Our current average house is compounding global overheating with excessive, long-lasting emissions. Lindsay Wood looks at how we could make our housing more climate-friendly. 

Comment: Whichever way we look, the construction sector is spiked onto the horns of nasty dilemmas.

In spite of housing affordability being in crisis mode, construction prices soar at eye-watering rates; greenfield subdivisions continue to gobble up precious land, worsening resource depletion, emissions, and infrastructure issues.

And while Covid-19 hasn’t prevented a crazy building boom, it has contributed to unprecedented bottlenecks in supply chains (see Sam Sachdeva’s Newsroom article Years more supply chain pain for construction).

Then there’s the invisible construction elephant in the room, the totally untenable carbon footprint of our present building practices.

“Few sectors have yet felt the heat on climate strategies the way agriculture has,” I wrote when commenting on the July tractor protests. One such sector is where I’ve spent most of my career – the construction industry.

To illustrate the difference, ask cockies what the climate impact of dry matter is, and they’ll likely say “1kg feed in equals 22g methane out”. Ask a chippy (or an architect, building inspector, or developer) what the climate impact of concrete is, and they’ll likely say “I haven’t a clue”. 

And yet buildings in New Zealand are responsible for similar greenhouse gas emissions to dairy (some 20 percent of the national total), but are growing much faster, and are more intractable to change. Plus, unlike agricultural methane, construction emissions aren’t mired in controversy.

The Building Research Association of New Zealand (BRANZ) has conducted globally acclaimed research into carbon budgets for housing (A carbon budget for New Zealand houses), and its stark message points to the mind-boggling shift needed from what we do now to what we must do.

Over its life, a typical house built today will cause emissions equivalent to some 250 tonnes of carbon dioxide, or about seven times the 35-tonne budget BRANZ computes as compatible with our Zero Carbon Act (for limiting global overheating to 1.5°C).

Housing carbon footprints from BRANZ ‘A carbon budget for New Zealand houses’. Green is construction, blue and red are emissions from running houses over their lives. 

Got that? Seven times over budget! If a designer or builder blew a client’s financial budget seven times over, they’d end up in court, but our current average house is compounding global overheating with excessive, long-lasting emissions of that magnitude.

Indeed, most houses that BRANZ studied blew their entire 90-year carbon budget twice over just in construction, and without anyone even living in them (green).

“It is imperative to close this gap,” BRANZ highlights, “applying this knowledge to mainstream construction as soon as possible.”

So what has to give?

Well, heaps, obviously, in our heads, in our designs, and on the ground.

When interviewed on supply chains by Sam Sachdeva, Building Industry Federation’s CEO Julien Leys noted “construction companies and builders needed to get better at thinking ahead”. And that wasn’t even factoring in the gargantuan challenge of decarbonisation. Which illustrates well his own point about needing to get better at thinking ahead – much better.

Nonetheless, if we do it right, we can achieve a remarkable carbon transformation, have lovely homes to boot, and also alleviate many of the issues facing the sector.

The Scion research building in Rotorua – zero embodied carbon and low operational emissions. Photo: Supplied 

In this sense, “doing it right” will involve minimising emissions in two broad areas: the initial “embodied carbon” associated with actually constructing the building (we can, and should, target “carbon negative” buildings that remove more carbon than they emit), and “operational carbon”, resulting from the building’s use and maintenance. Which in turn will mean significantly smaller homes with lower energy consumption; seizing every chance to replace high-emissions steel, concrete and aluminium with carbon-storing timber; and greatly expanding the reuse of materials.

And the more we succeed in decarbonising our energy supply, the more we need to prioritise slashing embodied (construction) emissions, with climate benefits that will come faster and with more certainty.

Overall we could do worse than adopt Ernst Schumacher’s classic mantra “small is beautiful”. “Any intelligent fool can make things bigger, more complex, and more violent,” he wrote. “It takes a touch of genius and a lot of courage to move in the opposite direction.” But move that way we must.

