Glasgow’s G1 Building on the south side of the city’s George Square was once the city’s main post office. It now houses 120,000 sq ft of office and restaurant space behind its Grade A listed façade. Ramboll’s building services and fire engineers designed energy-efficient systems that enabled maximisation of the total lettable area of the 12-storey building.
The services design provides flexibility, allowing for separate metering for two tenants per floor on each of the building’s eight office floors, with further provision in the basement and on the roof for the installation of tenant plant. Air-handling units and chillers have been custom made to fit the comparatively small roof space. The two chillers circulate water to each floor’s ceiling-mounted fan coil units, while fresh air is filtered and heated via the air handling units. A fully networked building management system controls and monitors all plant and equipment.
The building is served by six passenger lifts with sophisticated destination control systems linked to the access system. This channels passengers to the most appropriate lift for their required floor, improving traffic flow at peak times. There are also two fire-fighters’ lifts at opposite ends of the building.
G1’s listed status precluded the following of standard building regulations for fire protection in certain areas, so our engineers liaised with the local authority to ensure the flexible solution developed design met safety standards. Using 3D modelling, engineers demonstrated that a 30-minute reduction in structural fire protection on the upper three floors was justified.
They also showed that an accommodation stair between the 8th and 9th levels was an acceptable alternative to having these floors as separate fire compartments. Similarly, they demonstrated that it was feasible to have openings in the floor between the basement and ground floor. Omitting fire protection to certain secondary beams and terminating the fire-fighting lift at the 7th floor met the fire safety standards and saved the client money.
We delivered value by using environmental modelling to simulate the building’s energy performance, taking into account its north-facing aspect and shading from neighbouring buildings. This demonstrated that a proposed central atrium would fail to deliver adequate daylight to all but the top levels, and it was subsequently omitted. The building achieved an energy performance certificate rating of B, unusual for similarly configured buildings, and a Very Good BREEAM rating.