In the midst of the late-1970s solar renaissance, a small number of experimental houses began to redirect the basic priorities of the movement by emphasizing "superinsulation" over solar heating. After the success of a few key prototypes, the superinsulated house became a legitimate challenger to the solar house.
By the mid-1980s, it could be claimed that "several tens of thousands of superinsulated houses were in routine use." "Solar vs. superinsulation" became a serious question for those interested in passive methods of reducing building energy use, and it remains so today (though the concepts are not mutually exclusive). Light-and-tight vs. mass-and-glass is another way of expressing this philosophical debate.
The history of superinsulated houses in North America began in 1976 with the Lo-Cal house at the University of Illinois. ("Lo-Cal" signified low-calorie, a clever bit of marketing which tapped into dieting fads popular at the time. Of course, a calorie is also a unit of heat.) The Illinois team, comprising architects and engineers, departed from the tradition of demonstration houses; they used early computer simulation techniques to create a series of prototype designs generally applicable to cold climates, and built a "test house" in Champaign in 1977.
With an outwardly unremarkable appearance, the Lo-Cal house kept its innovative features hidden: R-40 insulation in the ceiling, R-28 in the double-layer two-by-four-inch (five-by-ten-centimeter) walls, and R-20 in the floor. Wayne Schick, leader of the Lo-Cal project, is sometimes credited with coining the term superinsulation.
Saskatchewan Conservation House
The Lo-Cal design was much more opaque than the passive tradition, and the designers spoke of "sun tempering" rather than solar heating. Windows were triple-glazed, and 85 percent of the glass faced south. The design "corrects the deficiencies of the early solar houses," the researchers argued, by reducing the heat losses and eliminating the problem of summer overheating.
Ninety percent of the energy savings would come from insulation and very tight construction; 10 percent from solar gains. Ventilation was provided by an air-to-air heat exchanger. Schick called it "a totally integrated thermal-solar home." Though the researchers never built their design, as many as a hundred houses across the U.S. were built using Lo-Cal characteristics.
The most convincing and consequential demonstration of superinsulation occurred in Canada, where a group of engineers built the Saskatchewan Conservation House in the provincial capital of Regina in 1977. Building science expert Joseph Lstiburek remembers that the Saskatchewan Conservation House challenged the conventional wisdom of the time:
There wasn't a bunch of thermal mass and lots of south-facing glass in the house—no Trombe Wall, no tubes of water in the living room, no phasechange salts, no dark ceramic tile floors. It was just a house with boring technology—lots of insulation, airtight construction, controlled ventilation and not a lot of windows.
The walls measured R-40 and the ceilings R-60, levels approximately three times greater than the Canadian standard. Following the Lo-Cal principles, the structure included only a modest amount of triple-glazed windows—only 6.4 percent of the floor area—and R-30 shutters reduced nighttime heat loss. The project also achieved an unprecedented level of "tight" construction. In combination, all of these measures gave the house a heating requirement 1/28 of the average Regina house.
After a year, the Saskatchewan Conservation House did not need any auxiliary heat—never before had a building achieved "net-zero" heating in a truly cold climate. Despite the limited window area, direct gain provided 44 percent of the heat. The remainder came from internal gains, an air-to-air heat exchanger, and heat recovery from gray water. Evacuated tube solar collectors, to produce domestic hot water, were not needed for space heating, and the researchers later recommended omitting them.
The Saskatchewan Conservation House was probably the most successful demonstration house ever, anywhere, in terms of influencing a large-scale reduction in energy use. When it was opened to the public in January 1978, approximately 30,000 people visited.
As a result of the positive reception, the Canadian government launched the R-2000 program in 1984. This program offered $100,000,000 in performance-based incentives to promote superinsulation.
he first group of R-2000 houses consumed about 57 percent less energy than baseline standards, and the program (with refinements) remains active today.
Proving the Case for Superinsulation
The "boring technology" of superinsulation did not require years of scientific research, as demonstrated by Eugene Leger's 1978–79 house in Pepperell, Massachusetts. As a part-time homebuilder, Leger chose superinsulation after he studied many alternatives and concluded an active solar house would cost $15,000 more than a conventional house.
He basically followed the Lo-Cal principles: double-wall construction, small amounts of triple-glazed windows, tight construction with vestibules, and an air-to-air heat exchanger. He argued:
Any house that has to be fitted with solar collectors or huge amounts of south glass or that requires more than pocket change for heating fuel, simply wasn't designed properly in the first place.
During the winter of 1978–79 (a particularly cold season in the northeast), Leger's house used only $38 of heating, while his neighbors paid around $800. When it became clear that these superinsulated houses used "extraordinarily low amounts of energy," Martin Holladay recalls, "progressive builders and energy researchers throughout North America sat up and paid attention."
