Greenhouse 5.0

Joost Bakker is one of sustainability’s most provocative advocates. He challenges cherished ideas and leaves nothing to sentiment. His latest project in Melbourne is no different. He doesn’t care for timber, says food needs to be grown in the home, and that off grid will be the future.

In the fifth iteration of Joost Bakker’s zero waste, self-sustaining “greenhouse” prototypes, this time in the heart of Melbourne’s Fed Square, he has gone to great lengths to omit materials that he couldn’t safely eat or drink.

In fact, he believes the 87-square-metre, two bedroom home could be certified organic.

“We want to design buildings the same way you approach a food system.”

The walls, floor and ceilings of the three-storey home are made from a straw-based panel called Durra Panel. The durable, fire resistant panels are made from one of the most ubiquitous wastes on earth, according to Bakker, the hollow stalks leftover from harvest of barley, wheat and other crops.

Straw is a problem for farmers because it takes so long to break down, with many choosing to burn it. Durable, fire resistant panels are now being made in Australia, though Bakker says it’s mostly used in stadiums and performing arts centres for its superior acoustic qualities.

Perhaps more surprising is the steel frame (not so much edible, but it is what cookware is made from) of Greenhouse 5.0. Bakker has been an advocate for steel for some time, attracting criticism from some quarters due to its carbon-intensive fabrication process.

But it’s easily and commonly recycled and when you start talking about one of steel’s increasingly popular replacements, timber, things get complicated.

While timber might lock carbon away, Bakker says it comes with a whole host of other sustainability issues.

“There’s no FSC [Forest Stewardship Council] timber in the building as it’s such a destructive industry.”

He says the rise of monoculture plantations to meet growing demand for timber buildings is wiping out wild forests and damaging biodiversity in many regions.

“There wouldn’t be a tree left on earth if you started building all buildings out of wood.”

He also questions the recyclability of timber due to the glues and chemicals used in some products.

Bakker says it’s “probably easier to climb mount Everest” than it is to build a house out of materials that don’t cause the earth and humans harm or create waste and pollution.

Even in the green building space, avoiding polluting and harmful materials is not exactly established practice.

Bakker says he won’t work with the Green Building Council because it doesn’t rule out enough toxic materials. He likes the Living Future Institute’s long Red List of materials to avoid, however, and has worked with the organisation on a couple of projects, including the Burwood Brickworks shopping centre.

Timber is okay if it’s grown in the right place

Timber does feature in Bakker’s projects but only if it’s come off a farm. He’s an advocate of agroforestry, a land management strategy where more trees and shrubs are grown on farmland with some left longterm for rewilding and some harvested for wood products.

All this is possible in Bakker’s vision for the future where our cities become our food bowls, freeing up agricultural land. That’s what he’s tried to show with the latest greenhouse project: That it’s possible to live in homes that grows all or most of the food a household might eat.

“If the average house is covered in soil you could grow so much food.”

The home is a completely closed loop system that wouldn’t work without people living in it: Inhabitants will grow food on the rooftop garden and breed mussels, yabbies and barramundi in an aquaponics system.

There’s a mycelium wall that will grow mushrooms with nutrients from used coffee ground and steam trapped by the shower.

There’s also a biogas digester that will transform food waste into fuel to power the stoves in the kitchen, which resident chefs Jo Barrett and Matt Stone will use to cook up meals for small groups of guests in an intimate home-restaurant setting.

Bakker’s focus in the past has been on taking restaurants zero waste. His latest project aims to get even closer to the heart of our food woes by bringing food production into the home.

“For years we’ve been doing everything we can to remove ourselves from the food system and I think it’s fundamental for us to be surrounded by plants.”

Not only is it beneficial to our wellbeing, as any gardener knows, he says: “the most destructive thing we do is create food”. The modern food system relies on a huge amount of fertiliser and transporting food crazy distances creates emissions. 

As an antidote, Bakker says it’s possible to live in a complete ecosystem where we grow most of our own food.

“Water, sunlight and nutrients from waste, they all exist in the home.”

The rooftop garden is literally the foundation

Central to any of Bakker’s projects is the rooftop garden, which also doubles as a foundation to weigh down the structure.

“We weren’t allowed to put windows or cladding in before the roof otherwise it blows away.”

By reverse engineering the design to use the weight of the roof to keep the structure in place, no money or resources are wasted on a base foundation. He says this makes rooftop gardens more affordable, as they are often considered as an afterthought and subsequently abandoned due to budget constraints.

We’ve got all the tech already

Outside a few innovative pieces of technology, such as the aquaponics system and charcoal tank that filters water, the home is run off 100 per cent renewables using familiar technologies and practices.

The passively oriented, airtight design with double glazed windows means it will need little mechanical heating and cooling to keep the home comfortable, according to Stiebel Eltron Victorian account manager Sam Frost.

The heat pump manufacturer is supplying hot water, heating and ventilation for the project. The best option was a combined system for hydronic heating and cooling as well as hot water, which Frost says is the size of a single door fridge.

He says it’s a premium product at about $15,000 but ideal for inner city sites where space is tight.

The company also provided a decentralised heat recovery ventilation system with high performance filters for superior air quality. Frost says this is one of the company’s standard offerings, costing between $2500-3000.

The low energy heating, cooling and hot water systems are run using 20kW solar panels, Fronius Primo solar inverters and a Selectronic battery, allowing the home to operate completely offgrid.

Bakker says it wouldn’t be a particularly hard to replicate and scale the model since it relies on a familiar mix of technologies and sustainable design principles.

Going off-grid

Aside from remote locations, the appetite for off-grid homes seems to have waned as built environment decarbonisation efforts have focused on a smart, responsive grid powered by renewables

But Bakker thinks in the future we will all live off grid because maintaining the grid will become too expensive.

“The electricity system is decentralising, as is the food system.”

There’s the cost of cutting down the trees for new power lines (not good for forests either), transport and the skilled tradespeople to set them up. There’s also the endless pruning of trees surrounding the wires for safety reasons. 

He says this will come up against rapidly dropping prices for solar, batteries and other off-grid technology. It’s unclear, however, if this applies to all building types, with denser housing such as apartments challenging to take off grid.

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  1. I too have concerns that the LVL cross laminated timbers we are advocating in the new high-rise construction can’t be reused like steel beams after deconstruction… or recycled into new steel using ~60% recycled waste materials. The resins and adhesives used to create these pine structures can only be burnt in waste to energy, lower down the waste hierarchy, as the timber complements can’t even be mulched (down cycled) or used in other chemical processes to upcycle into more valuable materials.
    we have to consider the full life cycle and energy / carbon cost of these construction processes as well as speed of construction as reduced prelims will drive down project costs and always be chosen over more expensive systems of construction in the main stream.