become a burden on the developed economies. This situation has encouraged some positive changes in building over the past two decades, but mainstream practices change slowly, and there are also powerful interest groups that are still driving open-ended material development. The modern green building movement had its origins in the appropriate technology movement of the sixties. The oil shocks and energy crisis of the early seventies launched a new solar and energy-efficient building industry. Throughout the seventies the new industry of consultants, designers and builders evolved from an initial focus on active solar technology, to passive solar design, and eventually to superinsulated construction, as there was an emphasis to make energy-conscious building more mainstream and affordable. The dramatic appearance of massively daylighted passive solar structures (which also often included giant greenhouses and masonry or water-drum thermal storage) gave way to the modest almost windowless boxes of the super-conserver variety. But many of the new super-sealed boxes of the late seventies and early eighties also were plagued with moisture-condensation and air-quality problems. This called greater attention not just to ventilation, but to the building materials that were outgassing toxic fumes. These concerns with the toxic composition of materials gradually dovetailed through the eighties with growing environmental concerns about global warming and the embodied energy of building materials (the energy it takes to produce the materials), and also with the crisis of municipal landfill spacewhich focused concern on the recycling of building materials. By the early nineties, disciplines of life cycle analysis were attempting to quantify the total environmental impacts of building materials, and