There are a number of ways of building that are becoming popular among environmentally conscious individuals. These green technologies are said to be “good for the planet” because they utilize indigenous or recycled materials.
A green building should address several issues: occupant health (this should always be the first priority), energy efficiency (conserving energy saves resources and minimizes outdoor pollution; renewable energy sources are best), resource efficiency (building with fewer materials, using materials more wisely, using renewable materials), environmental responsibility (using pollution-free heating methods, recycling scrap materials, using land wisely, disposing of hazardous materials properly), and economic viability (houses must be affordable, buildable, adaptable, and marketable). Popular examples of green building technology include rammed earth, adobe, and straw bale, but there are others.
Rammed-earth walls usually consist of a sand/soil mixture that has been packed into temporary forms until it is very dense. Occasionally cement is added to the mixture. The raw ingredients must be selected and mixed carefully. Once the forms are removed, the wall is very durable. Sometimes walls are covered with stucco. The forms can be fairly expensive because they must withstand considerable pressure as the sand/soil mixture is packed between them. Rammed-earth walls are termite resistant, but they tend to be labor intensive. So, unless someone is an owner-builder, these houses can be costly.
Adobe is made from soil having a sufficient amount of clay to hold the wall together well. Adobe is sometimes made stronger with the addition of straw or grass—or cement. The raw materials are not compressed like rammed-earth walls. Adobe walls are traditionally built up from sun-dried blocks. The blocks may require several months of drying time. The blocks are stacked up and held together with a mud mortar, and sometimes “plastered” with additional layers of mud. This type of construction is termite resistant but its use is limited to dry climates such as the southwestern U.S.
Straw-bale construction involves stacking bales of straw to form walls, then plastering or stuccoing the surface. Straw-bale houses are well-insulated, they use renewable resources, and they can have beautiful organic shapes. But, as with most construction techniques, there are disadvantages as well: straw-bale walls must be designed and built with care to allow for settling, stucco tends to be labor-intensive, and stucco can be costly. Tightly packed straw is remarkably fire-resistant and termite resistant. But it can become home to rodents if not properly plastered.
Moisture control is important in all forms of construction—green or otherwise. For example, adobe might not be appropriate in a rainy climate—unless you want muddy walls. Keeping moisture levels low in a straw-bale wall is very important to minimize decomposition. This isn’t to say that green technologies or alternative framing methods are more susceptible to moisture damage or fungal growth—its just that all methods of construction must address a variety of issues (e.g., moisture, infiltration, exfiltration, structural support, wind loading, air quality, longevity, etc.), and some of those issues may not be obvious to someone who doesn’t have an in-depth understanding of a particular system. So, if you are interested in a technology that isn’t widely used in your part of the country, you should get some expert advice.
Some green technologies are older methods of building that have been replaced over the years by conventional wood-frame construction, often because of cost—stick building with lumber tends to be less expensive. While some building codes are beginning to address some alternative techniques, they are often ignored in many jurisdictions. Plus, insurance companies, appraisers, and mortgage lenders don’t often embrace alternative technologies. And, in general, there is little evidence as to whether any particular approach is tolerated better or worse by chemically sensitive individuals.
