Rebuilding better
One of our biggest construction polluters is aiming high to reduce the waste mountain.
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-forprofit 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 wasteminimisation 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.”