A House Tried to Save Sunshine in Salt

On Christmas Eve 1948, Mária Telkes’s cousin, his wife, and their three-year-old son moved into a new house in Dover, Massachusetts, without a furnace. A tall bank of glass and black metal faced the low winter sun. Behind the rooms sat ducts, electric fans, and drums of Glauber’s salt. The family had agreed to live inside a full-scale wager: sunlight gathered during the day could be saved for a New England night.

The Dover Sun House was the work of three women. Telkes, a Hungarian-born biophysicist and inventor, designed the heating system. Boston architect Eleanor Raymond gave the machinery a house. Sculptor and philanthropist Amelia Peabody financed the project and supplied a site on her estate. Telkes had pushed salt-based heat storage at MIT, where an experimental installation performed badly and she was reassigned away from the solar project. Rather than leave the argument in a laboratory, the three built an occupied home.

Collecting heat was the straightforward part. Eighteen tall glazed panels along the south-facing upper story trapped sunlight against black-painted metal. Fans moved the warmed air into three storage compartments filled with containers of sodium sulfate decahydrate, commonly called Glauber’s salt. At roughly 90 degrees Fahrenheit, the salt melts while absorbing a large amount of energy. That energy changes the material from solid to liquid instead of simply making it hotter. When the house cools, the salt is supposed to crystallize and release the stored heat back into the circulating air.

The chemistry was elegant, and Raymond made it determine the building’s appearance. From outside, the collector resembled an oversized strip of dark second-floor windows. The living rooms remained below, while the equipment occupied the thick zone above and around them. The solar machine became the façade instead of arriving later as hardware attached to an ordinary roof.

For two winters, the house appeared to prove its point. The family lived without a conventional furnace, reporters arrived, and thousands of curious visitors toured the building. Popular Science suggested the experiment could prove more consequential than the atomic bomb. LIFE photographed Telkes in a fur coat beneath the glass collector. She understood that an unfamiliar technology needed an image people could remember, and the sharp, wedge-shaped house performed that job extremely well.

The salt was less cooperative off camera. As it repeatedly melted and cooled, it separated into liquid and solid layers instead of returning evenly to its original state. Each cycle left less material able to store heat properly. The metal containers also corroded and leaked. Fans consumed enough electricity to weaken the fuel-savings claim, and long cloudy periods sent indoor temperatures down until the family needed portable heaters. During the third winter, the system broke down. An oil furnace eventually replaced it.

The expensive lesson sat in the gap between a useful chemical property and a durable building product. Solar heat arrived, and the salt could store it. The system could not repeat that performance reliably through years of imperfect weather, moving air, electricity use, corrosion, and maintenance. Hydrated salts remain a subject of thermal-storage research, but modern work treats container stability and repeated cycling as central engineering problems rather than minor details to solve later.

The Dover Sun House correctly identified storage as the hard part of solar architecture decades before rooftop panels became ordinary. It also showed why a convincing prototype has to survive contact with residents and winter, not merely a calculation. The glass wall made the future easy to photograph. The leaking cans decided whether anyone could live in it.