Last week I wrote about one of the common myths of green building: that it has to cost more to build green. This week, I'll tackle another myth: that green building is mostly about materials.

This isn't quite as significant a misconception as it was a few years ago, but there are still a lot of people who think green building is largely about using products that are made from recycled waste materials, or agricultural products, or rapidly renewable products like bamboo. It is still common to hear about how "green" a building is because of the recycled-glass tiles in the entrance foyer or the carpet that's made from recycled soda bottles.

Using recycled-content and bio-based materials is a great idea, but materials are only one--relatively small--aspect of green design. Usually more important are the following:

• Where we build. The location of a home or commercial building has a huge impact on how much energy is used (and pollution generated) in getting to and from it. In fact, it's not unusual for the "transportation energy intensity" of a building to be greater than the direct energy intensity of that building. In other words, for many structures, especially office buildings and retail stores, more energy is spent getting workers and customers to and from those buildings than the buildings themselves use. As energy codes are strengthened, this becomes a more and more significant issue.
• Energy performance. To be considered green, a building has to be energy efficient. This is usually the number-one priority in green design, and it's the reason that energy-saving features typically earn the most points in green building rating systems like LEED (though I often argue that location is even more important). With existing buildings--where we can't change the location--reducing energy consumption is almost always the number-one greening priority.
• Indoor air quality. A building that makes people sick can't be green. As we focus on other measures, it is vitally important that we pay attention to indoor air quality. This involves addressing moisture sources (that can cause mold); seepage of radon into the building from surrounding soil or rock; formaldehyde offgassing from cabinets and wood panel products; and VOC offgassing from sealants, adhesives, and coatings.
• Water efficiency. In some parts of the country, conserving water is a top priority. Even in areas that aren't particularly arid, water can be a significant issue during times of drought, or if sewage treatment capacity is limited. As we saw in the Southeast in late 2007, drought can be a huge issue even in areas where water has long been plentiful. In the eastern U.S. our reservoirs are generally a lot shallower than in the West, so the impacts of drought are felt more quickly, and we're not conditioned to think about water conservation. Some experts suggest that, in the coming decades, water may be an even bigger concern than energy.

Green building is about the integration of a lot of issues, including all of those listed above. Material selection is certainly something we should pay attention to, but it's rarely the top priority. Don't ignore the materials being used in a new building or renovation project, but pay more attention to these other considerations.

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