Every day in New Zealand, 17,000 tonnes of construction and demolition waste is dumped into landfills. That’s up to twice the tonnage the general public produces as household waste, according to the Building Research Association of New Zealand (Branz).
While politicians and the public wring their hands about plastic drinking straws, single-use bags and fruit labels, Branz says the construction and demolition (C&D) sector is one of the largest waste producers in New Zealand.
It’s a hidden problem, says Mark Roberts, senior waste planning specialist at Auckland Council. About 90% of it could be diverted from landfills for reuse or recycling, but isn’t.
“It’s created on building sites that are fenced off,” says Roberts. “It goes into high-sided skip bins, so you can’t see what’s in there. And then it’s transported to a landfill.”
With little incentive to do otherwise, builders and contractors choose the cheapest skip provider. Inside that skip will be rubble, wood, plastic, metal, plasterboard, insulation, packaging and a range of materials. “If they’re lucky, [the skips] might go to somewhere like Green Gorilla or Waste Management, where it’s sorted,” says Roberts. “The general public don’t go to those places. That’s why the public zeroes in on things like straws and plastic bags and coffee cups.”
International laggard
New Zealand’s scorecard on C&D waste is poor compared with many other developed nations. Waka Kotahi NZ Transport Agency estimated in 2019 that 3.5 million tonnes of C&D waste is generated every year. Data for the diversion of waste is of low accuracy but is estimated at 17% nationwide, according to the Ministry for the Environment. That compares with 87% of C&D waste recycled as a matter of course in Denmark.
Materials that can be diverted remain in circulation for longer, reducing the need for finite natural resources to be extracted.
The country is critically short of landfill sites, which encounter enormous opposition due to concerns over noise and environmental degradation, not to mention the cost and emissions problems of truck movements, associated traffic congestion and wear and tear on roads.
A 2018 Auckland Council report found C&D waste made up 40% of all waste sent to landfills in the region. Outside Auckland, the proportion of the waste mountain made up of C&D waste is nearer 50%. The council aims to reduce total waste going to landfill by 30% by 2027; as the single largest waste stream, C&D is its main target.
Our poor track record is one that the ministry knows it needs to deal with. “Too much rubbish is ending up in landfills and our environment,” says Shaun Lewis, the ministry’s director of waste and resource efficiency. “Much of what we send to landfills could be recycled, composted or reused. Or worse, instead of landfills, waste is ending up in our precious awa [waterways], whenua and moana.”
The squeaky wheel
Sometimes it takes a squeaky wheel to get change under way. At construction firm Naylor Love, that squeaky wheel was quantity surveyor Annette Day.
In her 18 years with the construction company, Day had become uncomfortable about the amount of building waste. “Over the years, I could see what we were doing with waste wasn’t good,” she says. “The general waste management was one bin on site, and everything went into it.”
She started asking questions, making contacts, and encouraging management to do the right thing. Her colleagues argued it had always been that way and always would be.
“Waste minimisation became a passion of mine, and over the past few years, people actually started listening to what I was saying and backing me.”
One of Day’s early wins was encouraging management to switch skip providers from whatever was cheapest to Green Gorilla and Waste Management, which empty skips and sort materials for diversion in processing facilities. It costs mor
e, which was a disincentive for those C&D companies concerned only with their bottom line.
That single move reduced by 80% the amount of C&D waste from Naylor Love construction sites in Auckland, says Day. It wasn’t quite so easy in other parts of the country where opportunities to divert waste are not as developed.
Plastic audit
It was a big step forward, but just a start. Like other construction firms, the company didn’t know what was in its skips up to that point, she says. The bin providers fed statistics back to Day that spelt out the composition of each site’s waste. This enabled Day’s team to begin to look for increasingly efficient ways to minimise waste on site.
