March 14, 2008

WILLIAM CONWAY/PROGRESS PHOTOGRAPHY

Clay brick is one of the most durable building materials around. Although its greatest susceptibility is to freeze/thaw cycles, it can last hundreds of years.

Focus on Concrete/Masonry

In well-designed buildings, clay bricks earn LEED points

PETER KENTER

correspondent

In a world of super-plastics, space age metals and nanotechnology-enhanced building materials, brick is still considered a prime choice as an environmentally sustainable building material.

Though sustainability has a wide range of definitions, as it pertains to building materials, it generally involves minimizing the depletion of the Earth’s resources and remaining relatively benign to the the ecology while accommodating the needs of the end-user.

“Clay brick is one of the most durable building materials around,” says Patrick Kelly, Masonry Systems Manager, with Hanson Brick in Meadowvale, Ontario. “Although its greatest susceptibility is to freeze/thaw cycles, it can last hundreds of years.”

Ontario is well served by the Queenston Shale, a large clay deposit existing below the Niagara Escarpment. “At the current level of usage, studies show that we have enough shale resources to supply us for well over 1,000 years,” says Kelly.

A clay quarry is extensively mined for 40 to 50 years, usually by the brick manufacturing company that owns it, and is then rehabilitated using engineered fill to replace the volume of clay removed from the area. Because the clay is chemically inert, it can be safely reused and recycled after it reaches the end of its original service life.

Kelly notes that Leadership in Energy and Environmental Design (LEED) point systems vary between Canada and the U.S. In Canada, a project can earn points for using a building material—such as brick—that is durable according to CSA standard S478.

“LEED does not endorse any particular material or product, but rather recognizes the environmental, resource or health merits of building design, construction or operations,” says Ian Theaker, LEED program manager with the Canada Green Building Council.

Theaker says that, when brick is employed and maintained in a well-designed building, it has several benefits recognized by LEED Canada credits: it can provide a durable, low-maintenance exterior cladding for thermally-efficient walls; it is typically manufactured locally, using local resources, with clay, sand and cement as the primary ingredients; when used in interiors of passive solar designs, it can provide thermal mass, storing solar energy gathered in the day for release at night, when heating needs are greatest; it is a source of minimal emissions of indoor air pollutants and with effort, it can be cleaned and reused or crushed for recycling as aggregate, for walkways or other uses.

But Theaker notes brick does have potential environmental and resource impacts that should be considered in its use.

“Mining of sand and clay can have major impacts on habitat and watersheds if not conducted responsibly,” he says. “Brick is energy-intensive to manufacture, and, as a heavy material, shipping it long distances results in large fuel consumption and CO2 emissions.”

Kelly notes that firing the brick in the kiln represents the greatest use of fuel, but that the brick industry as a whole has been reducing fuel consumption, resulting in an estimated 50 per cent reduction in energy consumption over the past 25 years.

“The kilns are better insulated and we improve the efficiency of the operation, for example, by using the heat from the cooling zone of the fired brick to dry the bricks going into the kiln,” he says.

“Every time we build a new brick plant, it features more efficient firing.”

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