As one of the world’s oldest man-made building products, the humble brick has a long story to tell, complicated recently by a manufacturing process which lumps it in with other hard-to-abate industries like steel, aluminium and shipping.

Clay bricks are naturally energy-efficient products, absorbing heat, storing it and releasing it later into the environment.

While this saves lifetime greenhouse gas (GHG) emissions by reducing demand for artificial warming and cooling in homes, the process of firing bricks to more than 1000 degrees Celsius in kilns powered by fossil fuels uses a lot of energy.

In the early 2000s, the nation’s leading brickmaker, Brickworks, started a serious program to address its energy and labour-intensity – and a safety record which demanded improvement – by consolidating sites and investing in new equipment.

It was the antecedent of today’s sustainability mission, with $400m-plus spent since 2006 on fuel-efficient production processes, operational improvements and carbon reduction measures.

Over the same period, the company says it has eliminated 56 per cent of its Scope 1 and Scope 2 emissions – direct emissions controlled by the company and indirect emissions from the use of purchased energy.

“I’d love to sit here and say we cut back on our energy usage in the early 2000s to improve our sustainability, but really it was to drive our costs down so we could remain a competitive building product,” Brickworks chief executive Mark Ellenor said.

“Because, you know, what other product gives you a 100-year warranty? Yes, there’s some embodied carbon upfront, but the life span of bricks for housing is better than any other building material on the planet.

“And we obviously had some spin-off benefits (from the investment program) once it became an imperative to decarbonise.”

Brickwork’s progress on cutting emissions has been underpinned by redesigned products, greater recycling of materials, use of renewable bioenergy such as sawdust and landfill gas in some of its kilns, and investment in modern, fuel-efficient production processes.

In Victoria alone, the company downsized from five factories to one while maintaining its annual output of about 180 million bricks.

Critically, however, energy usage was halved, according to Mr Ellenor.

Lost time for injuries was slashed, as well, after Brickworks declared in the early 2000s that the first person to actually touch one of its bricks should be the on-site bricklayer.

It spelt the end of all the unnecessary handling as the raw product progressed from the quarry to loading on the delivery truck.

The introduction of renewable bioenergy helped to pare back the embodied carbon, with biofuels accounting for 11% of the company’s energy mix in the 2023 financial year.

In 2013, Brickworks’ Austral Bricks division in Tasmania was recognised under the Climate Active Production Certification program for producing the nation’s first carbon neutral brick by using sawdust waste from the state’s pine plantations as a fuel to fire its kilns.

Sawdust, according to the company, is categorised as biomass – a biological material derived from living or recently-living organisms which produces a more sustainable manufacturing process than any fossil fuel.

The remaining emissions from the Tasmanian operation are offset through the purchase of units in various certified projects such as tree-planting.

The success of the investment program inspired sufficient confidence in 2023 for Brickworks to announce a new carbon target – a 15 per cent reduction in Scope 1 and Scope 2 greenhouse gas emissions by 2030, from a 2022 baseline.

Contributions to the new target are likely to come from other projects like tapping landfill gas and anaerobic digestion, a process which displaces natural gas by converting organic waste into renewable gas, in the absence of oxygen.

Brickworks says combustion of landfill gas emits 10 times less carbon than natural gas.

It’s no surprise, therefore, that the brickmaker is already consuming biogas produced by dry waste – collected from construction sites and businesses across Sydney – at two of its western Sydney brick plants, including since 2013 its biggest Australian brick plant at Horsley Park.

The company is also conducting a feasibility study at the same location to generate biomethane by compacting Sydney’s food waste in digestive tanks.

The role of the digesters is to capture methane and carbon dioxide so they don’t escape into the atmosphere.

Biogas and biomethane are considered to be renewable because they’re produced from organic matter like food and agricultural waste, which will be generated in perpetuity.

However, there is a lively debate about their contribution to the climate transition because they are not 100 per cent greenhouse gas-free.

Advocates, on the other hand, say that biomethane does not increase the concentration of GHGs because carbon dioxide and other gases that contribute to climate change are released into the atmosphere anyway during the decomposition process of organic matter.

The Australian Renewable Energy Agency has said that biogas production and usage can contribute to emissions reduction by providing a renewable energy source and capturing emissions from animal waste storage and landfill sites which would otherwise be released into the atmosphere.

Mr Ellenor said the biomethane feasibility study at Horsley Park could potentially lead to a $60m-$70m project.

“We could then look at rolling out more of them at some of our other plants,” he said.

“It could halve our gas usage and the waste management company gets a tick because the food waste doesn’t go into landfill.”

Despite Brickworks’ progress on decarbonisation, Mr Ellenor said he was reluctant to set a net-zero target date.

“With offsets I could get there, 100 per cent, but I’d like to generate my own offsets in Australia and New Zealand,” he said.

“We offer a carbon neutral brick out of our plant in Tasmania but unfortunately we don’t have access to (sawdust) right up the east coast, and the kilns have become much, much larger so it wasn’t feasible when we looked at it.

“I want to decarbonise, but I also want to get some of this landfill gas and anaerobic digestion going through the factories, because it will make us comparable to any imported product.

“If the technology is there and it works, we can then start thinking about setting some longer-term goals.”

The information contained in this article is based upon sources believed to be reliable but which have not been independently verified. Opinions or ideas expressed may not necessarily be those of National Australia Bank Limited (NAB) nor may they necessarily reflect NAB’s views or endorsement. This article is for informational purposes only.