The materials used in the construction industry and the processes involved in making them are a major contributor to CO2 in the atmosphere. Certain materials such as concrete and steel intensify the effect, as they use huge amounts of energy in their production, and require major transportation to get them to site. These costs are off the energy budget sheet in normal builds.
The use of alternative materials such as sustainable timber, recycled materials, materials from renewable sources and new application of materials (composites) can reduce the amount of CO2 and energy expended during a construction project, with some producing further savings during the life span of the building due to greater efficiency.
Materials production requires around 75% of the energy used in construction. In a developing country such as India, it is estimated that the brick industry produces 22% of the CO2 emissions by the construction sector and requires around 27% of the energy used in building materials production.
There are many materials used in building and DIY so we have split this large section into many smaller pages.
The UK brick industry manufactures about 2.7 billion bricks per annum (2003), consuming approximately 8 million tonnes of raw materials, primarily clays, marls, silt- and mud-stones from across the UK. The raw materials are variable in characteristics and produce bricks and paving slabs of wide-ranging performance.
The UK brick industry is a major national energy user with a yearly consumption of approximately 4.06 billion kWh equivalents of natural gas, (= c. 138.7 million therms, = c. £ 37.5 million) based on 2003 energy data from CERAM (materials and ceramics research body). Any potential savings on the volume of the energy used to manufacture the bricks would offer significant financial savings as well as reduce CO2 emissions.
Brick has been around for at least 7500 years, the first use is in upper Tigris, and in 2007 a new type of brick was invented based on fly ash, a by-product of coal power plants. Bricks are small ceramic blocks that are placed by hand - and it is this ease of use and long history that makes them so versatile and popular.
Bricks have a variable cost. Used bricks, which are esteemed for their rich colour and interesting visual effect, can be around 1 UK pound each, whereas standard mass produced bricks are around 25 UK pence. Handmade bricks are around 60 pence. Handmade bricks can add 2% to the price of a house, according to the companies that make them. A brick finish is very popular as it has a solid traditional appearance in the UK. The bricks age well, unlike concrete or most types of cladding.
Bricks reflect local variation as they use local clays, and have a high thermal mass. The handmade bricks are made from clay thrown (literally) into a mould, then dried for 48 hours before being fired in a kiln for 3 and a half days.
Adobe or mud bricks are green (sustainable) but are not suitable for all buildings. They have great green credentials though, as the main effort in their production is human labour and ambient warmth to dry - not even direct sunlight is required. Adobe bricks are made from clays and should not contain organic materials (unless a fibrous element like straw is introduced for strength and resilience). They last many years and just need some moisture protection such as wide eaves. Mud is the world's most used building material since most people in the world are still peasants.
The process of brick making has not changed much since the first fired bricks were produced 7500 years ago. The same steps used then are used today, but with refinements.
The phases of manufacture are: securing the clay, beneficiation (treatment of raw material), mixing and forming, drying, firing, and cooling.
Modern fired bricks are an excellent but limited and energy-expensive building material. They have been supplanted since the early 20th century for tall buildings by steel and concrete, as high structures are difficult to obtain. For instance, the Monadnock Building in Chicago (1896) is brick masonry and is only sixteen stories high, and the ground walls are almost 1.8 meters thick.
New types of building methods have improved this but it is still a problem. Brick is now used for low-rise buildings, or often in the UK, as a decorative cladding. This is very bad as bricks are very energy intensive in production, and need to be transported large distances to site. In the UK red brick is very common in older buildings, particularly in the North and around London (London red is a type of brick). Now bricks are used as cladding; often construction is by timber frame, concrete brick or block.
We recently built some eco houses in London using FSC timber, and were made by Council planning to clad three sides of the structure in red London brick in order to match the surrounding 100-year-old houses. We also had to put a grey slate gabled roof and bays etc. on the structure.
This is entirely bad, from a design and eco perspective. If people in year 1900 had to mimic year 1800 buildings, the current 'traditional' landscape would not exist. If this had always been done, we would now be living in modern houses, made to look like caves!
Wood can be used throughout construction projects and as well as being functional it is also pleasing to the eye with many people preferring its look and feel over metal or concrete. It is important to know where the wood has come from when green building to decide if it is a viable alternative to other materials.
See the Woods and Timber Building section for more details.
The Forest Stewardship Council (FSC) is an international non-profit organisation whose mission is 'to promote environmentally appropriate, socially beneficial and economically viable management of the world's forests'. This means that timber which is supplied as certified by the FSC has come from a sustainable source and is environmentally friendly.
A rival certification organisation has been set up, the Programme for the Endorsement of Forest Certification (PEFC) by the forest industry. However it is important to note that whilst the FSC enjoys endorsements from Greenpeace and the WWF the PEFC has not been endorsed by any environmental group. Their green credentials are not as clear.
In fact it is much derided as 'greenwash' as the minimum standard required to receive PEFC certification is low and varies considerably from country to country.
There is also no monitoring of habitat, and old forest can be felled.
So try and use proper FSC timber, or at least European softwoods rather than any hardwood.
If you want to use hardwood for doors make sure it is FSC.
Concrete poses a problem when it comes to green building. Whilst in comparison to other building materials concrete is environmentally friendly, the large scale of its use and its production requires a lot of energy. Green concrete is currently in its infancy and companies are experimenting with different forms of concrete, however these are still to meet current building standards.
Concrete also relies on by-products of other industries such as fly-ash (which is produced in environmentally unfriendly coal-fired power stations) and as such in its current form can not be deemed sustainable. Concrete is good for thermal mass as it stores heat, which makes it good where passive solar heating is a factor.
Glass used in construction will often need to be from fresh sources with many different types of glass available for use. Standard glazing can be made to be more energy efficient with the use of thermal barriers of neutral gasses such as argon between panes (this is common in double glazing installations).
Structural glass can be used on the south facing walls of a building to allow as much light and therefore heat as possible into a building. Recycled glass can be used throughout a building for example glass blocks as a privacy screen or in internal windowpanes. Every tonne of recycled glass used saves around 315kg of carbon dioxide emissions.
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