→ Sustainable deep retrofit of 1990s office building
→ Carbon footprint analysis showed refurbishment as most low carbon option

Gresham St Pauls is the sustainable deep retrofit of 1990s office building in the City of London, retaining core structure and walls, with the two upper stories rebuilt and an extra story added. It will be an exemplar of low carbon refurbishment and prolonging building life, saving embodied carbon while upgrading services and glazing to modern efficiency standards.

The refurbishment offers a significant increase in the net lettable area of the building. The atria and corners at levels five, six and seven are infilled, levels eight and nine are remodelled and an additional 10th floor is added to increase capacity. The building is positioned and sold in the market ‘as new’ despite the primary structure and majority of the envelope being retained.

The ground level is activated with a new entry experience and retail space. New amenities include extensive facilities for cyclists and an improved contemporary architectural appearance. At the upper levels, setbacks and flat roofed areas are landscaped, with extensive views of St Paul’s and the City of London. 

A carbon footprint analysis of July 2020 undertaken by WilkinsonEyre for Stanhope calculated that the refurbishment option will, assuming a sixty year lifespan, result in the lowest amount of carbon generated in building and operation. Whereas a new building would significantly increase the amount of emissions generated by development on site, when emissions are considered per unit of gross floor area (kgCO2e/m2) in line with the industry best-practice, retention and refurbishment outperforms both the ‘do nothing’ and ‘demolition and rebuilding’ options over the projected lifecycle. This makes refurbishment the best performing most carbon-efficient option.