“How much does your house weigh?” Buckminster Fuller asked in the 1920s, showing off his three-ton hexagonal Dymaxion House. He believed the technology used to mass-produce cars may as well be applied to houses, driving prices down and increasing mobility. Since then, many designers have wrestled with the size, cost, manufacturing and, indeed, heft of homes. In Superlight: Rethinking How Our Homes Impact the Earth (Metropolis Books, $35), Phyllis Richardson offers a global, contemporary perspective, highlighting recent projects from Chile to Vietnam. She also reconsiders what makes a project “light,” expanding the definition from pounds or kilograms to impact on the site, energy consumption (or generation) and the ability to cope with climate change. She spoke from London, where she lives in a Victorian house — with a polycarbonate and aluminum addition.