Developers and designers looking for supplementary ways to net zero targets should focus on an overlooked source of emissions right in front of them: rework.

Unlike other more quantifiable sources of emissions, the carbon cost of rework is difficult to estimate due to unpredictability and a web of supply chain factors. Nonetheless, for businesses committed to realizing a sustainable future, rework is an avenue of unknown risks – and opportunity – they cannot afford to ignore.

To understand how rework impacts the environment, it’s essential to grasp its connection with embodied carbon. The latter describes the totality of carbon emissions produced throughout a building’s entire lifecycle, which encompasses manufacturing, transportation, construction, demolition, and disposal of all construction materials utilized. Recent KPMG research identifies embodied carbon as 22% of an asset's overall carbon emissions, positioning it as a sizable new frontier for carbon mitigation efforts.

As a building undergoes repair and rework, its embodied carbon footprint can multiply by varying degrees as initial material is torn down and replaced with new construction. The more extensive the rework, the greater the end ecological cost.

Rising demand for built-to-rent housing and urban infrastructure could increase the amount of embodied carbon waste generated via rework – crippling both corporate and national net zero ambitions if left unchecked and unaddressed in the present.

Paying the price on two fronts

What is the far-reaching cost of rework, for both the industry and the natural environment? Its financial ramifications are well documented: a 2018 study by Queensland’s Bond University estimated that rework consumed 34% of construction budgets, eroding mean yearly profit by a staggering 28%.

The Strata Community Association of NSW recently reported that owner corporations had to allocate over $79 million to address serious defects between 2016 – 2022, with an average cost of $283,000 per building.

 In the coming years, a combination of rising national inflation, stricter construction standards, and growing demand for materials will culminate in more restrictive end construction costs, and subsequently, a higher price tag for rework.

The ecological impact of rework is a lot more opaque. Up to 80% of a building’s embodied carbon footprint comes from materials during construction, but that percentage will rise due to rework events – which can vary depending on the scope and scale of repairs.

Certain materials, like cement and aluminium, have a higher percentage of embodied carbon compared to others like plasterboard or tiles, adding complexity to efforts to tabulate the carbon cost of rework.

Maybe the focus shouldn't solely be on evaluating the environmental impact of rework. The aim should instead be to minimize the occurrence of rework altogether. The construction sector currently constitutes 18.1% of Australia’s carbon footprint and is bound to face increasing scrutiny from both the public and government regarding its efforts – or lack thereof – to achieve net zero targets.

Focusing on reducing rework as a major source of embodied carbon emissions signals that Australia’s developers remain committed to realizing climate goals and ensuring the safety of future generations. Fortunately, they can do so proactively by using several new and innovative methods.

Reworking how we approach construction

Numerous factors, like bad planning, design errors, and communication breakdowns, contribute to the necessity for rework. Additionally, conventional construction methods could also lead to onsite material damage and improper installation, further exacerbating the need for rework. By embracing a variety of modern solutions, developers and designers can mitigate these issues and reduce the risk of rework in their projects.

Prefabrication is emerging as an effective solution for modern construction needs, due to a precise manufacturing process that reduces errors and minimizes waste and emissions. Studies have found that prefabrication creates 45% less carbon than conventional onsite construction for residential buildings, with even significantly greater reductions for large-scale projects.

Prefabricated or modular materials are also more conveniently recycled or upcycled, further reducing embodied emissions, and contributing toward a more circular economy.

Developers and designers can even plan to reduce the risk of rework on the drawing board using Digital Twins. The technology demonstrated tangible benefits in projects such as Queen’s Wharf Brisbane and the Port of Melbourne’s Rail Transformation Project, where it facilitated high-precision planning that resulted in more efficient construction and a sharp reduction in waste and rework.

And the benefits of digital twins extend far beyond the construction phase. The NSW government recently completed a digital map of over 500,000 buildings in Western Sydney, which could facilitate future urban planning and development, streamline asset management, and reduce the likelihood of large-scale rework due to oversight and lack of visibility of the existing built environment.

It's time for the construction industry to view rework not just as a post-construction event, but also as an avenue to further reduce emissions and their impact on the environment.

That may require a radical rethink of how we plan and conduct construction, but recent years have shown that industry players can adapt graciously with the times. And that shift is overdue; we must act now to curb the impact of rework and embodied carbon on future generations.

By Niall McSweeney, President, Cost & Project Management, Asia Pacific at Altus Group

Image: Digital Twin technology demonstrated tangible benefits in projects such as Queen’s Wharf Brisbane. / Graphisoft.