Which throws a massive gauntlet down before our construction sector, and begs the question ‘Who should pick it up?’

Who indeed? Housing doesn’t sit isolated from the rest of society, and a systems-thinking approach is essential: we live at the ends of roads and drains and electricity grids; occupants of houses spend hours in, and adding to, commuter congestion; and increasing numbers of us sweat over daunting rents or crippling mortgages. So the likes of planners, financiers and transport engineers are clearly in the systems-thinking mix.

But here we’ll focus just on the buildings themselves, which means focusing on an intractable industry that shows little inclination to bootstrap itself up on this critical decarbonisation mission.

As well as the important work going on at BRANZ, the Government has just announced cross-party support for serious urban intensification plus the exciting emissions-focused Ngā Kāinga Anamata community project, the Ministry of Business Innovation and Employment (MBIE) is developing a raft of initiatives, and private organisations like the New Zealand Green Building Council are active in this space.

However, for the speediest responses – and do we need speed – we should pressure the “mainstream construction” to which BRANZ refers, such as group builders, retirement villages, and Kainga Ora which, together, instigate some 90 percent of new dwellings. Kainga Ora already has its useful Sustainability Framework, operates under government protocols, and is driving Ngā Kāinga Anamata, so what of the others?

The builders of mainstream housing and retirement villages play a major role in moulding (and limiting) public expectations, but they show few signs of shouldering responsibility to transform the way they – and we – build, or of propelling the rapid carbon reduction journey that is so essential.

There’s a wide sweep of strategies they might adopt, such as moving from an emphasis on spaciousness to one on beautifully-crafted compact design; and from an abundance of high-emissions products like ceramic tiles, concrete, and expansive engineered kitchens, to a Scandinavian-type delight in modesty and the simple use of natural materials.

When writing on farmers, I noted they have historically been applauded for doing things they must now abandon. Homeowners, designers, and builders now face a similarly daunting transition, one that turns yesterday’s award-winners into tomorrow’s villains. But again, like farming, while this will mean a tough transition, it can still end up in a good place.

And it can bring unexpected wins, “co-benefits”, along the way. For example, significant downsizing is right in sync with quests for affordability and intensification; and favouring renewable local products like timber helps slow our appalling rate of resource depletion while making us less dependent on struggling international supply chains.

Picking up on yesterday’s winners being today’s villains, building designers have a major part to play, and must make a major shift to do so. We (yes, I’m one) must unlearn much of the “bigger, flashier, different” aspirations that are so beloved by glossy mags and awards judges, and that we in turn promulgate with our clients.

We must refine our space planning skills even further, become more fluent in the climate properties of materials and in thermal design, and assemble a toolbox to help explain the delights of “less” to clients who have grown up in an era expecting “more”. And learning to design for a circular economy will significantly ease issues around supply lines and waste streams.

Regulators don’t escape either. Before long, MBIE will issue emissions reduction controls for the building sector, but we also need regulations that are more amenable to innovation and to the widespread reuse of materials. And these quickly point to the need for demo-yards-on-steroids, to greatly expanded upstream and downstream value chains capable of receiving a huge array of deconstructed products, then reconditioning and channeling them back into complying new buildings.

Which returns us to Sam Sachdeva’s article. Although not written about decarbonisation, it repeatedly points to the benefits of building with locally-sourced materials. For example, Dean Kimpton, of the Construction Sector Accord, in it framed the need to “manage down” international factors outside our control, and Sachdeva reports respondents to an industry survey favouring more local manufacturing. Of course timber ticks many boxes in those arenas.

Kimpton’s summary of the supply chain issue also encapsulated the decarbonisation challenge. “There’s a new normal now,” he said, “and we’ve got to figure this one out”.

So true. And he wasn’t even considering slashing emissions 85 percent. So let’s hit turbo mode on “genius and courage”, and get moving on this crucial “new normal”.

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