If you’ve got a renovation planned, or you’re doing a bit of DIY, you may be trying to weigh up which products are a better bet for the planet. As more of us join the hunt for greener options, questions are looming larger about the environmental effects of the materials we use to build our homes.

Dr Emina Kristina Petrović, senior lecturer in sustainability in design at Te Kura Waihanga—the Wellington School of Architecture, thinks the building industry has a long way to go when it comes to providing answers.

Construction accounts for a large amount of the raw materials the world consumes each year—from the tonnes of sand and gravel used to make concrete to the millions of trees milled for timber, she says.

A lot of these materials end up being dumped. “In many parts of the world, about 50 percent of landfill waste is from construction and demolition materials. By volume, it’s a big problem—and it’s made worse when the material contains toxic components.”

The environmental and human health effects of the chemicals used in building materials are the focus of Emina’s research.

“We’ve had a huge increase in the use of synthetic chemicals since World War II and this use is continuing to grow. But in many cases, we know little about the effects of these chemicals, particularly when they’re used in our homes.”

Too many building products make it onto the market without sufficient testing, she says, and getting products pulled when a problem emerges is a drawn-out process.

“There needs to be a very solid indication that something is a problem before anyone starts doing the research. Only once it has been proven to be a problem, through multiple studies, does the process of elimination begin. There’s often a 20- to 30-year time lag between early indications and actually removing a problem product from the market.”

She gives the example of polyvinyl chloride (PVC), which is widely used and promoted as readily available and cheap.

The construction industry accounts for more than half the world’s consumption—mostly in piping, wire coating, and vinyl flooring—and it’s hard to find a building today that doesn’t use PVC, Emina says.

“Any way you look at PVC, there’s something bad. It’s a polymer of a toxic chemical—vinyl chloride. The manufacturing process is toxic, the plasticisers (softeners) added to it are toxic, as are lead and other heavy metals used as stabilisers.

“Some of these substances are now being phased out but the main ingredient—vinyl chloride—can’t be phased out of PVC.”

Emina is currently co-editing a book, together with University colleagues Dr Fabricio Chicca and Guy Marriage, and Associate Professor Morten Gjerde from the Norwegian University of Science and Technology, bringing together research on a range of building materials and their potential effects, from manufacture to use and final disposal. It’s due to be published in 2023.

“For too long, the world hasn’t been paying enough attention to the adverse effects of building materials. We need to include these effects into consideration of what is sustainable. Otherwise, we’re working with a big gap in knowledge.”