Zero Carbon Display Home

The Rural Building Co. is leading by example in environmentally sustainable housing and they brought eTool on board during the design phase to perform an LCA. The goal of the display home was not only design an attractive, comfortable home but also to implement a zero carbon design. This means all the greenhouse gas emissions associated with the construction, maintenance and operations of this project over its lifespan will be offset by generating clean electricity on site as well as planting trees as part of a carbon offset program. This design will meet the high growing demand for environmentally responsible houses and act as an impressive showcase of how a building can achieve zero carbon status without sacrificing the sought-after design aspects of a home.

  • Date: January 2014
  • Client: Display Home
  • Builder: Rural Building Company (
  • Location: Baldivis, Western Australia

Results Summary

Impact AreaTotal CO2e / Year / occupant (kg CO2e)% Saved Against BenchmarkeTool Medal
Embodied Carbon89738 %   
Operational Carbon-453118 %Platinum_medal
Total Carbon444*89 %   

* The remaining carbon will be offset with the purchase of carbon offset credits.

Project features

Engaging with eTool at design stage

The design achieved an eTool gold medal with 89% savings in carbon emissions when compared to a residential benchmark in the same climate zone. eTool got involved in this project whilst in the design phase, which is the easiest and most cost effective point in the project to include sustainability features into the project.

Clean Electricity

A 5.5 kW Solar PV will produce more electricity than the house will use. Although the system has a high embodied carbon component (panels, inverter, frames, replacement), the substantially reduced “Operational Impact” due to the clean renewable energy input back into the grid, will offset this increased “Embodied Impact” many times over during its design life. Reducing the inverter down to 5kw but keeping the 5.5kw panels still enables the future householder to get the feed in tariff and get a large carbon credit with eTool LCA for generating clean electricity.

Solar Hot Water with Heat Pump boost

Hot water use accounts for only 8% of total operational energy as the system is using free solar thermal energy and heat pump boost during those cloudy days. When the system is not taking all necessary energy from the sun, the energy required to heat the water is minimised by transferring heat in the ambient air to the water using a heat pump. Heat pump system coefficient of performance is 2.7 and that means for every unit of electricity it will transfer 2.7 units of heat to the water. Estimated electricity running costs of $70 per year for hot water boosting.

Carbon Offsetting

After implementing the low carbon solutions, the remaining 86 tonnes of CO2e will be offset with Carbon Neutral to bring the design to a net zero carbon outcome. Carbon Neutral offset program often consists of native tree planting in Australia territory.

Additional Features

High efficiency air conditioner and heater

Energy monitoring system

Vents to fridge to increase efficiency of the condenser

7.5 stars thermal performance rating

This assessment was conducted by Henrique.