Case study: The Carbon Positive House
Annie Kane | 12 November 2015
When you think of building your dream home, what do you imagine? For me, it’s creating a warm, open space filled with natural light, that is energy efficient (better yet, produces its own electricity) and made from sustainable materials. Oh, and there are killer views to boot.
But, having watched one too many episodes of Grand Designs, I’m aware that building your dream home can turn into a nightmare if deadlines are missed, which can lead to rising costs and delays to construction.
So, what if you could have your dream home built in a weekend? Better yet, a day? Architectural and building firm Archiblox seems to have come up with the answer, with a sustainable house that can be constructed in just six hours – less than the average person’s work day.
Bill McCorkell, owner and director of the Victoria-based company, jokingly told The Fifth Estate: “I’d really like to tell someone to go out and whilst they’re away, I’d make them a new house!”
So how are Archiblox able to achieve this feat in engineering? It comes down to the fact that their new, timber-framed house is prefabricated offsite over a period of six weeks and then put together on site over a few hours.
“The beauty of prefabricated homes is that one part is worked on by carpenters and labourers, then it gets passed down the line and other teams work on it, until it’s completed. Then we can just transport it to where it’s needed and put the components together,” McCorkell says.
“Historically, in Australia, people have viewed transportable, prefab houses as cheap and nasty. But we thought we could buck the norm and make something transportable with high architectural merit.”
What makes the house most impressive, though, is not the speed at which it’s constructed, but the fact that it is a showcase in sustainability.
“We set ourselves a task in 2014 to create the world’s first carbon-positive dwelling in Australia to make a positive change. We wanted to create buildings with healthy materials and encourage occupants to engage with the building and the climate that it sits within”, the architectural firm said.
So, the company – which already specialised in prefab buildings – went about designing a house that produced more energy that it needed. What they came up with was the Carbon Positive House.
“We call the house Carbon Positive, because we’re positively putting energy back into the grid. This is due to the five solar panels mounted on the roof that produce electricity, and the fact that the house requires no mechanical cooling or heating,” McCorkell says.
The five-kilowatt hour solar panels produce more energy than needed to power the hot water system, LED lights, and appliances – so excess can be exported to the grid. Meanwhile, the house’s “conservatory” – complete with removable shades – acts as a natural cooling and heating system.
“The conservatory, which runs across the whole width of the building, acts as a radiator during winter, but then helps cool the house during summer. That is because it creates a higher air pressure, which gives the ability for cool air to be sucked in through cool tubes [installed in the ground], which can be taken through the house and out through the high windows.”
Insulation is also a key factor in keeping the house at the right temperature, and, as well as utilising FSC-certified timber for the frame, double-glazed windows and slideable living walls and roof to reduce sun penetration through the main building, there are a couple of “cool ideas” being utilised too.
For example, the garden beds on the living walls contain moist bags, so that when air passes through, it picks up moisture, which has a cooling effect. There’s also a phase-change material in the ceiling, which forms into a liquid over 18°C, allowing warm air to more readily pass through. Once the temperature drops, the liquid solidifies, retaining heat.
The sustainability and health-impacts of the materials used within the house were considered too, with all the materials either being carbon-neutral, or manufactured through carbon-neutral processes. There’s even the option of installing a grey water recycling solution.
“Our solution was for the design, materials and working life of the building to be sustainable,” McCorkell says.
“As an architect I find wood pretty cool to use – I like the look of it aesthetically, and the fact that it provides warmth and flexibility whilst being stable – but we made sure it was all FSC certified. There’s also no formaldehyde or VOCs within the materials, or carcinogens in the glues, sealants or paints, so they are really healthy products that we’ve put in the space.
“We’ve also tried to ensure that the major components of the fabrication are Australian made, rather than imported, to save carbon emissions.”
In fact, Archiblox’s life cycle assessment (which received Australia’s first residential platinum award from eTool) suggests that over its life span, the Carbon Positive House will emit 1165 tonnes of carbon less than the average building providing the same functionality – equivalent to planting around 7000 trees or taking 307 cars off the road.
Making every new home carbon positive by 2040
The design for the house is already making waves in architectural circles, with the Carbon Positive House winning the Arch & Design Sustainability Award for Single Dwelling, the International Green Interiors Award for Residential New Build, and is currently shortlisted in the top 10 finalists for the UN-supported Sustainia Awards (the winner of which will be presented at the World Climate Summit in Paris on 6 December), which celebrate ground-breaking sustainability solutions.
“We believe that we have a great opportunity to educate people and encourage our clients to think differently on how they can interact with their houses, and the communities that they live in,” a company release said.
“We want to create a movement that redefines the built environment industry in Australia, with the intention that every new home built in Australia is carbon positive by 2040, and every existing home has access to retrofitting solutions to become carbon positive.
“With ecological innovation comes economic benefit. By introducing innovations that reduce energy usage we are talking about reducing household utility expenditure down to next to nothing. We see this as a total reinvention to the cost of living.”
So what exactly is the cost of this reinvented living? The standard one-bedroom, one-bathroom model (Carbon Positive House 01) comes with a starting price of $286,000 – with larger models going up to around half a million dollars.
I’m going to start saving now.
Find out more about Archiblox’s Carbon Positive House.