A collaboration with Unitec’s engineering department, which carried out a plastic audit of the firm’s build at Onehunga High School in 2021, led to improvements. These included arranging for delivery of soft plastics to sustainable building materials firm Saveboard, in Hamilton, for remanufacturing into fence posts, and sending PVC pipe offcuts back to the manufacturer. Another outcome was switching from single-use plastic wrapping for timber from Mitre10 Mega, to reusable Naylor Love-branded covers. Until then, Mitre 10′s ordering system automatically assumed buyers wanted their timber wrapped. When a box was required to be ticked to get the wrapping, wrapping demand dropped from 90% to 10%.
Another turning point came at a Long Bay project on Auckland’s North Shore, where three truckloads of reusable materials, including insulation, Gib board, timber offcuts and PVC piping, were diverted to not-for-profit home builder Habitat for Humanity.
Day lobbied management to set up on-site waste sor
ting for the company’s next build at AUT’s North Campus in Northcote, where the four-storey A1 building, which will house student support services and informal spaces, is due for completion in 2024.
Management was keen – even if site managers huffed and puffed in the beginning, complaining it was too hard, they didn’t have enough time to sort and it would cost more.
Separation at site
But with the help of a $35,000 waste minimisation grant, Day got her resource centre for sorting waste. The single skip was replaced with multiple labelled bins, bags and receptacles for five types of plastic, cardboard, metal, wood, rubble and other more obscure items such as cable ties.
Day invited Roberts to join her and relocate his desk from Auckland Council’s head office to her portacabin for the duration of the build on site.
When the foundation work started in April last year, the pair waited with bated breath in the resource centre to see what the labourers whose job it was to dump waste would do. Faced with multiple labelled bins, the NZ Labour Hire “resource sorters” mostly figured it out themselves. “They nailed it quickly, and it’s so pleasing,” says Day.
The A1 project is an experiment, and both Day and Roberts do the portacabin version of curtain twitching whenever a worker walks into the resource centre carrying waste. They admit it’s the highlight of their day, watching workers read the signage and make the right choice.
For the sorting centre to work, Day needed to find outlets for the materials. That was relatively easy for wood, rubble and certain numbered plastics. The plastics go back to manufacturers such as Marley, to Saveboard for remanufacturing into board, and Polymer Processing where they will be made into flowerpots. Gib board is processed and turned into fertiliser, and concrete is ground up and used as fill for work such as retaining wall construction.
And the range of outlets for materials is growing fast.
Sometimes, waste minimisation requires tradespeople to change behaviours of a lifetime. For example, Day worked with the flooring contractor after she discovered that the polystyrene supplier for the foundations could take bagged offcuts back provided they were clean, which they weren’t to begin with. Likewise Marley, which provides a product stewardship scheme, needed the PVC pipe offcuts it takes back to be clean, and set up washing stations on site.
Denailing it
When Day and Roberts suggested to the slab contractor for the A1 job that the wooden boxing used to pour concrete should be de-nailed and reused, the initial reaction wasn’t positive. The contractor did the maths, however, and figured out that staff time spent denailing cost less than buying new wood for each job. “If you’re chucking 100 metres [of boxing] out, you have to buy 100 metres new at $6 a metre,” says Day. Denailing was far cheaper, she says.
Waste minimisation is driven by hundreds of micro decisions and actions on site every day, says Day. The mere presence of the resource centre has helped with those and the waste minimisation ethos spread across the site by osmosis. Many subcontractors are becoming noticeably more careful around waste. More take materials away for reuse that might otherwise have been thrown in the skip.
Waste on traditional building sites is eye-watering. Unopened materials often end up in skips on New Zealand building sites, says Day. When one skip was emptied by Unitec sorters at the Onehunga High School build, they found an entire unused roll of floor covering worth $1000. Day never did find out how it got in the skip. “But when I rang the flooring subcontractor, he was very glad to have it back because he would have had to buy another roll to finish the job.”
