Natural, but is it better?

Recently I completed a postgraduate sustainability programme at the University of Cambridge. For my final literature review I picked the question I circle around every day while building Elken: are bio-based materials actually more sustainable than conventional ones? Not do they feel better, or sound better. Measurably better, across their whole life, from harvest to skip.

I went in expecting a comfortable yes. Many academic papers and references later, the answer I came away with was more complicated. It was also far more useful, because it changed how I look at every product we use and list on Elken.

Why this question matters

Construction is one of the largest sources of carbon emissions on the planet. Buildings account for around a third of global energy demand and 34 per cent of energy related carbon emissions. For decades the effort went into operational carbon, the energy a building burns once people live in it. Insulate more, heat less. That work is important, but it hides something: roughly half of a building’s lifetime emissions are embodied carbon. That is the carbon cost of the materials themselves. Extracting them, manufacturing them, moving them, maintaining them and one day disposing of them.

That half is where material choice lives. It is why what your walls, floors and surfaces are made of matters as much as how you heat the room.

The case for natural materials is real

Materials that grow, like timber, hemp, straw and cork, do something concrete and steel never can: they pull carbon out of the air while they grow and hold onto it once they are built into a home. The research here is striking. Studies of engineered timber structures show embodied carbon reductions of up to 70 per cent compared with conventional construction. Fast growing plants like hemp and straw are especially interesting because they regrow in a season rather than a lifetime, so they absorb carbon far faster than a forest does.

And none of this is new. Humans built with these materials for most of our history. Concrete, steel and glass took over because they were cheaper at scale, not because they were better for the places we live. What has changed recently is that engineered natural materials can now match conventional ones on performance, which makes the question worth asking properly.

The part that made me surprised

Then I hit the studies nobody quotes in marketing copy. One found cork insulation performing worse than polystyrene in certain environmental categories, such as acidification and resource depletion. The point is not that cork is bad. It is that a bio-based label, on its own, tells you very little. Whether a natural material is truly the better choice turns on questions that never fit on a tag.

What has been done to it? Many bio-based products rely on synthetic binders, coatings and fire retardants. Those treatments can release volatile organic compounds( VOCs – keep an eye on new articles coming about this) into the air of your home, and they can make a natural board just as hard to recycle as a synthetic one. A material’s afterlife is decided by its chemistry, not its origin story.

Where does it come from? Cork grows in the dry Mediterranean. Hemp needs a lot of land and faces legal restrictions in many countries. A natural material shipped across the world, or grown on land that could not be spared, loses much of its advantage. Local availability is not a nice extra. It often decides whether a material makes sense at all.

What happens at the end? This is the least researched stage of the lot. Real end of life data for bio-based materials barely exists yet, while steel and concrete recycling improves every year. The comparison is not standing still, and pretending otherwise would be dishonest.

How was it measured? Two studies of the same material can reach opposite conclusions depending on where they draw the line. Count only production and timber looks unbeatable. Count the full life, including maintenance and disposal, and the picture gets more nuanced. One study found hempcrete walls could carry a higher global warming potential than brick, while straw walls came out clearly ahead. Same family of materials, opposite results.

The health question, since we all live indoors

We spend roughly 90 per cent of our time indoors, so what our surfaces give off matters enormously. Synthetic chemicals in conventional materials have been linked to building related illness, the kind of thing people mean when they say sick building syndrome. There is also early evidence that natural materials do more than avoid harm: occupants of timber interiors report lower stress, which researchers connect to our built in response to natural textures.

But the same caution applies here. A natural material buried under synthetic coatings is not automatically the healthier one. It depends on the composition and the treatment, which is exactly why we publish both.

On cost, the pattern repeats. Natural materials can cost more upfront, mostly because supply chains are still small and fragmented. Over the full life of a home, though, several studies found bio-based construction works out cheaper than concrete, largely through lower energy use over time. Cheap at the till and cheap over thirty years are very different claims.

What this changes at Elken

Mostly, the reading confirmed why we built the Elken Standard the way we did. But it sharpened three convictions.

Composition and treatment matter more than the label. This is why we ask every maker what is in a product and what has been done to it, and why vague provenance claims never make it onto the site. Natural is the start of the conversation, not the end of it.

Known origin beats a good story. If a material’s sustainability depends on where and how it was grown, harvested or recovered, then you cannot judge it without knowing exactly that. It is the entire reason we work with a small number of makers we know by name.

Longevity beats everything. The most reliable finding across all those papers is that a material used for decades outperforms almost any clever alternative that gets replaced in ten years. The most sustainable product really is the one you never replace.

So the honest answer to whether natural materials are more sustainable turned out to be: usually, when they are chosen well, for the right use, from a known source, and made to last. That word, when, is the whole job. It is what we spend our days on.

If you would like the long version of the academic essay, I am happy to share it.