Alex Fell of Howells explores the proposals for 10 Cabot Square, where retaining and adapting the existing structure would improve daylight, create outdoor amenities and enhance energy performance. 

Every retrofit project requires a unique approach informed by the characteristics of the existing building. At Howells, we leverage maximum value from every intervention we make, enhancing inherent qualities and addressing shortcomings. Whilst in some instances this means a light-touch approach to retrofit, other buildings warrant more radical reimagining. 

10 Cabot Square is an office building located in the heart of Canary Wharf and constructed during the early 1990s in the decorative post-modern style of the district’s original masterplan. 

Whilst the building’s structure remains robust, there are several architectural challenges which impact its appeal to tenants seeking high-performance and amenity-rich offices. The large footprint and unlit internal atrium result in poor levels of natural daylighting and deep floorplates, a challenge exacerbated by the proportions of the existing window openings. The existing pre-cast façade and glazing units are failing, and the building does not offer any external amenity space. 

The building is therefore an ideal candidate for adaptive retrofit: despite its architectural shortcomings, the steel frame and piled foundations are in good condition and have excess structural capacity, while stair and lift provisions are appropriate for modern occupancy levels. 

Our proposals balance an optimised re-use of the existing structure with meeting the demands of modern tenants through a three-part strategy to re-use, adapt and enhance the existing building.  

1. Re-use 

The project’s circularity and whole-life carbon have informed the development of the proposals from the outset. Demolition is minimised with 100% of the existing foundations and over 70% of the superstructure retained. Howells estimates that 350 kgCO2e/m2 (28,000 tonnes of CO2e) are saved compared to an equivalent new build. In collaboration with Material Index, an audit of the existing building has been undertaken to maximise opportunities to re-use salvaged materials.  

2. Adapt 

The existing structure has been adapted by cutting back the deep floorplates at upper levels to improve internal daylighting and form external amenity terraces. The existing atrium has been extended down to ground floor and outwards to the north and south facades, drawing daylight into the centre of the building. 

The excess structural capacity in the existing building is leveraged to enable the addition of two new office floors, recouping area lost through reducing floor plate depths and creating external terraces to deliver over 600,000 sqft of net office space.  

3. Enhance 

The adaptation of the existing structure is enhanced by new amenity space ranging from outdoor terraces and atrium breakout spaces to end of trip facilities which support active travel. A curated landscape design for the external terraces delivers biodiversity uplift and provides access to nature, outdoor space and views. 

The design supports a long-life, loose-fit approach to adaptability by delivering flexible and futureproofed office space. Floor plates, cores and servicing zones are designed to support multiple different tenancy splits and office layout typologies, enabling easy adaptation to different modes of working. The extended internal atrium facilitates a visual connection between ground floor and office levels above and is activated by informal breakout and amenity spaces. 

The proposed façade gives 10 Cabot Square a new visual identity, with high-performance ‘ribbon’ windows which maximise internal daylighting whilst optimising thermal performance through a balance of solid and glazed façade area. Projecting cills above the windows mitigate solar gain through passive shading in summer, whilst allowing passive solar heating in winter. These measures set the design on track to achieve NABERS 5.5* and BREEAM Outstanding accreditations. 

Howells’ proposals for 10 Cabot Square serve as an exemplar of commercial adaptive retrofit, transforming a vacant building which is no longer fit for purpose into a sustainable, adaptable and market-leading modern workplace. 

Retrofit works on 10 Cabot Square will commence once planning and a pre-let is secured.