The Cooperative Research Centre for Low Carbon Living (CRCLCL) 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.

Based on energy modelling conducted in the design review process and retail costings provided by the builders, initial installation costs and annual savings were calculated. The costing analysis was then conducted across a 25-year lifespan, aligning with previous research on high performance buildings, as well as placing the analysis over a similar time period to a standard mortgage. The analysis used energy prices for each of the four case study locations and accounted for maintenance and replacement costs of appliances. Analysis was conducted across five different electricity market scenarios including increased electricity prices, continuation of feed-in tariffs, and elimination of feed-in tariffs.

The key findings are:

• Solar PV and Heat Pump or Evacuated Tube hot water systems are the two most cost effective upgrades across all case studies. Both of these upgrades show payback within 10 years at current energy prices.
• Thermal shell upgrades provide effective and meaningful cost reductions, however increased installation costs compared to the standard house design pushes payback beyond 10 years. In most cases, given the extended lifespan of the thermal shell, these savings outweigh the costs over the 15 year analysis period.
• NPV of NZEH upgrades is positive under energy price increase scenarios.