Urban centres are a major source of greenhouse gas emissions and energy use. In Australia, Building energy use is responsible for 23% of greenhouse gas (GHG) emissions, more than half of which comes from the residential sector (CIE, 2007). In Australian residential homes, about two thirds of energy is used for heating and cooling (incl. water) (CIE, 2007). Residential (and commercial) space cooling is forecast to rapidly increase by up to 16% per annum (DEWHA, 2008), but will still only represent 4% of total residential energy consumption in 2020. However, the problem of space cooling on hot summer days is a key issue to sustained electricity provision at times of peak demand. The urban heat island and extreme summer heat waves both intensify the cooling load that residential, office and commercial buildings experience, and consequently that the occupiers may experience. Trees can reduce the cooling load through direct shade, and cool the external micro-climate through transpiration. Trees require rainfall or irrigation to provide these benefits, otherwise these benefits are limited and tree health suffers.

The aim of this study is to directly quantify the reduction in cooling loads upon external walls from the presence of deciduous exotic or evergreen native trees in a Melbourne climatic context. The water use of these trees will be quantified concurrently to gauge temperature reduction benefit in consideration of water uptake cost. Several hypotheses were contructed to be tested:

· Deciduous tree shade will provide greatest reduction in summer thermal load and inward heat transfer.

· Deciduous trees will enable greater winter warming of external wall temperatures and reduced outward heat transfer.

· Tree water use and external wall temperatures will directly relate to daily solar radiation received.

External wall temperatures and wall heat transfer rates were measured on three single-room weatherboard buildings at the Burnley campus of The University of Melbourne: i) evergree native trees placed on the west and north walls, ii) exotic deciduous trees placed on the west and north walls, and iii) no trees (control).

The State of Australian Cities (SOAC) national conferences have been held biennially since 2003 to support interdisciplinary policy-related urban research.
This paper was presented at SOAC 5held in Melbourne from 29 November – 2 December 2011.
SOAC 5 was hosted by the University of Melbourne, RMIT University, Monash University, Swinburne University of Technology and Latrobe University as well as the Australian Housing and Urban Research Institute and the Grattan Institute, the Victorian State Government and the City of Melbourne.
Three plenary panels brought researchers from across the country to address ‘big issues’: place-based disadvantage, the design and form of Australian cities, and metropolitan governance. Over 175 papers, in 46 themed sessions, cover topics ranging from planning and governance for environmental sustainability, to housing affordability and adequacy in the context of an aging population. Healthy communities, better public transport, high quality open space, participatory planning, and issues affecting the peri-urban fringe are also strong sub-themes within this conference.
All published papers have been subject to a peer reviewing process.