In honor of the HBA Green Building Week here is a green building story for your enjoyment. Don’t miss the Eco-Vative Green Building Products Expo tomorrow and Green Building classes this week.
Concrete is one of the single most environmentally friendly construction products available. It offers stability, durability and design flexibility for the residential marketplace and environmental advantages through every stage of manufacturing and use. And it offers sustainability. Because old concrete can be recycled it can be reused almost indefinitely. The following are concrete’s primary environmental benefits:
Created From an Abundance of Raw Materials
Concrete draws upon some of the earth’s most common and abundant minerals for its raw materials. Portland cement, which makes up about 12% of concrete, is manufactured from limestone, clay and sand. Sources of aggregates used to make concrete — sand gravel and crushed stone — are plentiful. In addition, aggregate can contain recycled materials such as slag, a by-product of steel manufacturing. Also, when using Portland cement, a portion of it can be replaced with fly ash, a by-product of coal-burning power plants, and similar materials.
Fuel to Produce Concrete Can Come From the Waste Stream
The process of making cement also can use recycled materials. High-energy wastes such as old tires can be used as fuel in the cement-making process. One million old tires can fuel a single cement kiln for a year — conserving fossil fuels and keeping old tires out of landfills. Other recycled waste used in the production of cement can include used motor oil, disposable diapers, industrial solvents and sludge.
Local Production Reduces Transportation Costs and Fuel
Cement and concrete supplies are highly local or regional. At least 60% of all concrete is produced within 100 miles of the construction site where it is used. Wood and steel products, on the other hand, typically have to be transported hundreds or, sometimes, a thousand miles or more to the job site.
Concrete’s Thermal Mass Yields Energy Savings
The thermal mass of concrete buildings and homes reduces temperature swings — and can save owners energy year-round. During the air-conditioning season, for instance, a concrete building generally only will require the cooling system to be in operation at night — during off-peak hours when electric companies can produce power more efficiently. Also, many of today’s concrete wall systems, such as insulating concrete forms (ICFs), combine the mass of concrete with foam insulation — creating an exterior wall envelope that through thermal mass, reduced air infiltration and increased R-value can reduce heating and cooling costs by as much as 40%.
Concrete Reduces Construction Waste Because Fewer Components Are Needed
Concrete construction requires fewer kinds of building products — such as sheathing and insulation —than wood-frame construction. Plus, concrete is created on an “as needed” basis, eliminating the waste inherent in sheet goods and dimensional products for framing. Because fewer materials are needed, building with concrete puts less waste in landfills. And if replacement or demolition is required, old concrete can be ground up and reused as coarse aggregate or pavement sub-base material.
Concrete’s Durability Can Weather Time and the Weather
Concrete does not rust, rot or burn, so housing stock built with concrete components such as wall systems can stand for generations. Concrete is less susceptible to moisture damage and can generally “breathe” and dry — if the concrete structure is not too close to adjacent structures. Concrete driveways will far outlast their asphalt competitors, while items such as fiber-cement siding are much more durable than competing cladding materials. By simply outlasting other materials, concrete conserves energy and resources. In addition, homes built with concrete also are more likely to withstand natural disasters such as hurricanes, tornados and fires than traditional wood-frame housing stock.
Concrete Homes Can Create a Healthier Indoor Environment
Concrete can promote a healthier indoor atmosphere because it is practically inert and requires no volatile organic-based preservatives. The solid concrete walls in homes built with exterior concrete framing systems serve as a continuous barrier against air infiltration, which can greatly reduce the level of airborne dust and allergens when a fresh air exchanger and humidifier are used.
Concrete Homes Are Increasing in Popularity
From 1999 through 2005, the share of homes built with concrete walls increased from 5.9% to 17.9%. This increase not only measures a growing popularity in concrete homes, but a change in attitudes as well. Not many years ago, the idea of building a concrete home generated blank stares among potential home owners or prompted questions about why anyone would want to do such a thing. Now, however, many consumers are aware of this type of construction, understand its benefits and want to know how much it will cost and where to find the nearest supplier or builder. A combination of factors is driving these changes in perception and attitude — a rise in energy prices, an increase in the amount and destructiveness of natural disasters and the rise of the green building movement.
Aesthetically, the Depth of the Windowsill Tells the Tale
While growing in popularity, many people still have the mistaken perception that a concrete home looks more like a bunker or fallout shelter than a home. Aesthetically, however, with most concrete wall systems in use today, it’s difficult to drive down a street and pick out which home is concrete. Concrete home exteriors are finished with siding, stucco, brick and stone, just like wood-frame construction. Also, like with wood-frame construction, the interior of a concrete home is finished with drywall, though with some systems such as precast concrete, interior walls are simply painted. For both outdoor and indoor areas, decorative concrete is rapidly growing in popularity for all types of home construction. Traditional concrete flatwork can be stained, stamped, stenciled or polished to achieve a wide variety of patterns, colors and textures. Beautiful custom concrete countertops can achieve a similar range of styles.
So what’s the primary aesthetic difference between concrete homes and wood-frame construction? Simply put, the walls of a concrete home are thicker. But the only way to tell the difference on a finished home is by the greater depth of the windowsill of a concrete home — which is a definite bonus in the eyes of many home owners.