So far, more than 90% of waste on the A1 build site has been diverted from landfill. The other 10% does need to go into a small, low-sided 4.5 sq m general waste skip, which is under daily scrutiny, says Roberts.
“We delve in and try to find out what it is, where it comes from, why is it there, and what are the options for it? A huge advantage of being there every day is that we see these items appearing.”
They find coffee cups, Coca Cola bottles, lunch and kitchen waste and contaminated waste. Sometimes, subcontractors fly-tip into the bin when no one is around.
Day and Roberts host a steady stream of visitors to their resource centre, including delegations from rival building companies. Day is keen to share her knowledge with the entire industry.
Levy levers
The jury is still out on the economics of the experiment. At the beginning, Day fielded “wild accusations” from site managers that separating the waste was going to cost another three hours a day of labour. That hasn’t proved to be the case, and conversely, there have been unexpected gains. “We’re using more of what we’ve got, and we’re buying leaner,” she says.
The cost to have already sorted bins removed by Green Gorilla or Waste Management is slightly less than a mingled skip. But it is still more than using low-cost skip-to-tip providers who send everything to landfill.
The economics will change, says Roberts. One of the reasons that the cheapest skip usually wins is that the waste levy for dumping is very low by international standards. In Sydney, landfills pass on a A$151.60 ($162)mixed waste levy. Here, the government is phasing in landfill levies and the charge for mixed municipal waste will rise from $50 to $60 a tonne next year. A $20 a tonne charge for C&D waste was introduced last July, and rises to $30 a tonne in July next year.
Another issue here is that few councils require C&D companies to submit mandatory waste management plans before demolishing or building. Both the Hamilton and New Plymouth councils have introduced bylaws for that and other councils are looking to follow suit.
Construction and demolition is included in the government’s Emissions Reduction Plan, says the Ministry for the Environment’s Shaun Lewis. To reduce the amount of waste Aotearoa New Zealand produces, he says, the ministry aims to invest more in waste reduction initiatives and infrastructure, address problems with individual products and strengthen monitoring and compliance, among other measures.
The government’s just-released waste strategy, Te Rautaki Para, sets out its vision to 2050, which involves reducing waste in three phases. The first focuses on circular thinking and mentions the need to develop resource recovery and reprocessing infrastructure.
There are also proposed amendments to the Building Act aimed at reducing waste from design in particular. And Parliament’s environment committee is looking into how to reduce the amount of construction and demolition waste going to landfill. Other changes, expected to be phased in from 2025, will contribute to the goal of reaching net zero carbon by 2050.
Meanwhile, a wide variety of organisations such as the Sustainable Business Network and WasteMINZ are now conducting research and waste reduction programmes.
Nipping it in the bud
For diversion to work better, the circular economy needs to mature. Finding outlets to take recyclable waste can be difficult for small and large builders.
In theory, as more waste is diverted, markets will grow for the recycled or reused materials, making it cost effective for that waste to be sold, says Roberts. That’s how it works in Europe, but it’s not yet economically viable here for many waste streams, partly due to the low dumping fees.
It’s too easy to blame the builder for waste in a project, he says. Manufacturers need to take responsibility for the environmental impact of their products. Developers, designers, architects, specifiers, engineers, quantity surveyors, and landscape designers also contribute to waste, he says.
Design and procurement processes in particular need to reduce built-in waste, says Jeff Seadon, a waste minimisation consultant for a range of international and local government agencies and industry. “The designer builds in waste for aesthetic reasons, the quantity surveyor adds a percentage, typically five to 10%, to make sure there is no shortage on site, and the retailer also adds a wastage factor for the same reason,” he says.
“A recent case study we conducted with [state housing agency] Kāinga Ora showed that 44% of timber delivered to site, not including the pre-nailed framing, ended up in the waste skip.”
The C&D industry knows it needs to do better, says Seadon.
