Conservation House is the first office building in New Zealand to utilise a chilled beam system as a means of controlling indoor environmental quality. The system is based on the use of both water and air to control the internal environment. Cold water circulates through a cooling coil and as the surrounding air is cooled it descends into the office space, replaced by rising warmer air, creating an airflow cycle.
The Wellington Company in consultation with and at no expense to DOC initiated and installed an active chilled beam system for Conservation House. In an active system pressurised air is discharged through a number of nozzles causing induction of the air in the room, resulting in the rate of the air-flow cycle being more constant, says director Ian Cassels.
Because chilled beam systems have no moving parts, service and maintenance of the system is simpler. Another benefit of the system is that no noise is produced. In fact, DOC have had to introduce pink noise as the building is too quiet.
The chilled beam system is supplemented by the double layer glass facade and atrium. Fresh air from the rooftop comes down through the atrium and return air moves by convection back up to the rooftop through the void between the double facade.
"As well as working to circulate air, the atrium allows natural light to penetrate deeply into the floor plates, while exposed concrete ceiling surfaces are used as thermal masses to absorb excess heat generated during the day, and night ventilation will be used to flush the building at night," says Cassels.
Waste heat is also captured by the building's heat pumps and used in the heating of hot water. Increased natural light means less of a dependence upon artificial light and a Digital Addressable Lighting Interface (DALI) system allows for automatic daylight dimming of the perimeter lights. High-efficiency, low-mercury lamps and solid-state, long-life LED lamps are used throughout the building, minimising not only energy consumption but reducing the environmental impact of disposal at end of life, says Baker.
Other mechanical strategies incorporated into the building include collected rainwater used in the bathrooms, kitchens and for garden irrigation. Low-flow fittings and fixtures with motion detectors have been installed in the bathrooms to further reduce water consumption. Additional staff behaviour strategies, designed to reduce energy consumption, consist of a large bicycle park and location next to a well-serviced bus stop, providing transportation alternatives.
Working in concert with the environmentally sustainable practices initiated by The Wellington Company, DOC instituted its own pro-active elements into the fit-out.