"Offsetting carbon levels is achieved in several ways. Pixel achieves an extremely low level of base building carbon emissions it uses a special type of concrete, Pixelcrete, which halves the traditional levels of embodied carbon in the mix," says Brady. "The low levels of carbon emissions make it easier to get a carbon neutral outcome, as less renewable energy is required.
"However, it is Pixel's mechanical and electrical services, which are designed to emit very low levels of carbon, that make carbon neutrality achievable."
A central aspect of achieving the Green Star rating is the 100% fresh air systems and strategies employed in the building. These rely on the thermal integrity of a concrete-mass base structure and a thermally responsive building facade both of which Pixel enjoys.
Pixel's operational energy is significantly reduced through the use of active mass cooling (AMC), a system design that uses separate cooling and heating approaches. Cooling is via hydraulic pipe work embedded into the exposed structural slab, providing silent, radiant cooling, with ventilation and additional cooling coming from fresh air delivered through access floors. The thermal mass of the concrete slab allows it to soak up energy during the day without large fluctuations in internal temperature. In winter, the mass then absorbs the warmer air being expelled from the building, removing much of the building's requirement for heating.
In addition, free night cooling, or night purging, is achieved through smart window technology, operated by sophisticated building management software, that automatically opens the windows of the facade on cooler nights to enable the night air to flow into the building and cool the structure.
Besides using natural processes, Grocon imported a gas-fired absorption chiller to add to Pixel's green arsenal an idea originally from Umow Lai. Widely used elsewhere, but a first for Australia, the high-tech chiller uses ammonia as its refrigerant source and natural gas as its energy source. As a result of this technology, the carbon emissions from the air conditioning plant are dramatically lower when compared with electrically powered chiller systems. The use of ammonia as the refrigerant gas in the system means there is no ozone-depleting potential.
All this minimising of carbon emissions is balanced by the usual sustainable energy suspects three improved, and patented, wind turbines are complemented by photovoltaic panels mounted on a tracking device to follow the sun. There are also some fixed PV panels. One far more unusual resource takes the form of biogas, generated in an anaerobic digester from the blackwater off Pixel's vacuum toilet system this energy is used for domestic hot water heating.