In the southern part of the new extension, structural steel links onto the original overhanging steel beams give a 1m band of glazing between the new extension and the existing structure. The overhead glazing allows natural light into the informal seating area below. The new design was required to show innovation, creativity and technical excellence. The main project objective was to create a world-class environment for employees and visitors, combined with an energy efficient, sustainable design. To achieve this, the project team took a hierarchical approach. First, the building form was optimised so that, by considering building massing, orientation, and envelope performance, it was possible to enable a highly energy-efficient building. Only once the building performance was optimised were the specific low energy systems selected.


SCOTSTOUN HOUSE FACTFILE


Arup first began to practise in Edinburgh in 1960. The late Peter Foggo, of Arup Associates, was commissioned to design a new purpose-built office for Arup in South Queensferry, 8km west of Edinburgh. This original building, designed in 1964/65, was a very elegant single storey pavilion building, set within the walled garden of a previously demolished country house in the grounds of a 2.43ha estate.


The modernist principles of ‘light and air’ were key aspects of the original design, maximising natural daylighting and natural ventilation, as well as creating a visual link between the office areas and the surrounding landscape and gardens. The main purpose of these modernist design principles was to create a building that would allow for occupants to work in an environment with a strong sense of health and wellbeing. Foggo formed Foggo Associates in 1989, going on to design the first four phases of Broadgate in London and 123 Buckingham Palace Road, the commercial offices adjacent to Victoria station.


34 CIBSE Journal February 2013


original space, converting the open courtyard, which it formerly enclosed for more offices, and extending along the eastern boundary of the walled garden that lies to the north. This east-facing new-build component


houses a new main entrance and reception area, meeting rooms, toilets, print room and staff area. The original stable blocks to the north beyond the walled garden were converted into mechanical and electrical plant space, facilities for staff showers, an independent remote conference room and a new cycle shed to store up to 20 bicycles.


The structure The original building comprised timber joists, boarding and roofing felt, all supported on steel universal beams spanning between precast concrete wall units. The roof overhangs the external walls to provide a cut-off from solar glare. The northern half of the new extension


utilised the original east-facing stone garden wall, which required underpinning for stability and support. New precast concrete columns support glulam beams connected back onto it.


Natural ventilation and light Dynamic thermal analysis was used to design the building as fully naturally ventilated. The original office was 24 m deep, and great care had to be taken to control air movements through the redeveloped building. This was achieved by building an atrium pod in place of the courtyard, which draws air from the perimeter through the offices in a controlled manner. The natural ventilation strategy was also tested, using bulk airflow calculations for various wind directions, to ensure that the passive approach would operate correctly throughout the year. The scheme is further enhanced by the use of phase change thermal mass incorporated in the ceiling. Rising energy costs, coupled with the requirement to reduce carbon footprints, make the need for feasible and effective ways to introduce natural light into buildings greater than ever. The existing offices in the deep plan building at Scotstoun House presented considerable challenges to maximising natural light. This was remedied in the redevelopment by incorporating sun pipes throughout. The 90 sun pipes form a zero energy light


source, which is of particular use in the winter months when there is less daylight from the external glazing. The planning constraints required that the building achieve a BREEAM Very Good rating, and again this goal was exceeded by the project being certified as BREEAM Excellent. It was required that a minimum of 15% reduction in carbon emissions by the systems serving the building be provided by low-to-zero carbon (LZC) technology. This planning condition was achieved through the use of a biomass boiler.


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