Concrete: Can it be Green?
"Embodied energy is the energy consumed by all of the processes associated with the production of a building, from the acquisition of natural resources to product delivery." and as you can see from the graph, Concrete has far and away the highest of any material. It also has far and away the lowest value when it comes to recycling at the end of its life. Thus we were surprised to find that a major sponsor of the Green Building Festival in Toronto today was - the Cement Association of Canada. This is like a cigarette company sponsoring a medical convention. Like cigarettes, you can get concrete in lite versions with recyclables in it that even can get you LEED points, so some concretes are greener than others, but still it is a stretch. the Portland Cement Association lists five ways that concrete helps build Green, all of them questionable, and each giving LEED points.
Five Ways Concrete Helps Builds Green
1. Concrete creates sustainable sites. They may get LEED points but it is a misuse of the system. If you build an underground garage you reduce a building footprint and get a point. underground garages are built of concrete. Pouring concrete to store cars gets points?
2. Concrete enhances energy performance. Yes, it has great thermal mass, but no insulation value
3. Concrete contains recycled materials. Like fly ash and slag from other green industries
4. Concrete is manufactured locally. And destroys local environments through gravel excavation and transport, mixing plants and delivery in big heavy vehicles.
5. Concrete builds durable structures. Unfortunately, we would like to be rid of some of them.
The ::concrete network makes even more specious arguments.
The Cement Association of Canada has pages on the sustainable benefits of concrete, complete with obligatory pictures of smiling children.
Read "What Makes a Product Green from the ::BuildingGreen.com and it is hard to imagine concrete.
Read the wonderful "::Design for Lifestyle and the future" , Australia's guide to environmentally sustainable homes, and learn about embodied energy.
Conclusion: There is a place for concrete, but it ain't at the Green Building Festival.