A 10-storey, 25,000m² commercial office building, recognised as one of the City of London’s smartest and most sustainable workplaces.

BREEAM Outstanding
2024 British Construction Industry Awards Shortlist – Commercial Project of the Year

JJ Mack Building is a new 10-storey office building in Islington offering 20,000m² of office space with 5,000m² of retail and 900m² of external terraces. The steel frame incorporates transfer beams to create large internal floor plates, while a storey-height vierendeel truss allows a column-free entrance area.

The building’s facades have been articulated to distinguish between a ‘base’ building and an ‘upper’ building, corresponding to the massing where the building steps back from the street at the upper levels. These two elements are defined with natural Portuguese Moleanos limestone from street level and lightweight aluminium and full-height glazing at the top of the building. A unitised curtain wall approach was adopted throughout, with 3m-wide units providing large-format glazing at typical floors.

Eckersley O’Callaghan provided facade engineering services for the project, assisting in design development in RIBA Stages 3-4 and monitoring of the contractor’s design during RIBA Stage 5 to ensure alignment with the employer’s requirements. Among the complications was a fire-rated boundary condition with adjacent plots. The building is fully electric, making use of the nearby district energy network and rooftop photovoltaics. Energy use is therefore 50% lower than Part L regulations and achieves BREEAM Outstanding.

Location
London, UK

Client
Helical PLC | AshbyCapital

Architect
Lifschutz Davidson Sandilands