14,250 sq m size of the building, the number and variety of systems present and the fact that many of these include manual override options. As a result, the final solution is far from straightforward and the task of integrating the various engineering systems into an energy-efficient solution should provide a challenging, hands-on learning experience for staff and students alike.
Ventilation strategy Most of the rooms are naturally ventilated as part of the low-energy design (see box on page 30). According to Mooney, the designers have gone to great lengths to ensure a comfortable environment, while also empowering the students. ‘It is critical the occupants are in direct control of their environment,’ he says. Rooms without windows are also naturally ventilated. The single-storey, high-bay laboratories in the centre of the ground floor utilise a series of
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chimneys and opening roof lights. Penthouse louvres on one side of the laboratories supply fresh air, drawn from the lightwell above. Air is exhausted through a series of chimneys on the far side of the room and discharged, four floors up, at roof level. Modulating dampers in the supply and
exhaust ducts independently regulate the amount of air entering and leaving the laboratories, based on room temperature and CO2 levels. Both dampers are fitted with a manual override switch. In addition to the supply and exhaust chimneys, the high-bay labs have rooflights that open under control of the building management system (BMS); again these have a manual override. On days when the natural ventilation
system is ineffective, the supply and exhaust chimneys are fitted with booster fans, which are under individual control of the BMS. Students, however, can override the speed controller using a wall-mounted switch in
order to modulate the fans’ speeds. The laboratories on the ground, first,
second and third floors of the western elevation are too deep to be ventilated using windows alone. Instead a hybrid solution of opening windows and stack ventilation is used. The windows ventilate the area of the room closest to the façade, while the area furthest from the windows is ventilated using stack ventilation through chimneys positioned to draw air across the laboratories. Air flow rates are controlled by modulating dampers in the chimneys, operated by the BMS. On the top floor, where stack ventilation is limited, the chimneys are also fitted with booster fans. ‘This scheme proves that by spending a little more money you can be energy efficient,’ says Mooney. To minimise winter infiltration load, additional air is drawn into the laboratories from the circulation corridor. This in turn draws air from other labs and from the
January 2012 CIBSE Journal 29
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