By 1972 Reynolds had sold his first house -- the Thumb House -- erected out of these beer-can “bricks.” Then, around 1973, shortly after the first energy crunch, Reynolds started trying to build thermal mass into his experimental houses. “I was already playing with garbage as a building material, and I saw that there were mountains of automobile tires all over the country,” he says. “I discovered by trial and error that I could beat dirt into them and create a massive wall that stored energy and made it so that you had to use less heat in your house because the heat that you did put in got stored into the walls.”
Subsequent tweaks to his concept came about as newer problems were addressed by the media. Reynolds and his company also added a photovoltaic-electricity option following the energy crunch. When water shortages were predicted, they began designing the houses to catch, filter, and store water underground -- for bathing and washing first, watering interior greenhouse planters second, recycling it for flushing toilets next, and finally, for watering plants outside the building. They addressed excess sewage and pollution by making the houses contain and treat their own sewage on-site. And their newer houses also have greenhouses. Reynolds boasts that each home’s utility costs run less than $100 per year.