The Spring Hill "Enviro-Cottage" design called for new flooring to support the passive solar design. But what should you use if you want your flooring to be sustainable, durable, energy efficient, recyclable and affordable?
When selecting an enviro-positive or, at least, enviro-neutral flooring material, it's hard to go past concrete - one of the oldest and most versatile building materials on the planet. Concrete is the second most widely used substance around the world (in fact, the only substance that beats it is water!). But, as with every building material you choose, there are positives and negatives associated with concrete.
Concrete negatives:
- Quarrying billions of tons of limestone degrades the landscape
- Transporting heavy materials pollutes the air
- The production process uses large amounts of electricity (consuming up to 2% of electricity in the world)
- Water is used, and often wasted, during manufacture and, unless managed well, ground water and river systems can be polluted
- Creating active lime, the main part of cement, results in CO2 emissions (about 1 ton per 1 ton of cement produced, resulting in about 8% of the CO2 produced worldwide)
If we want to select materials that are considerate to the environment and we intend to conserve energy, reduce air pollution, recycle and conserve natural resources then how does concrete stack up, given those considerable negatives?
Concrete positives:
Minimal Waste
Compared to other building materials, concrete presents very little construction waste. Only what is required is delivered to site, any leftover is returned to the plant to be reclaimed or reused as fill material. It doesn't need to be trimmed or cut after installation. Increasingly water recycling systems are being used to conserve and re-use water resources.
Recycled Content
Increasingly fly ash, slag cement, and silica fume (all industrial by-products which might otherwise end up as landfill) are being substituted partially for cement. Recycled aggregates are replacing newly mined gravel.
Energy Performance and Thermal Mass
Using thermal-mass (and good insulation practices, window placement, and generous eave overhangs), internal house temperatures are "naturally" moderated by storing and releasing energy when needed, keeping you warmer in winter and cooler in summer. Mechanical heating and cooling requirements are therefore lowered, and in the case of the "Enviro-Cottage" completely eliminated. Less energy is needed to heat and cool the home, lessening the long-term environmental impact of the building.
Local, Natural Products
Concrete is made from readily available and mostly local natural resources: water, sand, stone and cement, minimising environmental impact due to transportation.
Durability
Concrete will not rust, rot or burn, and is resistant to termites and vermin. Meaning less energy and resources needed over time to repair and replace it. It can withstand most natural disasters like fires, cyclones and floods resulting in less destruction and property loss and less human displacement when disaster strikes.
Low Emissions
Concrete is a natural, inert material. It has low VOC emissions and so does not degrade indoor air quality. Concrete floors can help reduce allergies.
Flexibility and Finish
Concrete can be moulded to any shape or size and be coloured, stamped or stencilled. The "Enviro-Cottage" will use a burnished concrete finish for its main floors.
Reusable and Recyclable
Concrete is 100% recyclable and is being increasingly produced from recycled materials. Given its strength, reusing an existing structure rather than knocking it down and starting again makes better environmental sense. This also reduces the amount of demolition landfill. Old concrete that has served its useful life can be crushed and reused as aggregate base.
Cost
Concrete is one of the cheapest building materials available for home construction. This leaves budget available for other enviro-friendly products such as PVCs or water tanks.
Concrete for the Spring Hill "Enviro-Cottage"
Project's thermal mass floors, walls, footings, retaining walls and pool have been provided through a generous partnership with Wagners, which has a number of plants across Queensland including Brisbane, Toowoomba and Townsville. Wagners was viewed favourably given a number of environmental initiatives it has taken including:
- Being the first concrete company in Australia to introduce the Wastesaver unit, a revolutionary system that enables the recycling of water, reduces the cement used, and allows solid waste to be remixed back into the production line. Results at a single plant include reducing greenhouse emissions by more than 45 tons, saving 2.4 million litres of potable water, reducing diesel use by over 33,000 litres, and reducing landfill waste by 9,000 tons.
- Wagners is part of Independent Fly Ash Brokers, which distributes fly ash from the Millmerran Power Station, previously dumped as land fill. Wagners utilises the fly ash in its concrete production processes.
- In 2009 Wagners will open a new cement plant, specialising in blends utilising fly ash and blast furnace slag, a waste product from the steel production process. These technologies will help reduce greenhouse gas production at the new plant by up to 20%.
Concrete isn't the perfect building material, but then, at this stage, there's probably no such thing. What's worth remembering is that concrete has its advantages and is, in some respects, more environmentally friendly than often thought. Hopefully the concrete industry will continue to innovate and find new ways to lessen its environmental footprint, so we can all take advantage of the many benefits of concrete.
