With support from government, off-site manufacture using timber frame systems is seen as the sustainable construction system but brick is still the most favoured building material with more than 80% of new homes using it structurally or as cladding. There is a general preference among the public and planning authorities for brick finishes on buildings. The vast majority of homes with a timber frame, will use brick for cladding. But the use of bricks has not grown in the last few years. The brick industry is now fighting back by improving the product’s sustainability performance by reducing the energy used in its manufacture.

Michael Driver, director of the Brick  Development Association, argues that taking into account the durability and longevity of bricks, the lifetime environmental costs of a brick built structure are less than other products – and the environmental performance exceeds them – particularly in terms of thermal mass. As evidence Driver points to the BRE’s latest Green Guide which gives bricks an ‘A+’ rating.

In the last five years the major issue of energy consumed in firing the bricks has been reduced to some extent. The basic manufacturing process has not changed, but renewable energy sources are being used.  Some factories use methane from landfill sites to generate energy for the kilns. The proportion of recycled materials in bricks is increasing. Alternative recycled and secondary sources such as ash, hydrocarbons and organics now make up on average about 12% of a new brick.  The water used in the production process is also reused.

Many timber frame systems use materials, which have to be imported long distances from other parts of Europe and the north America. The brick lobby  points out that the extensive range of factories across the UK and the availability of the raw materials, means that on average each brick needs to travel about 80 miles from a factory to the construction site.

New brick products are seeking to reduce their carbon footprint and increase their environmental performance. Brick is generally used alongside concrete breeze blocks in heavyweight construction but this is now changing. Manufacturers, such as Hanson are producing natural clay bricks which are not fired in a kiln. These blocks, which are designed for internal use, are made up of compressed clay allowed to dry naturally. An additive makes them water resistant. Paul Lacey from Hanson points out the low level of embodied energy in these new products.

Timber frame has led the way in off-site manufacturing, but the brick industry is seeking to catch up rapidly by developing both custom designed and standard components which can be delivered and assembled on site. Rather than using traditional mortar the preassembled walls use a resin based mortar to create panels which are then delivered to the site.

Companies such as Ibstock, will construct bays to order. Driver sees the days when brick built bathroom or kitchen pods will be constructed in the factory. One key requirement is the availability of a crane on site to lift the panels into place. The benefits of off-site manufacture are similar to other construction systems in terms of reducing waste on site, a more consistent build quality and health and safety. “There is a reduced need for scaffolding,” Driver points out.

Whilst timber frame manufacturers face skills shortage, Driver maintains that traditional brick laying skills are readily available. “The colleges have few problems filling their places – to ensure the ready availability of bricklayers, the contractors and subcontractors need to plan ahead,” he points out.

The longevity of brick as a material and the low maintenance requirements are claimed as a clear advantage over alternative materials. Many of the manufacturers give 60 year warranties on the materials but the BDA suggests that brick built structures can last a lot longer. In addition, it is easier to adapt a building with a heavyweight structure, than a lightweight frame. Driver points to the ability to knock down walls – or to add on sections. “If the building has been demolished the bricks can be reused, particularly if lime mortar has been used,” he said. “Or it is quite common for the bricks to be ground up and used for aggregate,” he added.

One of brick’s advantages is that it gives buildings thermal mass, so avoiding overheating during the summer. Some have argued that in fact, buildings can have too much thermal mass absorbing heat, which was intended for the room. Driver suggests that this problem can be avoided if a low level heating is used over a longer period. “Lightweight buildings work in schools which are used intermittently and so blasts of heat are useful but brick buildings are good where continuous heat is required.” He also pointed to the ventilation advantages of bricks, which allow a building to breathe.