Practicing sustainability has so many aspects that it can be hard to decide what to focus on. As a natural builder I spend a lot of time thinking that I really should be growing food, which seems more urgent since we already have a lot of functional buildings. Or restoring watersheds, since our relationship to water in the landscape is unstable enough without the extra threat of drought as a part of climate change.

I am still building, however. Why? Some statistics: In 1997, according to the U.S commerce department, about 36% of total energy use in the US was consumed in the operation of commercial (16%) and residential (20%) buildings. This figure represents almost 9% of total worldwide energy use for that year. Current construction methods account for 40% of material goods entering the global market The preparation, transport, and handling of clay soil onsite requires about 1% of the energy required for the preparation, transport, and handling of baked brick or reinforced concrete.

Green building refers to all of the practices that try to remedy the problems that these statistics indicate. These practices reduce the impact of construction by using lower-impact materials for construction and by designing buildings to maintain a comfortable indoor climate without relying on constant energy inputs. Many aspects of green building integrate easily into the urban environment: materials and systems are often designed to be direct substitutes for conventional practices, so their implementation doesn't require huge changes in code or awareness.

However, I practice natural building, which could be considered an aspect of green building. The term "natural building" to a non-builder is probably very vague, since "natural" appears to have so many convenient meanings these days that it no longer means anything at all. But "natural building" actually has a fairly specific definition. Natural building refers to a set of techniques that use locally available, unrefined materials as much as possible. What this translates to in practice is the use of local clay soil, straw, sand and gravel, non-industrial wood, and various other biodegradeable and creatively recycled materials. These materials are combined to create wall systems like strawbale, cob, adobe, rammed earth, wattle, and slip straw. As the third statistic above suggests, these types of buildings have the potential to have very low environmental impact indeed: the energy required to move and refine them is much lower than that which is required for most conventional building.

Natural building has historically taken place at the ends of dirt roads in rural counties, and is often stigmatized as being irrelevant to cities (and sometimes as irrelevant in general). This is only to be expected: it's very difficult for a culture to learn a skill that is so foreign to its habits under the full view of prevailing regulations, expectation, and habits. So of course the pioneers went up into the hills or out into the desert, and began investigation on their own terms. This investigation has continued for nearly a couple of decades now, and as a result we now know enough to bring what we have learned into other contexts.

Natural building stands to be very important in urban areas, for both tangible and intangible reasons. We have a lot of existing buildings, but many of them need both maintenance and retrofitting. The simplest way to integrate natural building with existing structures is to apply earth or adobe plasters over existing walls. Having clay-based finishes in the interior of a house has various benefits. Clay has the capacity to balance out interior humidity, as well as softening sound and adding thermal mass to stabilize interior temperature. Clay finishes on all kinds of walls are becoming increasingly common.

More ambitious retrofits include adding whole new rooms using natural materials, or using natural materials to increase the insulation or thermal mass of a building. Judy Knox and Matts Myhrman retrofitted their concrete block house in Tucson by wrapping strawbales around the entire exterior of the building.

But perhaps the greater relevance of natural building to cities is intangible. One of the greatest ecological dangers of cities is that they separate the people who live in them from the direct impact of their actions. This is true of most things that we do in this culture, but the effect is magnified in urban areas. Everything that we use in cities is brought in from elsewhere, and the cost of materials or services usually doesn't reflect the full ecological cost. The result is that there is no good context for evaluating the impacts of your actions. In the absence of a context it is very difficult to make choices to minimize the environmental cost of your life.

Natural building is one of the practices that can restore that context. Because the materials are mostly local, you can see what happens to land when you dig clay out of it or grow straw-producing plants on it, and what happens to a river when you take its sand or gravel. If you live in a city you probably aren't digging your clay out of your backyard, but it doesn't have to come from so far away that you can't observe what happens when it gets dug up.

With natural building you can also directly experience the true energy cost of construction, something that is very difficult to see in a conventional building. In other words, you are taking the raw materials yourself and refining them into a form that is good for building, and you are doing this with whomever you can talk into doing it with you. You therefore experience the effort that it takes not only to screen and mix the clay for cob or adobe or plaster, but also to convince everyone you know to come do the same things, and to feed them, and entertain them so much that they want to come back and do it some more (and more, and more...).

As a general rule, human energy plays the role in natural building that petroleum energy plays in conventional building. Thus natural building is often criticized as being too labor intensive to be practical; but in reality we are just being asked to face the impact that we unknowingly displace onto other people and living things. And if we can find a way to reverse that impact in the urban context, we can do it anywhere.