There is a general recognition that the existing housing stock represents the largest potential for energy saving and greenhouse abatement in the residential sector. However, few studies have looked at how inefficient existing houses actually are, the extent to which their level of energy efficiency can be practically upgraded, or the cost and cost-effectiveness of doing this. In 2009 Sustainability Victoria commenced a program of work to address these information gaps. Through the On-Ground Assessment study data was collected from a reasonably representative sample of 60 existing (pre-2005) Victorian houses and used to: determine the energy efficiency status of the houses; identify the energy efficiency upgrades which could be practically applied to the houses; and, to estimate the upgrade costs and energy bill savings which could be achieved.
The results presented in this report are estimates based on modelling, using data collected from real houses which have been assessed to identify the upgrades which can be practically applied. The next phase of our work on the existing housing stock is to implement energy efficiency upgrades in houses and assess the impacts achieved. Through the Residential Energy Efficiency Retrofit Trials we are implementing key energy efficiency retrofits in existing houses and monitoring the impact to assess the actual costs and savings, the impact of the upgrades on the level of energy service provided, and the householder perceptions and acceptance of the upgrade measures.