Powering up

The largest single-occupier development in Glasgow for around 25 years has made use of a bespoke curtain wall system by Kawneer.

The architectural aluminium supplier’s system features left and right-handed mullions and split transoms to cater for the high movement in the 14-storey new flagship headquarters for Scottish Power.

The 20,000m2 building, on a formerly vacant site on the corner of St Vincent Street and India Street that was once the base of the old Strathclyde Regional Council, accommodates almost 1,900 Scottish Power staff and replaces its former HQ in the city’s South Side and offices in Falkirk.

Other elements by Kawneer include AA720 doors, which were developed to meet the latest European requirements for thermal performance, and second-floor and sixth-floor internal rooflights.

The Kawneer elements on the £72 million building were installed between vertical concrete panels by approved Edinburgh-based Charles Henshaw and Sons who worked alongside Page Park Architects.

It had become apparent that a standard SSG (structurally silicone glazed) curtain wall system was not going to meet the exacting criteria. Considerable live load movement was inherent in the building design, and in some places concrete slabs would deflect by +/-12mm which was too great a margin for standard SSG to accommodate.

Kawneer’s technical team, therefore, devised the bespoke capped solution based on the manufacturer’s AA110 curtain wall with 65mm sightlines as opposed to the AA100 system with 50mm sightlines.

A gap between the specially designed transoms accommodates the +/-12mm deflection characteristic of the concrete floor slabs. This expansion joint is used on every two floors, with a straightforward butt joint deployed on each intermediate floor. Additionally, a large 40mm glazing rebate in the mullions allows the glazing to rack in the frame, allowing for sideways movement.

This was fully performance tested at the Vinci technology centre to meet the CWCT (Centre for Window and Cladding Technology) standard for Systemised Building Envelopes Test Sequence B.