The common origins of Superinsulation, Passivhaus, and Net Zero homes

A lot of valuable lessons were learned as a result of the oil crises of the 1970’s. Unfortunately in the 1980’s many of the conservation initiatives from the 70’s were abandoned – but the skills, knowledge and awareness garnered at the time were not lost, and we’re benefiting from them today. In building science big strides were made in insulation and air sealing of houses, and a lot of this knowledge came out of two projects in Illinois and Saskatchewan.

In 1976 a group at the University of Illinois at Urbana-Champaign developed a design which they named the “Lo-Cal” house, which used two adjacent stud walls, with alternating studs, to achieve R30 insulation and eliminate thermal bridging through the framing. The term “superinsulation” was coined by Wayne Schick, project leader, to describe the high insulation levels used in the walls, attic, and basement. Several houses, duplexes  and condos based on the Lo-Cal design were built in Champaign-Urbana, Illinois between 1977-79.

The Saskatchewan Conservation House was built in Regina in 1977, using similar principles but went further with R40 walls. Again the walls were built out of two stud walls, and the extra 10 insulation points were gained by adding a cavity between them. The whole wall assembly was filled with blown-in cellulose insulation. Another thing that these two projects had in common was a science-based approach, with extensive modeling of the designs, and monitoring of real-world performance.

One of the most important things that both the Saskatchewan and Illinois teams learned was that in most houses the heat is simply slipping through the cracks, and they needed to develop techniques to dramatically increase the air-tightness of buildings. When they realized they were removing all the natural / accidental ventilation from the house, the Saskatchewan team created one of the world´s first air to air heat exchangers, or heat recovery ventilators (HRVs). There´s now a global market for HRVs, and in most cold climate areas some type of air sealing is now required by building codes. In Canada the creation of the R2000 system (a voluntary system for building efficient homes) was credited to lessons learned from the Saskatchewan Conservation House.

The lessons of sealing and air exchange have been widely adopted, but the idea of superinsulating a house to R40 or above, or emphasizing passive solar heating, have remained relatively on the fringe. One of the people who noticed the Lo-Cal and Saskatchewan Houses was Wolfgang Feist, the originator of the Passivhaus standard – a very rigorous system of building that is popular particularly in Europe where there are some 20,000 certified passive houses. Feist lists Harold Orr, an engineer who worked on the Saskatchewan House, as one of his influences. And it’s probably no coincidence that Urbana-Champaign, origin of the Lo-Cal house, is one of the centers for the passive house movement in the United States.

Rob Dumont, one of the engineers who worked on the Saskatchewan House, went on to build his own house in 1990, which at the time was the most highly insulated house in the world. Surprisingly, the extra insulation, upgraded windows, and a solar thermal heating system, only added about 7% to the building cost. “If I´d put brick on the outside of the house instead of siding,” says Dumont, “the brick would have cost more than all of the energy conservation features. I´d much rather have an energy-efficient house than a brick house.” In fact, the energy efficiency finished paying for itself in 2008, after 16 years – now it´s all gravy.

Conrad Nobert, owner of the Mill Creek House in Edmonton had the same experience with cost. “We got 80 to 85 % of the way to net zero, versus a conventional home, for about 20 to 25 thousand,” says Nobert. “So you would call that a net 0 ready house.” When Conrad talks about net zero, he means that the house will produce as much energy as it uses, by balancing energy use with energy production from solar panels on the roof. It sounds easy – just keep adding solar panels until you reach net zero – but in fact very few houses have enough room on the roof, or even on the property, to compensate for the energy they´re using for heat and electricity. The Mill Creek House uses similar systems to the Saskatchewan House, only better – it has double stud walls, spaced 16´´ apart to get R60 walls, an advanced HRV, and triple glazed windows that are R8.

Peter Amerongen, who built the Mill Creek House, credits his career as a builder of super-insulated houses to a talk he attended about the Saskatchewan House. “I heard Harold Orr in 1978 and it just stopped me in my tracks,” says Amerongen. Ever since then, Amerongen has been building R2000 or better homes. Before building his first net zero house, Amerongen went on a pilgrimage to Rob Dumont’s house to learn what he could from it. Then he took it even further.

Likewise the Passive House movement has gone far beyond its inspiration of a few superinsulated homes built during the late ’70’s. But the original superinsulated homes should not be forgotten, if nothing else for their simplicity and affordability, as evidenced by Rob Dumont’s 7% incremental cost to build the world’s (then) most highly insulated home. What that tells me is that we should be building all our homes to a much higher standard. And I’m sure that change will continue to happen, slowly. Meanwhile the Passive House and Net Zero homes are the pioneers that we can look to for examples of how far we can go.

More information about the Lo-Cal House can be found in a presentation by Michael McCulley.


  1. […] Conservation House; he was involved in the invention of the HRV and blower door tests, and his work influenced the Passive House and Net Zero movements. Now in his eighties, his brain is a library of energy efficient building, and he talked to me for […]

  2. […] but the house, like Dumont himself, is understated. Dumont took the double wall system from the Saskatchewan Conservation House, stretched it out to a full 16 inch wall cavity, and filled this space with blown-in cellulose […]

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