The Stahl House was the 22nd in a series of designs sponsored by Arts & Architecture magazine from 1945 through 1966 and known as the Case Study Houses. Not all the designs were built, but collectively they served as a central arena for architectural experimentation.
Pierre Koenig's Case Study House #22, the Stahl House, as it appeared in a 1960 photograph by Julius Shulman. The house is on the US National Register of Historic Places.
As a fan of midcentury modern design, I knew about the Case Study Houses. What I didn't realize—until I read an article in the January issue of Technology and Culture—was that the experimentation in some of the designs included passive solar heating.
The T&C article that enlightened me was "Tomorrow's house: Solar housing in 1940s America" by Daniel Barber of the University of Pennsylvania. Barber notes that a confluence of factors brought passive solar heating and modern architecture together in the years immediately after World War II, when the suburbs expanded to house a growing population swelled by discharged soldiers, sailors, and airmen:
As the technological and financial aspects of homeownership began to take on new implications for economic growth and social stability, design strategies of architectural modernism—including the expansive use of glass, the open plan and façade, and the flexible roof line—were seen as a means to construct a suburbia that was sensitive to emerging concerns over materials allocation, energy resource scarcity and the economic challenges to postwar growth.
British architects, I learned from Barber, had investigated passive solar heating a decade earlier to encourage cost-effective rural building during the Great Depression. A 1931 study commissioned by the Royal Institute of British Architects demonstrated that insolation—a term coined by the study—could in principle be used to heat suitably designed buildings. In practice, however, the all-glass façades of the prototypes proved to be insufficiently insulating.
The L-shaped living quarters of the Stahl House wrap around a swimming pool.
Even the advent of double glazing in the mid 1930s did not improve the insulating properties of passively heated houses. Indeed, Forbes recounts an experiment conducted from 1944 through 1947 by F. W. Hutchinson of Purdue University. Hutchinson had two small houses built that were identical but for the extent of their windows. Despite letting in more sunlight, the glassier house was significantly colder in winter.
As the 1940s wore on, the need to conserve energy and building materials waned whereas the need to house America's growing population persisted. Mass-produced tract houses became the suburban norm, not elegant, passively heated glass houses.
But research, development, and deployment of passively heated houses continued. Perhaps their epitome is the concept of the passive house, which originated in the 1990s in Darmstadt, Germany. Built to exacting standards, passive houses rely on heat exchangers, formidable insulation, and stringent air-tightness. Although they cost 8–10% more to build than normal houses of the same size, they cost almost nothing to heat.
I'm intrigued by the idea of living in a passive house, but somewhat put off by the need to keep the windows tightly closed, which would remind me too much of my modern, climate-controlled office. But if, like the Stahl House, the passive house came with outdoor living space, count me in.