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An early champion for superinsulation was William Shurcliff, the Harvard physicist who catalogued solar houses. After Shurcliff studied the Lo-Cal, Saskatchewan, and Leger houses, he issued a press release in mid-1979 which argued for superinsulation as a "new category" with "a big future." He exclaimed: "Down with Trombe walls! Down with water-filled drums and thick concrete floors!"
Beyond performance, the superinsulated house stimulated a new aesthetic approach. Again, the solar house and the superinsulated house were not mutually exclusive categories, with some overlap in strategies, but in terms of architectural expression there were clear differences.
Shurcliff admired that superinsulation required "no weird shape of house, no weird architecture." The Lo-Cal prototype design resembled a more refined suburban ranch house, with some prairie-style influences.
Although the Lo-Cal methods did not have a prescriptive appearance, it was characteristic of the type that it "doesn't look spectacular." Likewise, Leger said: "I designed this house to fit into the neighborhood and not to jar anyone's sensibilities."
At the time, this attitude seemed refreshing to some. Lstiburek marveled: "The Leger House wasn't weird looking. It was normal looking. It looked just like your neighbor's house." The Saskatchewan house was an exception and perpetuated the association between energy-saving architecture and aesthetic eccentricity.
Even though superinsulation is technologically simple, economically proven, and aesthetically "normal," its influence in the United States has been limited. After a flurry of activity in the early 1980s, interest waned. These methods "hardly spread beyond a small band of dedicated custom-home builders," and even Canada's R-2000 program has been called "a boutique program that was pretty much ignored by mainstream builders."
There was not a dynamic public champion after Shurcliff. Although superinsulation remains an excellent energy-saving technique today, the most recent book on the subject was published in 1985.
Meanwhile, according to Holladay, "American builders completed tens of millions of leaky new homes, most with two-by-four-inch (five-by-ten-centimeter) walls haphazardly filled with fiberglass batts." To be fair, the superinsulated house probably had a greater effect on energy codes and the housing industry than the solar house. In any case, Lstiburek recently observed: "In the United States... we're not building a lot of efficient houses…. We all know what to do, but we can't seem to do it."
Today, the influence of the superinsulated house persists most significantly in the Passivhaus movement. German physicist Wolfgang Feist and Swedish professor Bo Adamson conceived the Passivhaus standard in 1988 after studying Shurcliff's accounts of the Saskatchewan and Leger houses.
"The basic idea of the Passivhaus concept," Feist wrote, "is to improve the thermal performance of the envelope to a level that the heating system can be kept very simple."
In other words, the standard promotes high insulation values and supertight construction. (The term Passivhaus is problematic, as Martin Holladay notes, because the houses are not passive; they require active space heating and ventilation systems.)
Feist built the first Passivhaus, a four-family housing block, in Darmstadt-Kranichstein in 1991. It expressed a Bauhaus-like rationalism, with large south windows and virtually opaque east and west walls. (The north side included an unheated greenhouse buffer zone.) It used 85 percent less heating than an equivalent building meeting German national code.
Then in 1996 he founded the Passivhaus Institut, which administers the voluntary standard. Feist and his team evaluated 221 Passivhaus units in five European countries in 2005 and found a total energy savings of 80 percent. As of early 2012, there were over 1,700 projects registered in the Passivhaus database, the vast majority located in Germany.
In addition to a super-insulated building envelope, the Saskatchewan Conservation House employed a solar hot water collector, heat recovery ventilator (HRV), and a grey water system with a heat collector. Photo: Courtesy Saskatchewan Archives BoardExtra Large Image
The Yanagimachi Solar House II (1958), in Tokyo, Japan, was designed by Masanosuke Yanagimachi to be super-efficient in a semi-tropical climate while also respecting a traditional Japanese residential aesthetic. Photo: Courtesy University of WyomingExtra Large Image
The U.S. Department of Energy's Solar Decathlon, occurring every two years, is a competition intended to foster and showcase energy efficient residential design. Shown here is the Appalachian State University entry for the 2011 competition cycle. Photo: Jim Tetro/ U.S. Department of Energy Solar DecathlonExtra Large Image
Although no requirement mandates the architectural style of the Solar Decathlon homes, their floor area must be kept between 600 and 1,000 square feet (between 56 and 93 square meters). The Solar Homestead by the Appalachian State University team is a 833-square-foot (77-square-meter) home. Photo: Jim Tetro/ U.S. Department of Energy Solar DecathlonExtra Large Image
Clad in wood boards and corrugated metal, the Solar Homestead comprises four modest structures organized around a porch shaded by the building's 8.2-kilowatt photovoltaic array. Photo: Jim Tetro/ U.S. Department of Energy Solar DecathlonExtra Large Image