Denise Bester: Rubbish good for building your house

Wasted Resource?

People have been building dwellings for over 14,000 years, largely using materials accessible in their immediate environments. Whether that be wood, stone, clay, reeds, or ice, the practice has always been to use what's available and abundant.

It's only since the advent of modern industry and mass production that we have been using products that are mass produced, and then transported over often vast distances to reach our doorsteps.

Cement, the key ingredient in concrete, is highly energy intensive. According to the international Cement Sustainability Institute, it accounts for around 5 per cent of global human-induced emissions of carbon dioxide, as well as affecting a wide range of sustainability issues, including emissions to air and water, natural resource depletion and worker health and safety.

Well, what choice do we have these days? At least in our urban environments, there aren't really any abundantly occurring building products available. Or are there?

We do have one thing in excess. Every week our wheelie bins hit the kerbside overflowing with rubbish and recycling. Tonnes and tonnes of domestic and industrial waste heads to our landfill and recycling dump sites. And with the downturn in the global economy, the usual buyers of significant portions of our recycling in Southeast Asia are demanding less.

So, we have found our abundantly occurring product, but can we use it for building? Well, there are some people out there who think we can.

At the University of Nottingham in Britain, Dr John Forth and Dr Salah Zoorob have invented a building block made almost entirely of recycled glass, metal slag, sewage sludge, incinerator ash, and pulverised fuel ash from power stations. According to Dr Forth, this eco-friendly 'Bitublock' consists of up to 100 per cent recycled materials, and uses less energy to manufacture than a concrete block. It's about six times as strong, which makes it a high-performance product. Dr Forth hopes the Bitublock will completely replace energy-intensive concrete as a structural material.

Then there's the sustainable architecture maverick, Michael Reynolds, otherwise known as the "Garbage Warrior". He has been experimenting with waste-building for over 30 years in the US. His "earthship" prototype building uses recycled automobile tyres filled with compacted earth as the major structural component. It also uses glass or plastic bottles, and aluminium cans as bricks, making for strong and easily constructed walls. One of the earthship principles is that truly sustainable homes should have low technology and skill requirements to construct, meaning the layperson can assemble their own home with minimal training. The result is houses that are very energy efficient, durable, and easy to build.

It makes sense to turn our waste products into valuable resources, and change something that we don't want - trash - into something that we do want - beautiful and sustainable homes. The ideas are out there, and they're certainly food for thought.