A European report imagines a world where galvanized steel structures are part of a circular economy. Australia is much closer to living there.
For structures with multiple assembling and dismantling cycles, galvanized steel solutions are recommended, as they result in a life cycle cost benefit of $35,000 and a CO2 saving of 98 tonnes in the reused lifecycle. This research is highlighted in Galvanized Steel and Sustainable Construction: Solutions for a Circular Economy, a report by the European General Galvanizers Association (EGGA) that the Galvanizers Association of Australia (GAA) has recently made available.
This way of thinking about building – anticipating the multiple life cycles that structures, components and materials can have – is central to the circular construction trend. As outlined in a previous article, it’s captured by a five step process: make, use, reuse, remake, and recycle. Galvanized steel shines in all five steps (as seen in the below graphic) but its ability to be moved and reused is particularly impressive.
Move and reuse
Designing galvanized steel structures that are standardised and modular, with bolted connections that enhance the prospects of reuse while also increasing the size of structures that can be hot dip galvanized, is an approach some Australian companies have been taking for years.
“A lot of our sheds – maybe 80 per cent – are also roof lifted,” says David Green, Operations Manager at Entegra Signature Structures. “This is where the roof is built on the ground and cranes lift it, with the columns dangling beside it, and you bolt them up. So it’s very quick to erect and safer in many ways because you’re not working at heights.”
Green says while obviously there is rarely an intention to remove the structures once they’re in place, their design makes it effective to do so should the need arise.
He offers a recent example, where a sports canopy constructed at a high school was able to be unbolted and moved to another location. Even more impressively, years ago the company built an aircraft hanger in kit form locally that was then sent across the Southern Ocean on a boat to be built on Davis Base in Antarctica.
The major alternative to hot dip galvanizing is using a painting system to coat steel, but this adds cost, time and carbon should a structure get reused. Because it’s highly likely that any significant shift to the structure will result in some kind of scrape or other rudimentary damage to the surface of the components that requires new painting.
“Galvanizing being a sacrificial coating, if it gets knocked it’s usually not a big issue, since it’s the zinc forming an oxide that prevents corrosion,” says Green. “Paint requires 100 per cent coating. As soon as you have chipped it and you have bare metal it’s compromised.”
Of course, the ultimate sign of whether something can be used is its initial durability. And it’s here that galvanizing excels, says Green. Entegra recently took orders on galvanized steel sheds for New Zealand and were required to give assurances on the design life.
“I took into account a worst case scenario in terms of where a structure was located – volcanic, close to the coast and so on – to do those calculations,” says Green. “What I came up with is about a 150 year design life. If I’d done the same calculation for somewhere miles from the coast and not a lot of moisture, you can imagine the structure could be here for thousands of years.”
Of course, it’s not just Entegra that is designing durable galvanized structures that can be reused.
“In Australia, reuse of steel components and products is increasing, with some people now recognising that refurbishing items – by having them regalvanized – extends their life far beyond their initial design,” says Peter Golding, CEO of GAA.
Boat trailers and small industrial pieces are commonly regalvanized today, says Golding, but the opportunity for the reuse of items such as guard rails and even whole buildings is growing.
“Legal standards when it comes to the traceability of steel have improved, so engineers and other experts can be more certain that products remain fit for purpose. Verified steel also means that – excluding fatigue loaded structures – engineers can be confident in the ability of products to perform in a reuse phase.”
To get a better idea of how galvanized steel can help your firm achieve circular construction, you can download the EGGA report from the GAA website.