Lighting in Design March 2015

drawing on the experience of colleagues with other highly transparent buildings in similar climates.The solution was to use double skin facades on the northeastern and northwestern elevations, which were most vulnerable to solar gain. These facades have an outer skin of clear glass, spaced 700 mm outside the main facade.The latter is double glazed for thermal control and forms the building envelope. Automatically-controlled blinds between the inner and outer skins track the sun as it moves across the building.When the blinds are open, the floor-to-ceiling glazing allows good day lighting of the space, with a daylight modelling study indicat- ing that 37.5% of the usable area has a daylight illuminance of higher than 250 lux. The majority of the lighting in the office space was specified as T5 fluorescent lamps with high frequency ballasts. These have proven to be as efficient as LEDs and have guaranteed life spans of up to 18 000 hours. Since a primary focus of the lighting design

The architect and interior designers worked closely with the developer and tenant, and the electrical consultants, to develop a lighting scheme for the building. The primary constraints were budget and the sustainability requirements.The building, which ultimately achieved a 6 Star As Built rating, was initially briefed to achieve 5 Stars under the Green Building Council’s Office Design Rating Tool. A great deal of attention was given to using natural daylight wherever possible.The office areas are all open-plan and have direct views to the out- side. An atrium cuts right through the building and its shape was emphasised by including lighting to the perimeter and feature structural steel elements. Additional daylight was brought to the centre of the atrium via large skylights. The architectural concept called for large areas of glass and, according to Arup façade engineer John Abbott, the glass facade was studied in some detail using energy and lighting simulations and

LiD 03/15

5