29.01.19

Constructing our circular economy

By Andy Kenworthy

Anyone who’s ever been on a building site notices how much gets thrown away. Nearly every project starts with some form of demolition or clearance. There’s earth moving, removal of unwanted buildings and infrastructure, as well as discarded fittings and fixtures. 

Some waste is inevitable. Old materials may break while being deconstructed. Even the most experienced professionals can’t be exact about the materials they will need. Most of it comes in standard sizes and packages that rarely completely match requirements.

Some materials fail. Packaging accumulates. There are also the more obvious mistakes. Materials left out to spoil. Tools and materials destroyed by misuse. Ordering the wrong stuff and never getting round to sending it back.

There are the myriad of new disposable bits of kit. Collated screw packs, nail-gun cartridge strips, tubes, sachets and other innovations speed up the work, but add to the rubbish.

Some of this waste is hard to deal with. Cement and glue encrusted packages, paint splattered tins – they can all be hard to separate, even if time is available. Some of it is toxic.

Traditionally, labour costs have formed a high proportion of overall costs in construction. This has helped drive a mentality that there isn’t time to take the care to keep waste to a minimum. I remember my teenage summer job in the late 1980s. I cleaned up after tradies who were constructing blocks of flats. Everything got piled two stories high and then landfilled. Thankfully, the sites I see nowadays are somewhat different. Health and safety considerations and cost calculations have moved on. Material and landfill prices are rising. There’s more incentive to cut waste and deal with it more appropriately.

But construction and demolition waste still represents around half of what’s going into New Zealand’s landfills. The recent building boom and population pressure will do nothing to stem this flow.

A recent AUT study found that in the construction of an average Auckland house selling for $828,000, $100,000 is wasted. This includes $31,000 of materials. It includes labour inefficiencies like repeating incorrect work.

Think of the margins savvy construction firms could open up if they get that sorted!

An average of 2,000kg of timber waste and 700kg of plasterboard waste occurs in a typical house build. And typically ten percent of ordered building materials are wasted.

The circular solution

So how can we fix this, and cut the huge cost to our economy and environment? The circular economy provides an approach that could eliminate it almost completely. In a circular economy the lifecycles of all materials are maximised. Their use is optimised. At the end of life all materials are reused.

One of the first steps towards installing this new way of working is to create innovations to deal with the more problematic construction materials. For example, much of the construction timber we use must is chemically treated. This severely limits reuse of offcuts and deconstructed timber. We need to consider different approaches in cases like this. The circular economy mode of design can help drive the innovations we need.

There are simple ways to take up this challenge on the ground right now. We can use of services like Green Gorilla. The company has its own construction waste materials recycling facility.

Diversion services are offered by the likes of Junk Run and Trow Group. They re-distribute materials to communities instead of into landfill. The more we use them, the more effective and efficient they can be.

Regulation may be another way of driving this change. We need to increase the Waste Levy to make it less cost effective to simply bury our lack of care in a hole.

Better information about product disposal would help too. We need clear labelling stating whether materials can be recycled, and how.

Product Stewardship schemes need to be more widely adopted. A number of Ministry for the Environment-accredited Product Stewardship schemes already operate within the construction sector. Over a quarter of a million tonnes of waste concrete is generated in New Zealand each year. Envirocon turns wet waste concrete into a modular wall system called Interbloc.

Resene’s Paintwise scheme recovers unwanted paint and paint packaging. The Interface Re-entry programme converts old carpet to new carpet. We need more of this.

But ultimately we may need to fundamentally change the way we design and build. A major challenge in minimising construction waste is getting resources on and off sites efficiently. Prefabricating modular housing centrally may be one way ahead.

Innovation wanted

We are in a resource constrained world. We live in a relatively remote country. We are struggling to provide quality housing for a growing population. We simply can’t afford to keep building in the way that we currently do.

Construction companies that take on this challenge early will have a huge competitive advantage on those that lag behind. And Kiwis who lead innovations in this area may find themselves in demand all over the world.

First appeared in NZ Business Magazine