When we think of greenhouse gas emissions, most of us envision a tailpipe spewing exhaust out of the back of a car. But 40% of the carbon dioxide that contributes to our warming planet comes from buildings. While some of that is a secondary effect of operational needs such as electricity, A/C, and heating, many GHG’s arise from resource extraction, manufacturing and production of the building materials themselves.
Of all the criteria covered by LEED-H and our own GreenBuilding 101 series, MATERIALS and RESOURCES has perhaps the broadest application and relevance. They are the ingredients, and choosing them wisely makes all the difference in terms of the overall impact of the building throughout its life. This is where ‘environmental footprint’ or ‘life cycle assessment’ come into play; as we learn in Cradle to Cradle design basics, the materials are in the picture from the first round of planning to the final stages of demolition or renovation.
Today’s series walks you through choosing ingredients wisely, being sure that the materials you select, and the resources it took to produce them, are a part of the whole picture of a sustainable home.
(Edward Caldwell Photography for Arkin Tilt, Belmont, CA)
1) Sizing Up Your Home
One of Inhabitat’s recurring themes is the virtue of a compact space. On the spectrum of difficulty in shifting towards a more sustainable lifestyle, consolidating your space is a pretty easy way to live more efficiently. A smaller home takes less material to build, and requires fewer resources to maintain indoor comfort; and these days, some of the most elegant and innovative interiors emerge from a creative use of compact quarters.
Berkeley-based architecture firm Arkin Tilt has a knack for creating tight, light-filled, energy-efficient homes often show-casing multiple solar systems and reclaimed materials in one project. And of course, Michelle Kaufmann‘s variations on the theme have become synonymous with micro-modern chic.
2) Framing the Argument
There are lots of reasons to love prefab, and where material efficiency is concerned, it’s all about the frame (or lack thereof). Replacing stick framing with wall panels saves resources and diminishes waste. The NRDC has created a handbook for efficient wood use in residential framing. Basically, where wood framing is used, optimum value engineering (using fewer framing members within code compliance) can cut down on the use of wood by 11-19% and lower framing costs significantly. Or better yet, eliminate wood framing and use prefabricated building components (panels and trusses) that are more efficient, durable, flexible and generally make for a tighter building envelope. SIPS (structurally insulated panels) use oriented strand board, which is produced from smaller trees that can be sustainably harvested. They have EPS (expanded polystyrene) rigid foam insulation in their core, which means fewer drafts, less noise, lower energy bills, and a more comfortable indoor environment.
(Michelle Kaufmann‘s Glidehouse)
3) Looking Towards Local
How does one decide if one material is more environmentally preferred over another? At this point the best answer to the question is simply to ask a lot of questions. It also helps to compare apples to apples. For example, rapidly renewable bamboo or plyboo is a good alternative to traditional oak flooring. But if reclaimed oak is locally available, it may be wise to opt for the product that doesn’t come from China…unless you’re in China, of course.
A number of useful checklists can be found, such as LEED-H, Built it Green or Healthy Building Network’s long list of Key Questions for Environmentally Preferable Building Material Selection.
(Ipe Trees in the Pantanal, Brazil)
4) Durability is Desirable
This one relates back in large part to our discussion of sustainable sites. The conditions under and around your home determine the ability of the structure to withstand all sorts of potential challenges to its integrity, not least of those being moisture, wind and temperature fluctuations. This is also tied into considering the offerings of local resources, as the naturally-occuring materials in any given location are most likely to be durable within that region. A great article at GreenBiz covers durability in depth, addressing not only the weather-related issues, but also insects, function, and even style.
5) Environmentally Preferable Products
Because ‘sustainable’ is open to interpretation, any manufacturer and a good marketing team can call their product ‘green’. And there are plenty of buzz words out there. Several third-party certification organizations have cropped up in recent years, to help police those ever-clever marketing folks from twisting the truth about the endless products out there. A good rule of thumb is to stick with the consensus based certifiers like LEED, FSC, and EnergyStar, and be cautious of trade association ‘greenwash’ labels that may create certifications to aid their own sales. Healthy Building News has a great article called The Label Game that goes into depth on this topic.
Recently the Brazilian hardwood Ipe has become a popular choice for decking and exterior cladding applications, due to its strength, durability, and corrosion resistance. But few people know much about its native habitat, or that it is covered in several feet of water for much of the year (which is how it adapted to be so hard and resilient).
But just because a species of timber is long-lasting does not mean it’s a sustainable choice. If it’s not FSC certified, chances are the tree was logged by clear-cutting virgin forest, without plans for habitat restoration. Before specifying a hardwood, find out where it comes from, who’s supplying it, and if there are FSC certified woods available. EarthSource Forest Products works with designers and contractors to find cost competitive FSC certified woods, based on availability.
6) Waste Management
In Bill McDonough’s famous 3-line vision for the transformation of design, waste=food. With this in mind, it’s best to turn as much of the material you discard at home into potential nutrients for plants and products in the future. Start a compost bin, separate household waste into organic, recyclable, and trash – and then find ways to cut down on the size of that third pile. Outside, you have options, too. Where frequently we let rainwater get away, there are materials such as biopaver, which capture and use rain, reduce storm water run-off, and use less overall material than impermeable paving.
Most importantly, during construction, demolition or renovation, be conscious of the materials you’re tossing. You can contact The Re-Use People to help mitigate waste and debris from going to a landfill. If you are unsatisfied with your city’s recycling program, contact your local PUC (public utility commission) or better yet, call the Mayor!
In San Francisco, enough public interest was voiced about waste management and healthy building tactics that the SF Department for the Environment has created as a resource for the community. Now eco-friendly mayor, Gavin Newsom, is competing with other mayors to make his city more green, aiming to achieve 75% waste diversion from the landfill by 2010, and zero waste produced by 2020.
How’s that for an environmental footprint?
Stay tuned next week for Part II of MATERIALS and RESOURCES