While the global industry’s collective focus firmly points to net zero emissions, what does that mean in practice, particularly for a building? And what’s the potential of adaptive re-uses – and architectural structures that are easy to repurpose – in advancing towards that environmental horizon? Ruth McKenzie, a registered architect in both NSW and Ireland, specialises in sustainable commercial fit-outs and small scale residential projects across a broad range of typologies. As well as heading up North by North Interior Architecture – which she established in early 2020 – Ruth has also worked as a design journalist for national newspapers.

With a Masters in Sustainability from the University of Sydney and particular interest in the adaptation of existing buildings, there is nobody better placed to talk about sustainability in the context of modern commercial spaces, and the path towards zero net emissions. Although, as it turns out, the definition of net zero emissions in the context of a building isn’t clearly nor precisely defined.

“Everybody has gone off and made their own definitions about what they think a net zero building is,” Ruth calls out. “You could say that a net zero energy building is a building with net zero energy consumption. But then you could also say it's a zero carbon building, which means that the building uses renewable sources of energy, that it's designed to encompass its whole carbon lifecycle; that its materials are carefully chosen, and that its end of life cycle is carefully considered. With so many different organisations working in this space, and every country in the world invested in what zero energy is, it’s really difficult to provide a clear definition.”

Between the different energy rating systems, different legislations surrounding it - and the fact that some of it is necessary, while some of it is voluntary - working towards net zero comes with its challenges. “It’s almost like a maze of how to deliver something,” Ruth laughs. So what are some of the things we can do now in order to achieve net zero carbon in buildings?

“First and foremost, you design more efficient buildings, look at some of those circular economy principles, consider how to reuse existing material and design new buildings to be reusable and utilise renewable energies, and low carbon materials,” Ruth lists. But she also adds that sometimes the best thing to do is to build nothing. “Build clever and as little as possible,” she says. “Refurbish and repurpose; utilise prefabrication where you can, and choose low carbon materials and materials that can be taken down and reused.”

Ruth adds that reducing waste is paramount, too. “Construction creates so much waste  – especially when we look at how many buildings are demolished, just to be replaced by something new. There's an argument that says  it's much cheaper and efficient to demolish and build. But is that the best approach?”

Ruth points to Sydney’s CBD as an example. Filled with stunning – and expensive – skry-rise office buildings, NSW capital’s business district turned into a ghost town in the wake of the pandemic. Now, with people working from a myriad of different locations - including homes, cafes and working clubs - these purpose-built edifices run the risk of being underutilised. “What could these buildings become? Could they become something that has a multitude of uses, particularly taking into account Sydney's massive housing affordability issue? What if it was just an integrated mix of housing and office space?”

However, repurposing buildings isn’t as straightforward - and re-use might not always be the best option from an environmental point of view either. It's a balance of factors, considered on a case-by-case basis. “Let’s say you have a tall building and have to replace the glazing. There are considerations around the embodied energy of that, and the kind of environment it provides at present. There's no real right answer,” says Ruth when asked if an increase of adaptive reuse could be a way to achieve net zero buildings quicker.

While there may not be a straight way forward, there certainly is merit in looking at existing structures more attentively before taking them down. “I think that maybe the first step in assessing whether you need a new building is to have a feasibility study. Can I reuse and adapt what I have?” But there is of course more to it, and – according to Ruth – this commitment to reducing carbon emissions needs to come from, and be clearly defined by, the legislation. “It needs to be mandated in that way,” says Ruth. “And once you have that framework, that kind of enables the design team to work together to deliver something that would stand for generations.”

Find out what else Ruth McKenzie had to say by listening to the full podcast here