With all that's been written about being “green,” one would think there must be some definitive guideline out there. Isn't there some process, some simple list enlightened 21st-century contractors can follow to ensure they're making the greenest decisions?
Well, no. The sad fact is that while judging something to be green often is a true/false call, the supporting arguments aren't always that simple. And they can be downright misleading.
Take concrete, for example. We know now that, despite its signature grayness, this marvelous mixture of cement, sand, gravel, and water is a versatile, economical, and durable construction material. Yet many deny that concrete is green, pointing to its “carbon footprint.” Are the naysayers simply wrong? Or are owners, designers, and contractors doing something bad?
At least part of the answer lies in the complex nature of what it takes to be green. The materials of construction alone do not define a project as being green. It also requires a project design that optimizes the use of those materials and makes provisions for minimizing operation and maintenance requirements over the life of the structure. Additionally, how the contractors building a project conduct themselves on a day to day basis can affect how green the project is.
Defining green materials
It's good news for concrete contractors, and indeed all construction professionals, that concrete is an en vironmentally friendly construction material—it has all the potential to be green. A thorough life-cycle assessment, including environmental and cost factors, shows that it's economical, too. The fundamental considerations for such an assessment are simple.
Acquisition of the raw materials. This includes things such as mining and transportation.
The production or manufacture of the material. Cement production is admittedly energy-intensive and produces unwanted byproducts. But having identified those weak points, cement makers have committed to and already are making significant improvements in both areas.
Transportation of the material to the building site. Much of what goes into concrete is local material. Thus, compared to transporting materials over great distances, transportation is kept to a minimum.
Assembly and construction. Although some formwork can get complicated, it also can be designed and constructed very efficiently. For all but the most complex structures, good planning and design can maximize material reuse and minimize labor requirements.
Operation over time. This includes energy consumption, maintenance, repairs, and renovations, and is an area where concrete shines. Its long-term durability—which has comparatively low maintenance requirements—goes far in offsetting manufacturing negatives.
Decommissioning considerations. Again, this is an area where concrete does well. Like the material acquisition item, analysis of this part of the environmental and financial cost of concrete requires thorough treatment. However, considering the potential for recycling and reuse of the concrete materials resulting from the demolition of a concrete structure at the end of its useful life significantly lowers this as a cost item. Additionally, other residual effects of concrete rubble—toxicity, health effects, acidification, climate change—essentially are nonexistent.
Design considerations
Of course, the way a construction material is deployed can make a significant difference in the end result. The material can be all green, but its use has to be green as well. Beginning with a good design is critical, but defining what makes one better than another is not an easy task. Several rating systems have been developed to help designers in the decision-making process. One system that is gaining wide acceptance across the United States is the LEED Green Building certification developed by the U. S. Green Building Council (USGBC).
The LEED system, which is limited to buildings, considers strategies employed in five areas: sustainable site development, water savings, energy efficiency, materials and resources selection, and indoor environmental quality. First released in 2000, LEED now addresses various types of construction as diverse as new commercial projects, evaluation of existing buildings, and home construction and remodeling.
