How a single mum designed and built an energy-efficient home for $260,000


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Location, light, open plan living, a swimming pool - there are a few features that Australians prioritise having more than others in a home. And increasingly, energy efficiency is joining that list.

Given that energy-efficient homes tend to come with much lower - if not zero - energy costs, that's hardly a surprise. And that's without taking into account the added benefit of reduced emissions.

Two in three respondents to a survey conducted by in September considered energy efficiency ratings to be an important factor when buying, building or renting a property, while a third (34%) said it was extremely important.

sophia macrae net zero home

Sophia MacRae is one person who certainly sits squarely in the 'extremely important' camp. For three years MacRae has been the proud owner of an all-electric, low-bill home in the town of Camperdown in southwestern Victoria - a home which she designed herself and had built on a single income.

While keen to spread the word about the benefits of energy efficiency, MacRae is also determined to share her experience of designing and building a home to help encourage other low income households wanting to do the same.

"Being a single parent and having experienced poverty and living in a precarious situation, I know what it's like, and I want every single income household to know that they shouldn't be put off.

"Don't feel like it's going to be too expensive. You can do it. It's worth it. You can have a really comfy house with really low power bills."

Buy, design, build

It wasn't always MacRae's plan to design and build a house from the ground up.

"I was looking around town to buy an existing house, but everything was leaky and facing the wrong way, so I thought there was no point - I would have to get some vacant land and do it from scratch myself to get it right."

She soon found that land: a 526 square metre block in Camperdown. Though MacRae readily admits that purchasing a similar block today would be next to impossible for the $55,000 she paid in 2018.

Next came the design process. MacRae had recently obtained a Master of Sustainability and a Master of Planning at the time, so it's fair to say that she started the process with more know-how than most. However, that's not to say the process was without its snags.

"I spent about a year designing a beautiful house that I loved which was going to have an eight star energy rating, but it turned out that it was going to be too expensive for me to build. So I went back to the drawing board and realised that it would be better to do a prefabricated house.

"I contacted a business in Ballarat and they were very open to me redesigning what they already had on stock, so after another six months of designing I signed the contract with them to do the build and they built the house in four months and delivered it onto my site in June 2020."

How much did it all cost?

So, the million-dollar question: what was MacRae's total outlay to purchase a piece of land and build an energy-efficient home? As she explains, the answer is far below $1,000,000.

"The contract I signed for the house was about $160,000. Then the design changes I made to make it more efficient - basically by adding double glazing, having it all electric with an induction stove, installing a heat pump hot water system and having better insulation - that added $10,000 to the price.

"With a prefabricated house you do have to pay for your own plumber and sparky to connect it in, so all up that cost about another $30,000 for those services. And also putting in a driveway."

Last of all came the solar system. Unsurprisingly, this was a feature that MacRae didn't want to skimp on, so she had a 10 kilowatt system of high quality panels installed for around $10,000 which she says is good enough to generate energy during winter and even when it's overcast.

"So with the land, the house and all the other work and installations I had done, the total came to around $260,000, $270,000 to create a house that has virtually zero power bills."

Key energy efficient features

By July 2020 MacRae had the keys to her new home and was not only delighted with how it had turned out, but felt that her design choices had been vindicated. Perhaps the most vital of these was her decision not to position the house adjacent to the street.

"I put it on an angle to the street so that the living areas of the house at the back of the house face north rather than in line with the street. And my block was able to accommodate that, even though it's small, which means that I've just got this really lovely, light space.

"That was the most important thing, because once it's constructed, it's very difficult to change the house - and the areas that you want to hang out in - to face north."

How important are energy efficiency ratings? 

After the orientation, MacRae says that having the right eaves and proper insulation are two other crucial elements to ensuring temperature control in the home.

"Make sure that you've got eaves that are the right length so that all the free heat and natural light can come in during the winter, and then none of that hot heat touches the glass in the summer. And that is the simplest way to have a comfortable house."

"Then you want to make sure that there's not going to be any leaks and drafts in the house and you want to make sure that the insulation - particularly the ceiling insulation - is as good as it can be.

MacRae was also adamant about not having gas. There are a couple of reasons behind this, the first of which is that the solar system she had installed would provide ample energy for the home, but she also believes that having a gas connection will be a turn-off for buyers in the future if she ever sells.

What are the energy bill costs?

For many, the major motivation of having an energy-efficient home is to lower energy usage and energy costs, so how does MacRae's actually stack up on this measure?

As MacRae explains, her monthly energy bills don't read as zero because of the fluctuation in both her own energy needs and the output of the solar system, but over 12 months she pays next to nothing.

"During the winter time I might end up using 60-70 kilowatt hours a month which they may charge me $80 for. And during that same month in winter my solar will have only earned me about $20, so all up I have to pay the retailer $60.

"But during autumn and spring it starts to work out much better because they're only charging me $40 for the electricity I've used for the month and I've actually sold $30 back to them.

"Then you get about five or six months of summer where there's more natural light and I don't need to use any active heating or cooling. So they may charge me $25 for a month's electricity but I will have sold $50 or $60 worth of juice back to the grid."

In fact, while many Australians will be sweating it out over the summer and seeking refuge in front of an air conditioner, MacRae says that she finds it to be one of the most pleasant seasons to be in her home.

"It's an awesome time of the year because my house is naturally cool. There's no heat hitting the glass in my house, and it's so well insulated that it's just cool."

Interested in learning more about home energy efficiency? Check out our affordable renovations for an energy efficient home article, or find out more about Sophia MacRae's home-building journey, including a look inside her home, by watching episode 22 of The New Joneses Electrify Everything web series.

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Tom Watson is a senior journalist at Money magazine, and one of the hosts of the Friends With Money podcast. He's previously worked as a journalist covering everything from property and consumer banking to financial technology. Tom has a Bachelor of Communication (Journalism) from the University of Technology, Sydney.