Greener homesFor much of human history, homes were built to make the most of the sun, air, and water. For much of the last century, however, home builders assumed that cheap fossil fuels could provide artificial light, heat, and breezes. This zero-net-energy Mission District dwelling in San Francisco is lauded as one of the world's "greenest" residences.That's changing, as everything from high-rise condos to bungalows are being renovated or built from scratch to make smarter use of natural resources. Off-grid and zero net energy homes are no longer solely the domain of hippies.Green Homes for Sale lists off-grid and other dwellings scattered throughout North America. This scorecard describes pollution levels in U.S. neighborhoods. EcoBroker-certified realtors help clients understand greener options. Modern Green Living lists green communities, architects, builders, and remodelers. "Green" construction products, such as lumber certified by the Forest Stewardship Council, and paints low in volatile organic compounds, are common in the aisles of Home Depot. Green Label Plus describes carpeting low in toxic chemicals. Consumers Union's toxic search tool connects to descriptions of hazardous chemicals in the built environment. The Building Materials Reuse Association directory finds companies that repurpose architectural artifacts and waste from construction sites.Indoor air can be more toxic than air outdoors. Using cleaning products with fewer fumes, such as from "green" companies like Seventh Generation, can help to clear the air. Clorox Greenworks and SC Johnson's Greenlist products are available in more stores. Or, you can make your own eco-cleaners. Vinegar, for instance, can polish windows. A lemon cut in half with salt poured on top can scrub a sink.The Pesticide Action Network North America database describes toxins in bug-killers, as well as less harmful alternatives. Some companies are concocting pest-fighters that use solar power or that interfere with the critters' hormones. However, one theory argues that colony collapse disorder among honeybees could be caused by "greener" pest control products that interfere with insects' neurology.