It's become chic in certain circles to know your carbon footprint, but few ultragreens know what they're missing. The calculators that tally an individual's contribution to global warming rarely take account of materials that go into our homes and offices. Factories that make concrete, drywall and foam insulation are big carbon sources. Cement (a component of concrete) accounts for 5 percent of global carbon emissions.
Some new building technologies are emerging as potential alternatives. Geopolymer cements, a byproduct of steel and power plants, and a non-gypsum alternative to standard plasterboard for drywall could cut emissions by at least 80 percent over traditional materials because they can be made at relatively low temperatures. Ecovative Design, a firm in Troy, New York, has developed a carbon-neutral, biodegradable insulation that could replace energy-intensive foam panels made from polystyrene or polyurethane. The technology is based on an organic resin extracted from mushrooms. Time (and regulators) will tell whether these technologies merely serve niche markets or cut the true size of our carbon footprint.