St Andrew Square sits in the heart of Edinburgh’s ‘New Town’ World Heritage Site, at the eastern end of George Street, and a counterpoint to Charlotte Square at the west end. But unlike Charlotte Square, which is a virtually intact set-piece of Georgian architecture, St Andrew Square provides a more heterogeneous context with a wide range of Victorian, mid-20th century and early 21st century buildings. In many ways, then, a more permissive context than much of the World Heritage Site but, importantly, also one with little consistency in materials, height, massing, architectural language or street-level conditions.
Hoskins Architects and CDA investigated options for the redevelopment of a majority of the southern edge of the square, consisting of a handful of buildings – numbers 3 to 8 – of varying periods and quality.
The buildings had been interconnected as a company headquarters, extended and altered over a number of years, leaving a piecemeal, ad hoc assemblage of spaces when vacated. Initial studies from 2007, proposing retention of a number of existing buildings, proved to be commercially unfeasible and, following a change of ownership in 2013, designs were revised to incorporate further demolition. The final scheme comprises 9,300m2 ‘Grade A’ office space, 6,500m2 leisure/retail and a suite of luxury apartments.
OPEN AND SOLID
The massing strategy of projections and recesses reflects the scale of the historic plots on this side of the square, reconciling a historic grain with the contemporary demands of large-floorplate, open-plan office accommodation. The pursuit of an architecture that reveals and conceals as pedestrians move in relation to it was important to us, as was moving beyond the ‘dumb glass box’ of speculative office development. A series of metal and stone fins enables the complex to be very ‘open’ when viewed directly (taking advantage of extraordinary long views and maximising daylight), whilst appearing solid in oblique pedestrian views (in keeping with its Georgian and Victorian sandstone neighbours).
BRUSHED COPPER ALLOY
For the fins, Hoskins Architects and CDA appraised various metals and identified a group of copper alloys for long-term quality and handsome weathering. Finally, they settled on a golden alloy of copper with aluminium and zinc, giving a rich golden through-colour that is very stable. Unlike bronze or brass, this alloy’s surface retains its golden colour and gradually loses some of its sheen as the oxide layer thickens with exposure to the atmosphere, resulting in a protective matt finish.
However, the architects wanted a much quicker transition – from the initially reflective golden surface to a relatively matt golden hue – than happens naturally in the environment. This was achieved with bespoke surface treatment of the copper alloy in the factory using a belt sander. Various grades of grit were tested until a non-reflective, brushed surface was produced. The brushed copper alloy will now change in more subtle ways over time.