Fifty years before the term “carbon footprint” came in vogue, MIT held a symposium titled “Space Heating with Solar Energy.” Three women were on the 98-person registration list.

Scientists at the August 1950 gathering warned of dire situations familiar to us today. Eugene Ayres, a solar expert with the Gulf Research and Development Company, wrote in his paper’s abstract, “We know that time will come when we shall require a consciously engineered plan for solar energy utilization instead of simply burning up everything we can burn as rapidly as we can find and produce it.” He went on to outline the peak of the United States’s coal production, forecast oil being depleted within a century, and noted the possibility of having to import our fuel needs from abroad.

Embedded in this conference was another revolution: the opening of the field to women. Clippings from newspapers covering the event point to the persons who most captured the public’s interest: the “woman scientist” and “woman architect” who built the Dover House, a $10,000 house heated entirely by the sun. The scientist and the architect were Maria Telkes, an MIT researcher in the department of metallurgy, and Eleanor Raymond, who was based in Boston.

A decade before the women’s liberation movement began, one newspaper crowed, as if surprised, “Woman Scientist Collaborates with Woman Architect to Design Dwelling.” Two days later, another paper parroted the startling news of the participants’ gender: “The house of the day after tomorrow is on the way. In fact one already has been built … and another, much less expensive, is envisaged by a woman scientist and an architect of the same sex.” In the following days, news of the women who “hope to have home heated by sun” flew from Salem, Massachusetts, to London, England.

The Dover House, constructed in 1948, was funded by Boston sculptor Amelia Peabody and located in Dover, Massachusetts. It was the only solar house in existence heated solely with solar energy. MIT also exhibited a solar energy house at the conference, but because it relied on a method of solar heating in which water was the basic heating fluid, the house used auxiliary heat during sunless days. Telkes relied on a sodium salt of sulpheric acid called “Glauber’s salt,” which stored heat at seven times the efficiency of water.

Telkes’ system blew air between panels of glass and metal heated by the sun. These solar panels sat directly behind a bank of eighteen windows that lined the second story of the house’s south-facing wall, which was a story higher than the north-facing wall. The house itself was wedge-shaped, the roof deeply slanted. Raymond loved the beauty of functionality found in rural American structures; to collect the necessary amount of light, the handsome structure looked like a typical home chopped in half, its windows as eyes peering toward the south to capture the sun’s warmth.

The warmed air from the solar panels traveled through a duct and across storage bins. The bins, enclosed and insulated within the walls of the house, were filled with 21 tons of Glauber’s salt. The salt melted at 90 degrees Fahrenheit and stayed melted for a long time. While it cooled and recrystallized, the salt gave off the stored heat.

Telkes’ house effectively solved the heat-storage problem of solar heating systems. On cloudy days, when no solar energy was entering the system, heat from the cooling, recrystallizing salt circulated throughout the house. Telkes had analyzed data from the National Weather Bureau and found that the longest stretch Boston had gone in 65 years without sun was for 9 days. She calculated the amount of salt she needed in order to heat her house through a sunless period and came up with the 21-ton figure required for 10 sunless days. Despite her house’s success, Maria Telkes was quick to assure her audiences that “no one house could be successfully set down in another locality where climate, surroundings, and family demands would be different.”

Still, the sun—no other form of energy—heated the Dover House for three full winters before a system failure ended the experiment. After all, as Telkes told listeners at the 1950 symposium, “the problem of the sun-heated house cannot be solved by one or two experimental houses. But each new house is another experimental stepping stone toward the use of the sun as a fuel resource.”

Neither of the women constructed another solar house. In 1953, Maria Telkes left MIT to establish a solar energy lab at New York University. There, she continued work on solar heating systems, ovens, and portable water distillation units. She was given the first-ever achievement award bestowed by the Society of Women Engineers in 1952, and ended her career teaching at the University of Delaware. Eleanor Raymond was made a fellow of the American Institute of Architects—a prestigious achievement—and enjoyed a fifty-year career.