This environmental engineer’s answer to passive solar design is a “glimpse into the future”

Rose Mary Petrass

Djildjit Martin Anda

Utilising recycled timber and the thousands-of-years-old construction material of rammed earth, the “Djildjit” home in Fremantle WA is environmental engineer Martin Anda’s answer to the passive solar philosophy.

When Martin Anda was in the market for a new home, he decided to go the unconventional route and buy a piece of land with his friends. The 274 square metre north-facing lot in White Gum Valley, Fremantle, Western Australia, was already located within an existing One Planet Living-certified eco village residential precinct when he and his friends made the purchase. 

The main drawcard was of course, the north facing orientation.

Now, four years after construction, Martin’s 7.7 star all-electric apartment has been featured on Sustainable House Day and Gardening Australia. Martin lives with his wife in one 60 metre square one-bedroom apartment, with another couple living in the other apartment. 

Today Martin and his wife not only reap the benefits of lower electricity bills and comfortable living, but they also have a fully-established edible garden on the property which provides the couple and their neighbours with fresh herbs and a beautiful aspect all year round. 

The Green List caught up with Martin recently to ask him all about the process of building a sustainable home. 

The biggest challenge, Martin says, was the cost. What was initially a financial decision (to build with friends) ended up being slammed with a price tag of $800,000 ($6667 per square metre) – far more than the WA average price of $1258.77 per square metre in 2018. 

“We freaked out when we first saw how expensive it was going to be to build it,” Martin told The Green List

After haggling the construction cost down to $400,000 plus another roughly $100,000 for the landscaping, decking and sustainability features, the total price of the duplex came to just under $450,000 per unit, including the cost of the land itself. 

Working with architect Richard Hammond, the group chose to go for materials like rammed earth walls with recycled materials – which Martin says cost more than brick would have – but some things they just “weren’t willing to compromise on”. 

After a traditional Indigenous Nyungar smoking ceremony to bless the land (the home is named “Djildjit” as a nod to the Traditional Owners’ word for “fish”), sustainable home builder Craig Bailey of Ecovision Homes set to work on putting the vision to reality. He told us that some of these more unique features in the home are actually not as unusual as they seem. 

As a building method, rammed earth is one of the most sustainable materials to choose in home design. One ton of newly manufactured bricks releases 258 kilograms of carbon emissions. By some estimates, the production of cement and bricks could be responsible for 7-8 per cent of global CO2 emissions. 

Unlike brick manufacturing, rammed earth doesn’t require firing, which means no greenhouse gas emissions. But it’s also unfortunately a lot more pricey than traditional bricks. 

“Rammed earth has been used for thousands of years… It’s not like bricks. You construct it by pouring it in from the top. It’s a premium to do a rammed earth wall – as it’s used architecturally as a rustic natural finish, it’s probably double the cost of bricks,” said Craig.

But the cost is balanced out by the benefits of passive solar, which reap savings of approximately $1500 per year. 

“In the house I used to live in before, the bills were enormous… Now we have a heat pump running on solar, so it’s a lot less. I believe it’s around half the price.”

Martin says his number one piece of advice to all home builders or buyers is to orientate their home north. 

“That is the best thing to do to achieve sustainability at lowest cost and return on investment.”

Craig, who has been a practising structural engineer since the 1970s and has worked with experimental materials and practices such as straw bales and passive solar, says that a north facing aspect is the most important thing that developers need to think about when subdividing land for development. 

“The damage is done when the developers subdivide without setting up the blocks in a passive way,” he says. 

“In Perth, the breezes come from the south-west, so you need windows from that side to let ventilation through, but shaded enough to reduce the heat load.” 

Aside from rammed earth, other sustainable materials used in the design included thermally broken double glazed windows, uPVC frames, recycled timber from specialists Remill, and other reused materials. Martin says that people considering building their own sustainable home need to “think seriously about materials of construction and where they’re coming from”.

Aside from a 5.5 kilowatt PV system, the home is made off-grid with a 5000 litre Garantia underground rainwater storage tank. The airtight house design is complemented by an emphasis on natural cross-ventilation, natural light and plants for air filtration. 

And aside from indoor plants, the couple keeps fruit trees, tomatoes, lettuce, sweet potatoes, leeks, and a worm farm to top it all off!

Builder Craig is impressed by what they managed to pull off – and encourages others to do the same. 

“If you take sustainability principles and do what Martin Anda did and take it to the next level, you can make it very advanced. For example, he has a heat system that tracks the energy use in his home and uses latent energy in the house and walls. It was considered too advanced to be cost effective – but it is the future. 

“[The home] takes it to the next level – it’s a glimpse into the future. One of the biggest myths is that if you incorporate sustainability into your home, it will cost more. But that’s not true. Sure, you can take it to an incredible degree and it will start costing a lot more – but at a basic level it won’t cost anything extra.” 

Craig says that sustainable homes are starting to become more and more popular. 

“Clients want to future-proof. They want a house that will be here in 10 years and won’t degrade in value.”