cassion Castle Architects acted as both architect and main contractor in a fluid design process in which they credit the client as ‘co-creator’ – a model of architect-client collaboration. RGW

Location Hackney, London • Client Pearson Lloyd  • Main contractor Cassion Castle Architects • Engineer Structure Workshop • Services engineer Energy Test UK • Completion date September 2020 • Building occupation date September 2020 • Project cost Undisclosed • Overall embodied carbon 46.3tCO₂e • Embodied carbon 85.7kgCO₂/m² • Annual predicted carbon emissions 32kgCO₂/m²/year • Predicted reduction on existing emissions 43%

Highly commended

Workplace 2,000 to 10,000m²

Photos by Will Pryce

Wellington House by MATT Architecture

Judges praised the ‘unbelievable transformation’ achieved by this retrofit of a town-centre office block, which nearly doubled its lettable space while retaining 80 per cent of its existing structural frame.

This frame is overlaid with a new ceramic tile façade, made using a combination of digital and traditional hand-finishing techniques, which draws on the site’s history to fit with its conservation area context.

It incorporates features such as photovoltaic panels and a green roof, while inside, a displacement ventilation system uses the floor voids as a supply plenum for the fresh air that is extracted through the cores, massively reducing ducting and mechanical kit.

The project’s success is reflected in the building being let for more than double its pre-refurbishment rent. It was also praised for how it incorporated ‘great community engagement and feedback’. As one judge summed up: ‘This is retrofit for the long term’. RGW

Location Wimbledon • Client Columbia Threadneedle Investments • Main contractor ISG • Engineer Tuffin Ferraby Taylor • Services engineer Cundall • Completion date June 2019 • Building occupation date March 2020 • Project cost £12.2 million • Annual predicted carbon emissions 16.5kgCO₂/m²/year

Workplace over 10,000m²

Photos by Tim Soar

160 Old Street by Orms

A project that ‘truly embraced retrofit’, according to the judges, saw the rework of a 1970s former Royal Mail building into a contemporary office with 14,200m² of workspace over 11 floors. This includes two new additional storeys as well as the conversion of a basement car park into workspace. Four new retail units on Old Street were also part of the scheme.

Efficient new plant and services were combined with enhanced insulation and façade treatments. The judges commented on the ‘great glazing ratios’ and how ‘the structure was reused creatively.’ Other features include blue roofs for rainwater attenuation, roof-mounted photovoltaic panels, a variety of sedum and wild flower roofs, bug hotels and bird boxes.

Together this has delivered a carbon footprint of 205kgCO₂/m² for the finished structure, which is less than the RIBA 2030 carbon zero benchmark target of 250kgCO₂/m². RGW

Location Old Street, London • Client The Great Ropemaker Partnership (joint venture between Great Portland Estates and Ropemaker Properties)  • Main contractor Wates • Engineer Heyne Tillett Steel • Services engineer Hilson Moran • Completion date January 2020 • Building occupation date February 2019 • Project cost Undisclosed • Total carbon footprint 205 kgCO₂/m²

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