House with No Bills Experiment Finishes With Far-Reaching Learnings Realised

The ‘House with No Bills’ experiment has now concluded, with the study revealing far-reaching learnings both in terms of energy-efficient home design and education.

As part of Mirvac’s mission to drive a more sustainable future for Australians by reducing environmental and social impacts in residential living, the prototype energy-efficient House with No Bills was launched in 2018 with a ‘typical’ key worker family of four winning the chance to live in the home, learn more about sustainable living, and enjoy a life free from rent or bills.

The House with No Bills study integrated extensive energy modelling analysis with the input of researchers at Curtin University to measure the energy [generation and] use of a 199 square metre, three bedroom home in our Jack Rd estate in Cheltenham. Eco-friendly design and technology innovations incorporated into the House with No Bills to reduce its reliance on grid electricity included an Evergen solar and battery system featuring CSIRO-developed intelligent energy management, a smart home automation system with environmental sensors to control internal temperatures, lighting motion sensors and automated blind control, increased roof insulation, high-performance glazing, energy-efficient appliances and LED lighting.

Selected partly for their expected ‘average Australian family’ energy usage (with two teenagers and both parents working) and partly for their minimal prior education around living sustainability, the Zimmerman family documented their experiences and learnings monthly, with smart meters and monitoring systems helping to keep track of where and how energy was being used.

Although not quite reaching the ambitious zero energy bills target, the results from the study were compelling, with learnings already being applied to other Mirvac projects. Across 12 months, the House with No Bills used only eight per cent more electricity than it generated, and operated as ‘energy positive’ for five months. The House with No Bills also achieved a 75 per cent energy saving (approximately $2,000), with the very real possibility of the home having zero energy bills in future. Curtin University identified that the remaining $715 energy bill could be eliminated with minor design and behavioural changes.

For the Zimmerman family, the House with No Bills proved to be a life-changing introduction to becoming more energy efficient, while giving them a chance to start saving for a home deposit and achieve other goals, such as studying, without the financial stress of paying rent or bills. 

“Our journey to becoming more sustainable as a family saw us on a steep learning curve. We realised with the help of the Mirvac and Curtain University teams that our behaviour and simple choices around the home have a large impact on energy consumption. Understanding how to use the energy monitoring apps was really important and once we started to see the impact of different decisions, that influenced our behaviour,” said Lisa Zimmerman.

“Sometimes the results were really surprising too. We expected the home’s solar panel and battery system to have the biggest impact on energy savings but some of the smaller decisions can also have a big impact. I am forever reminding the kids to turn off lights but it was interesting to learn that with the technology we had in the home, lighting made up only two per cent of our total energy consumption. It was things like taking shorter showers and turning off the TV and games console when not in use that can make a real difference.” 

This pioneering project achieved its aims of encouraging people to learn about the wider environmental, financial, social and well-being benefits of sustainable living. The House with No Bills prototype home has already shaped future projects, and will continue to influence the design of sustainable homes in the future.

Mirvac General Manager for Residential Victoria, Elysa Anderson, said the House with No Bills had been a landmark project, attracting wide-spread attention.

“Designed to look, feel and operate the same way as a typical home, the House With No Bills experiment aimed to help address the increasing pressures of housing affordability and reduce environmental impact with market-based solutions,” she said.

“The Cheltenham property was home to the Zimmerman family until December 2019, while they lived rent free and learned to live sustainably, without the stress of soaring energy bills. The family’s experience showed that not only is smart energy design and technology crucial for reducing energy consumption, education is also key.” 

“The solar and battery system installed in the House with No Bills significantly offset energy use from the grid, noting that Melbourne is one of the least sunny Australian cities. Overall, the home was very close to generating as much energy as the family used without too much modification to their normal behaviour.”

The House with No Bills was sold under the hammer on Saturday 29th February by RES by Mirvac.