Mark Barrie from Norman Disney & Young (NDY) makes the case for green retrofitting Australia's commercial building stock with an interesting example his company is involved in. 
Energy efficiency, carbon footprint reduction, recycling and re-use have become accepted terms within our everyday vocabulary as public awareness of climate change issues receives increasing attention within our society. While issues like household recycling, water conservation and transportation remain important, the emphasis in Australia has started to shift towards energy consumption within the built environment.  
According to estimates from the Department of Climate Change and Energy Efficiency, commercial office buildings in Australia account for just under 10 per cent of the nation's total greenhouse gas emissions. This massive operational footprint of our built environment represents a significant area of focus for energy efficiency and carbon improvement.   
In response to the significant levels of energy consumption associated with the built environment, legislation influencing building designs and construction techniques have evolved over time to improve energy efficiency and reduce CO2 emissions. Measures such as the BCA section J, Green Star rating tools and the NABERS assessment tool have delivered significant improvements in the performance of new commercial buildings but have had limited effect on existing building stock. Within the current financial climate, the rate of new buildings being constructed will not significantly influence the total carbon emissions expended by the overall existing commercial building stock. Accordingly any fundamental improvement to the built environment must focus on the adaptive re-use of existing commercial buildings to achieve the greatest levels of energy reduction and carbon improvement.  
There are a number of philosophies that will mitigate building emissions and the approach currently being undertaken at 1 King William Street in Adelaide by the design team, including NDY on behalf of Anvil Capital, demonstrates a proactive example of adaptive re-use for a substantial existing commercial building. This high profile commercial tower was constructed in 1965 and has an NLA in excess of 18,000 sqm. This existing building currently performs as a 2-star NABERS building however the design team including NDY are developing a suite of sustainable strategies that can deliver a 5-Star NABERS, 4.5 Star Green Star performance. The proposals have been developed on the principle of multiple small improvements and can be delivered for significantly less capital cost than demolishing the existing building and constructing a new one on the same site.  
The sustainable philosophies proposed for the existing building are integrated to complement the building's operation and energy load-mapping.  During the cold winter months the gas-fired micro-turbines will generate heating and domestic hot-water for the building through heat recovery of the waste, flue-gas while the off-grid generated electricity will supply the large air-handling unit base-load at significantly less carbon intensity than drawing an equivalent amount of electricity from the local grid. During the warm summer months the waste heat from the gas-fired micro-turbines will produce cooling via an absorption chiller reducing the electrical cooling demand on the building, the off-grid generated electricity will supply the large air-handling units and roof-mounted photo-voltaics will assist with the building's electrical demand during the period when the electrical (cooling) demand is at its greatest.   
New solar shading devices are proposed on the building's north façade and these will reduce the overall heat gain and subsequent peak cooling load during the summer while still allowing the building's tenants an un-obscured view of the sky. Re-sealing the existing single-glazed windows and providing additional insulation to the external façade will improve the buildings thermal heat loss/gain performance and reduce the effect of unwelcome infiltration. 
The simulation and modelling exercise carried out by NDY demonstrates that the base building's existing greenhouse gas emissions will be reduced by over 65 per cent or 1,560,000 kg CO2/yr.  From the design team's review, this can be achieved for a cost significantly less than demolishing this significant landmark building and constructing a new one in its place.    
In considering the volume of Australia's building stock and the opportunity for significant carbon reduction, an approach where existing buildings can be re-used, re-invigorated and future-proofed, truly reflects the spirit and essence of a sustainable design approach. 
Mark Barrie is the ESD manager in Melbourne for NDY and has a track-record of innovative, sustainable design within the built environment.