Sheppard Robson plan to re-position Calton Square in Edinburgh

Image: CGI of interior of Calton Square re-positioning - Retaining 88% of the existing structural frame, the major refurbishment seeks to create a new identity for the building, through reconfiguration and enhancements, that exemplifies sustainable and wellness-centred design (Courtesy Sheppard Robson)

Sheppard Robson has submitted plans for the significant repositioning of Calton Square, a landmark office building in Edinburgh’s city centre. Development manager Ardstone Capital Ltd (UK), acting on behalf of the owners advisor Macquarie Asset Management, has coordinated the project to extend the building from 150,000sq ft to 200,000sq ft with a series of significant design changes which will align the building to the demands of the modern occupier and provide a significant uplift in the environmental performance of the building.

The design process began with forensic analysis to assess retention options and select the best fabric-first reuse strategy. This drive to reuse as much as possible, on and off site, was balanced by addressing its sensitive context within its extraordinary location in Edinburgh’s New Town – adjacent to Calton Hill, a UNESCO World Heritage Site.

Originally completed in 1998, the existing building presented several urban challenges and was unsuited for both the modern occupier and for responding to current climate challenges. Currently, large areas of glazing result in overheating and operational inefficiencies. Other considerations included improving the fragmented internal layout, replanning the cores, and upgrading the entrance experience characterised by the site’s varying street levels and associated stepped primary access.

The main entrance has been significantly extended to provide step-free access and a welcoming arrival experience. The double-height space transforms the Leith Street frontage with expansive glazing, improving transparency and connectivity with the public realm. The new reception comprises a range of co-working, lounge and café spaces creating an energetic and dynamic quality on arrival. This leads through to the heart of the project – a dramatic triple-height atrium covered with a new structural timber roof that repurposes an underutilised internal courtyard. This central space provides an opportunity to accommodate cultural uses benefitting the local community through social value.

Sheppard Robson's design creates a cohesive envelope which harmonises with the historic surroundings of Calton Hill. The new design, with its base, middle and top, echoes the traditional Edinburgh Feu, broken up into vertical bays to reflect the grain of the local tenement blocks. The sandstone façades further root the building into the context, with accents of green referencing Calton Hill.

Environmental modelling has driven the design of the high-performance façades, which introduce profiled spandrels and vertical fins to maximise self-shading and improve thermal performance.

Occupier terraces are located across levels five to eight with a large communal green space on the uppermost level. The roof accommodates biodiversity through its wildlife planting and brown habitat and PV panels are integrated within the greenery. This ‘green crown’ of biodiverse terraces and the sawtooth profile of the top floor provides a sensitive design response to the Edinburgh skyline and views from Calton Hill back to the city centre.

The holistic sustainability and wellness strategy employed on the building targets BREEAM ‘Outstanding’, NABERS 5* and WELL Platinum.

Mark Kowal, Partner at Sheppard Robson, commented: “Calton Square is a thoughtful blend of old and new. Our design approach has been to integrate the building into its unique location, creating a seamless transition between the city's Old and New Towns. The goal is to reposition the existing building by creating an exemplary adaptive reuse project that excels in environmental performance and becomes an asset to the community.”

Image below: courtesy of Sheppard Robson