Modern engineering has moved past the idea of conquering nature to working in tandem with it. Ken Lunty believes that begins by learning how to value the natural world within an expanded set of success criteria.
The meeting had dragged on for almost an hour as engineers debated the relocation of an electrical pole. Every option was carefully weighed before a choice was made. Then the conversation turned to a mature street tree.
“The decision to remove it came surprisingly quickly,” recalls Ken Lunty, APAC Discipline Lead for Sustainability with Arcadis. “I thought, ‘Hang on. The tree has value too. If we could put a dollar value on that tree, would it change the decision?’”
Research has quantified the role of trees in cooling cities, storing carbon, managing stormwater, improving air quality and supporting biodiversity. Economists have linked tree-lined streets with higher surrounding property values, and the City of Melbourne has developed a methodology that assigns financial value to trees by accounting for their amenity, ecological services, replacement cost and establishment cost.
“When we can show that a tree isn’t worth zero dollars, then everyone at the table can talk the same language,” Lunty said. Engineering has always weighed competing priorities, “nature needs a place on the scales”.
Lunty’s anecdote illustrates a mindset that has shaped more than $150 billion of infrastructure projects, helped refine the Infrastructure Sustainability (IS) Rating Scheme, trained more than 500 practitioners and recently earned him the IS Council’s Enduring Impact Award.
It also reflects a growing realisation that nature has intrinsic value. Around half of Australia’s gross domestic product depends on nature.
Uniqueness and extinction
Australia supports up to 700,000 native species, many of them found nowhere else on the planet. But the natural world is retreating as rapid urban development, overconsumption, pollution and climate change alter our ecosystems. The 2021 State of the Environment Report found Australia has lost more mammal species to extinction than any other continent. These numbers can’t be ignored.
Growing up in Hong Kong, Lunty was fascinated by the relationship between cities and the natural world.
“On the surface, Hong Kong is very metropolitan. But there’s actually a lot of nature among the city, and I wanted to do something to protect it.”
After studying marine science in Canada, Lunty moved to Australia to complete a Master’s degree in environmental management. Along the way, he realised that understanding ecosystems was only half of his challenge.
“If you really want to change a system, you have to understand people,” he said.
Lunty spent 15 years developing his technical skills and building one of Australia’s first sustainability consultancies before taking up his role with Arcadis five years ago. “I didn’t want to see sustainability sitting on the sidelines.”
His goal wasn’t to change engineers, but to change the information they have when they make decisions.
“Most people do the right thing,” he said. “They have nice gardens, compost and don’t waste water. But when engineers go to work, they are laser-focused on cost, risk and program. Is it cost-effective? Is it safe? Is it constructible? These are the classic engineering success criteria.
“It’s not that engineers don’t value nature. It’s that engineering has struggled to value nature in the same way it values cost, risk and program.”
Biodiversity framework
New frameworks and regulations now require engineers to account for how projects depend on and impact the natural environment.
Globally, the Kunming-Montreal Global Biodiversity Framework, adopted by almost 200 countries in 2022, sets the world’s biodiversity agenda for this decade. Alongside halting species extinction, it commits nations to restore at least 30 per cent of ecosystems by 2030.
The implication is profound. Infrastructure design can’t just minimise environmental harm; it must leave places better than it found them.
In the financial sector, the Taskforce on Nature-related Financial Disclosures (TNFD) is placing biodiversity alongside more traditional business risks. TNFD sector guidance issued in January 2025 for engineering, construction and real estate underscores the importance of analysing nature-related dependencies and impacts during the design stage.
At a national level, Australia’s first National Environmental Protection Agency, launched on 1 July, signals stronger regulatory focus on nature.
For engineers, environmental performance is no longer a planning approval issue, but a core design, delivery and risk management consideration.
And at the project level, industry frameworks such as the Infrastructure Sustainability Rating Scheme and Green Star are translating expectations into design and delivery decisions. The latest update to Green Star Buildings, launched in October 2025, establishes a “Nature Positive Pathway” which will require all buildings to achieve a 10 per cent biodiversity net gain by 2030.
Changing decisions
Understanding how voluntary frameworks and regulation fit together can be “overly complicated”, Lunty admits. “But they are all saying the same thing. Nature has a value. Everything is interconnected. We can’t stick to the traditional constraints or success criteria anymore.”
Ideas only matter if they change decisions. One example is Arcadis’s pavement footprinting metric, which compares the sustainability impact of different pavement designs over their lifecycle, from raw materials and construction through to maintenance and replacement.
Rather than handing the client a sustainability report after the design is complete, the metric adds “the equivalent of a nutritional label” to every pavement option.
“We can show our clients alternative pavements that cost the same over their design life, have a 40 per cent lower carbon footprint, are aligned to government targets, won’t cost more, and will still be durable and safe.” The metric can be extended to nature, he adds.
Another Arcadis innovation is a framework which measures biodiversity net gain on every project. This allows project teams to reduce harm and increase their positive impact on nature in real time, as well as report on their achievements.
Over his career, Lunty has chaired technical working groups, helped shape sustainability rating tools and amassed dozens of IS ratings. Yet he believes the hardest part of sustainable engineering isn’t technical.
“Technical output holds so much value in engineering that it is easy to forget to communicate the value of that technical output. At Arcadis we bring our clients and our peers on the journey instead of just saying, ‘Here’s the answer.’” Sustainable engineering succeeds when it appeals to the purse strings and the heart strings.
Change in infrastructure is measured in decades, not months. Yet incremental change is evident. Just one proof point: the 29 projects the IS Council certified in the 2025 financial year avoided almost 3.5 million t of carbon emissions and generated more than $1.27 billion in avoided costs.
“If I look back on the last 20 years, we have made progress. Sometimes it feels slow. But I do have optimism that we are going to get to a point where we’re designing-nature positive.”
The next generation
At a recent Women in STEM event, a Year 9 student pulled out her phone to show him a photograph of a wildlife bridge in the United States. “She said, ‘This is what I want to design when I’m older.’ I told her we already have those in Australia, and her eyes lit up.”
For Lunty, this was another source of optimism. The next generation cares about safety, cost and constructability. But they also expect infrastructure to restore habitats, strengthen communities and leave places better than they found them.
Perhaps that’s what seeing the forest for the trees really means. The better we understand the value of each tree, the better decisions we make about the forest.