The cost isn’t just to the environment. In a previous role as an academic, he conducted research at AUT, which concluded $31,000 of materials were wasted in the average New Zealand house build. Home buyers foot the bill for that unnecessary waste.
Small gains
It isn’t only large building companies that are taking their carbon footprint seriously. Auckland Council’s senior waste planning specialist, Mark Roberts, has worked with smaller builders who want to make a difference.
One example was builder Nigel Benton, who contacted Roberts and offered to run a skipless build on an eight-townhouse development in Auckland’s New Lynn after reading an article about him in a building magazine.
Despite being tight for space, all waste was sorted on site and diverted from landfill by Junk Run, or picked up by Unitec, which was conducting research into plastic waste.
Benton’s cold call to Roberts led to a collaboration between Auckland Council, Junk Run and Unitec that saw 90% of the waste from the build on Titirangi Rd diverted from landfill.
But for every Benton or Naylor Love (see main story), there is another developer at the bad end of town that does the exact opposite. Roberts has taken journalists to fast-growing Flat Bush in the city’s southeast to see just how bad it can be.
“The building sites in Flat Bush [for example] are eye-wateringly depressing,” he says. “It’s quite horrific out there. Extremely untidy sites. Huge amounts of waste. Just really bad behaviour. There are builders who throw waste on neighbouring properties, into reserves, onto berms. Their waste spills out onto the street.”
Some of the issues come from one-man-band-type operations. “In Flat Bush, the sections are often sold off individually to small developers. If you go to Paerata Rise, or the developments that Fletcher is doing, you won’t see those sorts of issues.”
Rebuilding better
Growing a circular economy is important for both construction and demolition.
Government housing agency Kāinga Ora is in the process of removing thousands of post-war dwellings from sites to replace them with more than 40,000 new homes over the next 20 years.
Despite popular perception, only 7% of those old state houses are relocated for reuse. The ones that are saved go to eligible groups, including Māori, community housing providers, non-governmental organisations and private sector groups with suitable land. The homes are sold for $1 and Kāinga Ora pays towards transport costs for not-for-profit recipients.
Many simply can’t be relocated. Some are two or more storeys high. Others have hazardous materials. In some cases, the homes are so run down it’s not worth spending double the money relocating them, says Rachel Trinder, the agency’s manager of waste minimisation and site clearance.
The next best outcome is deconstruction, with experienced contractors such as Trow Group and Green Way Limited.
Many materials from deconstruction jobs are saleable, says Trinder. “Native timber is valuable, for example. It’s the same for concrete, which can be crushed and reused.”
The contractors report back at the end of the project what materials were cleared from the site, what they managed to divert, and where the materials went. That information helps minimise waste on future projects. “We track and monitor the landfill diversion target.”
The salvage from deconstruction belongs to the contractors doing the work. However, Kāinga Ora has encouraged the two companies to participate in salvage days for the public and supply not-for-profit organisations.
One example of a not-for-profit that benefits is The Re-Creators, based in Auckland, which runs public workshops with used timber and other materials, as well as training in high schools.
By virtue of its size, Kāinga Ora is one of the largest polluters in construction. But it takes its environmental responsibility seriously, says Trinder. In the 2021-22 financial year, it diverted 87% of uncontaminated waste from old state homes removed in Auckland. Its target is 80% diversion of uncontaminated materials by weight in Auckland and Northland, and 60% in all other regions, where markets for C&D waste are smaller. Many of the secondary markets for waste, such as Golden Bay Cement, which burns wood offcuts, lowering its need for coal, are in the top half of the North Island.
The second phase of the agency’s waste-minimisation programme is reducing construction waste. Although at an early stage, its new homes are built to Home Star standards, which require that 70% of C&D waste is diverted from landfill, Trinder points out.
One goal of the programme is to learn, then feed information back to builders and the wider construction industry, she says.
“Ultimately, what we’re wanting here is more [construction companies] to follow suit [and drive] innovation in terms of end markets.”