Concrete in a Sustainable World
Tarmac - one of the UK’s largest suppliers of concrete building materials - has harnessed the integral properties of concrete, such as high thermal mass, strength, recyclability and durability, to create building products that play a key role in delivering a more sustainable future for communities and the environment.
By Jim Troy, director of concrete and mortar technologies at Tarmac.
Positive impact
“As a building material in the broadest sense, concrete has a wide variety of applications, therefore its sustainability must extend beyond the physical properties of the product itself to the impact it has on the world around us. By devising imaginative building solutions that use this established product, we can reduce the impact we, as a collective community, have on the environment.
Take just one example, such as the need for more housing. Over the next decade, the Government estimates that we will need to build around 200,000 new residential properties every year. To meet this target, we will have to use land more efficiently and build high quality, thermally efficient, homes. This is where products such as our blocks range have a big role to play.
People may think of concrete blocks as old fashioned, but the fact is that they are one of the ultimate sustainable building materials. They are durable – capable of lasting hundreds of years – and have high thermal mass properties, which means that block-built houses retain heat (and cool) much better than timber and steel frame alternatives. In fact, using concrete as a building material can reduce energy consumption in commercial and residential properties by as much as 50 per cent.
Concrete also has great soundproofing qualities - a big plus when we’re likely to be living in much closer proximity to our neighbours in years to come. It’s also very safe. Concrete is non-combustible, and its thermal mass means that in the event of a fire it can absorb heat, thus acting as a fire barrier and giving people vital extra minutes to evacuate.
Projects like the Olympics, as well as ongoing investment in transport networks, leisure, school and health amenities, means that demand for concrete-based products will continue to grow – so you can see why we place an emphasis on developing products with strong sustainable credentials.
Concrete in action
Where concrete really proves itself is in the benefits it brings to structural applications. The fact is that 44 per cent of carbon emissions in the UK come from buildings, so we’re helping to reduce this statistic by designing sustainable concrete products that can be incorporated into all kinds of construction projects.
A good example of this is our new thermally efficient flooring solution called Heatsave Plus. Dense expanded polystyrene panels (EPS) are fitted between concrete beams to offer outstanding insulation properties. Heatsave Plus removes the need for additional insulation between floors, so heating systems can be turned down, saving on fuel costs and reducing carbon emissions.
As a nation, we can’t ignore the fact that our climate is changing. Average temperatures are increasing, and there will be a growing need to control internal building temperatures. Which is where concrete and its high thermal mass come into play.
Traditionally, energy-intensive systems like air conditioning have been used to control ambient temperatures, but changes to Building Regulations, increasing energy prices and climate change are making architects, developers and building occupiers reconsider their options.
We have pioneered a heating, cooling and fresh air ventilation system called TermoDeck as a sustainable and cost-effective alternative. It’s a high tech solution that uses a simple principle.
TermoDeck harnesses concrete’s naturally high thermal mass properties (also known as Fabric Energy Storage, or FES) and combines it with the principal of ‘night cooling’ to maintain stable, comfortable building temperatures. TermoDeck uses concrete hollowcore flooring panels to absorb and store heat generated during the day. Fresh air is passed through these hollowcore units at low velocities, allowing heat transfer between the concrete and air. Essentially, the concrete acts as a passive heat exchange element that transfers heat to - or absorbs heat from - the air, depending on whether heating or cooling of a room is required. Night cooling purges the accumulated hot air and heat from the slabs, preparing them for the next day.
The TermoDeck system also circulates this fresh air into rooms through a network of vents, which is especially important for buildings like schools, universities and offices, where high levels of concentration are required.
Thermocast is another heating and cooling system we offer that uses the same principles as TermoDeck, but this time the hollowcore concrete panels are laced with an internal matrix of polybutylene pipes. Water is passed through these pipes to maximise the thermal mass performance.
Responsible recycling
A key part of reducing our impact on the environment involves increased use of recycled concrete in manufacture.
We always endeavour to consider the possibilities for recycling at every stage of manufacturing as well as post-use. Our aircrete blocks are 100% recyclable and can use up to 97% reclaimed material in their manufacture.
Tarmac Topblock is also trialling a new waste ‘take-back’ scheme for damaged or off-cut blocks, which are returned to us from building sites and recycled into new products, rather than being sent to landfill.
In addition, we have a unique recycling service within Tarmac, which enables us to re-use concrete material from demolition sites, buildings and roads, motorway bridges and airports, and recycle it as aggregate for other applications. In total, Tarmac recycles approximately 200,000 tonnes of concrete every year. We even recycle concrete railway sleepers – that’s around 5,000 tonnes every year.
We use this recycling expertise when working on projects for clients. For example, for BAA at Heathrow Airport, we resurfaced the runway around Terminal 5, and used about 150,000 tonnes of concrete from the old runway in the construction of the new airstrip – some went into creating a sub-base layer, and some into new concrete.
Sustainability in practice
As you can see, we are leading the way in proving that concrete is one of the most flexible and versatile construction products available, and can used for virtually any application. No other material has the same adaptability, durability and in-built safety.
Certainly at Tarmac, a division of the globally successful Anglo-American group, we think concrete is the ultimate sustainable material and will continue to take it in new directions.
This is paving the way for a new generation of construction products that make concrete sustainability a reality.”
20 November 2007
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