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Brick builds a sustainable future

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As a traditional material that can be used in new and more effective ways, brick has good green credentials

Today's brick industry is modern and forward-thinking. Its investment of more than £400 million in the past 15 years alone has resulted in large-scale efficiencies. These include a reduction in energy use since the middle 1980s, and actively and measurably reducing emissions. These process changes have been employed by Hanson Brick, which led the way in the late '80s with the introduction of its popular Kempston stocks.

The brick industry is taking an active role in management of the environment. The development of the Kings Dyke Nature Reserve in Peterborough, home of the Fletton brick, is an example of the way in which Hanson Brick accepts the initial impact of its manufacturing processes. We have responded with a restoration programme in accordance with internationally accepted standards. The codes of environmental management for extraction and restoration are already in place and will be subject to continual appraisal and refinement.

Considering the whole building over its lifecycle, allowing brick to demonstrate its real attributes and remembering that the impact of material production is a very small element of the lifecycle impact is important to understanding brick's environmental impact. Some 90 per cent of the energy associated with a building is consumed in its use phase. It is also necessary in the lifecycle approach to ensure that every decision-maker is aware of the industry's aims and objectives. This places considerable responsibility on planners, builders, designers and their clients. As a materials producer, Hanson is both willing and keen to play its part in the process.

The introduction of cavity walls saw the demise of masonry as a structural material in favour of steel and concrete frames. This was not surprising, since the new frame methods allowed rapid construction of the superstructure followed by the infill of walls.

Additionally, the cavity wall, with its thermal insulation and rain resistance, provided a superior environmental barrier to the elements. And of course brickwork maintained its durability and aesthetic appeal.

During the 1970s, promotion of masonry exploited the potential of structural brickwork. Brick companies reminded people of the historical use of masonry, when buildings consisted of massive loadbearing walls which supported floors and the roof structure. This campaign was successful but it tended to steer designers to specific solutions for particular problems. For example, fin and diaphragm walls were incorporated in the designs of sports halls, swimming baths and any other large public buildings that required open space and no internal columns.

More recently, structural brickwork had a new lease of life thanks to a construction promotion of far greater importance - sustainable construction.

Environmental engineering and sustainable building are a vitally important aspect of design since we are not now simply selling materials and structures. We are concerned directly with the protection of the planet.

One area that is becoming increasingly important is life-cycle costing, which involves assessing the total value of a building element. It starts from the extraction of the raw material, and goes through the manufacture of the desired components from that raw material, to the building design and construction. Also included are the contribution made by the components to the overall efficiency of the building, waste, health and safety, cost and ease of construction, repair and maintenance and the end-of-life recyclable value.

We need to ensure that we do not just use brickwork for the sake of it. It is hard to imagine a built in situ wall that could make better use of components than the current system of clay facing brickwork for the outer leaf, insulation and a concrete blockwork inner leaf. This exploits the best qualities of all elements - aesthetics and durability for the outer leaf, cost, speed and thermal properties for the inner leaf.

However, with a little imaginative thought we may still exploit the best from all materials.

Off-the-frame cladding is a good example. The superstructure for a large building would still be erected in, say, structural steelwork. But instead of building the cavity wall within the structure (where it is necessary to support masonry off expensive shelf angles at every three metres height) we could design the external walls so that they are built for the full uninterrupted height of the building from ground to eaves level. Consider, instead of a traditional brick and block wall, the construction of a 215 mm outer leaf of clay brickwork.

This has a number of advantages:

cost savings by the elimination of stainless-steel shelf angles;

reduction in the number of wall ties;

elimination of lintels over doors and windows; and elimination of horizontal movement joints.

There are also significant savings to be made with the superstructure:

edge beams, which no longer need to support masonry, will be reduced in size;

smaller structural beams with a reduced load will allow smaller structural columns;

foundations for the external walls will invariably be simplified due to the uniform distribution of wall loading.

There is an obvious concern with this form of construction that a 215mm wall presents an increase in the bricklaying costs (as well as the use of more bricks). This must be weighed against the other savings mentioned previously. Furthermore, where the architect wants to achieve a traditional bond in English or Flemish brickwork, this is attainable without expensive or time-consuming site cutting.

Another factor with this design is the increased thermal mass. In other words, the thicker the wall, the slower the heat flow will be. Off-the-frame cladding solutions are increasing in popularity, particularly on large commercial projects.

As an alternative, consider the steady increase in popularity of both timberframed and lightweight steel-framed structures. In either case it is not unusual to provide a single-skin brickwork outer leaf, with insulation and plasterboard dry lining.

Again concern arises when constructing in heights greater than four storeys, when it has commonly been assumed that the differential movement between the brickwork and its frame would lead to problems at both eaves level and around window frames. Single-skin brickwork and frame structures have also brought about other design and detailing problems for the outer leaf.

The structural design of these types of frames has never taken into account the contribution by the masonry towards the overall stability of the structure. This problem was addressed recently in the TF2000 project at the BRE's large-scale structures testing facility at Cardington.

A six-storey timber-framed building was erected and a single-skin brickwork 'cladding' was provided. Research by BRE, TRADA, Ceram Research and the Brick Development Association evaluated many aspects of the building's performance, including such work as fire tests and robustness tests.

Two projects that were of particular interest to the brick industry were:

1. the assessment of differential movement between brickwork and timber;

2. the shielding effect of single skin masonry to a timber frame structure.

The results were most encouraging and were documented comprehensively. To summarise, the differential expansion testing programme has shown that the amount of in-situ measured movement for brickwork was within the allowable design constraints. It is notable that no shelf angles were used and that, as with off-the-frame cladding methods, the brickwork goes up the full height of the building.

The brick industry realises the need for good, standardized data to provide recognised and internationally accepted manufacturing to the building codes.

Collectively, brick manufacturers are members of a consortium of UK materials producers who work with the BRE to produce recognised methods for the production of environmental profiles of materials and buildings. This has resulted in a UK National Database of Environmental Information for Construction Materials and Components.

Hanson Brick's plans for the future are in line with the rest of the brick industry but its innovative approaches and investment strategies provide the tools to implement action. Continual communication with design-industry liaison groups through the CPD training programmes will remain a priority.

The further development of BRE Environmental Profiles Data provides an opportunity to work even closer with the heart of materials manufacturing processes and is likely to continue while the need to reduce waste and energy remains an issue.

Energy efficiency is improving steadily, and there are many examples of good environmental management for the Best Practice Programme in which the aim is to work to international ISO 14001 standards as well as to European Environmental Management and Audit Schemes. This compliance is essential if brickmakers are to avoid losing out to competitor materials.

The sustainability credentials of brick contribute in many ways to the lifecycle issue. As a material, brick scores highly for its durability and low maintenance, and its aesthetic attraction contributes to the length of time the building is allowed to stand.

Brick is a flexible material, allowing ease of remodelling, extension and addition.

Its suitability as a material for recladding can also avoid the cost of demolition and rebuilding. Bricks can be reused and recycled, or even crushed and used as raw material for new bricks. They provide structural qualities as well as acting as an insulator and sound barrier. The attributes of brick clearly contribute to the essential aspects of sustainable development.

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