Solar Convection or Passive House?
We are interested in building a home that is very energy efficient and we are working with an architect. He had given us preliminary drawings of a convection solar house. Does anyone have any experience with this type of home? