The Cooperative Research Centre for Low Carbon Living (CRC LCL) research project Mainstreaming Net Zero Energy Housing aims to improve industry understanding of Net Zero Energy Homes (NZEH) while addressing cost and consumer interest barriers. The project also provides a unique opportunity to increase collaboration between industry players such as land developers and volume builders.
This report explores cost-efficient approaches for the participating volume builders to transition 'business-as-usual' house design to a 'net zero energy' house design. The methodology involved firstly a workshop, where the concepts of NZEH design were discussed amongst stakeholders and different design and technology scenarios were brainstormed. The second step was to model the chosen scenarios with the use of the CSIRO AusZEH Design Tool and cost these to identify the most cost-effective solutions. Finally, an adequate PV system was sized to cover the annual energy needs of a typical Australian household in order to achieve NZEH.
The results deriving from the workshop and subsequent modelling were used to inform the house design to be built in four different locations across Australia including Melbourne (Victoria), Townsville (Queensland) and Canberra (Australian Capital Territory) and Perth (Western Australia). The following were some of the key findings:
- Major energy efficiency gains were obtained mainly from additional insulation, glazing upgrades and energy efficient appliances (hot water systems and air conditioners in particular);
- Only a relatively small sized PV system (3-4kW) is required to cover the net needs of a typical Australian household provided that the building envelope is designed appropriately for the climate and the appliances are energy efficient;
- A collaborative environment enables builder engagement and win-win solutions to be developed.
Subsequent reports by the authors document the latter stages of the project, including an analysis of the construction costs and estimated payback periods of the NZEH design and technology features of the case study homes, as well the results of visitor surveys being undertaken to identify consumer interests. The results of the three project stages will provide a valuable evidence base for better understanding the upfront cost implications and ongoing operational cost benefits of NZEHs, as well as an insight into market interest in NZEH design and technology features.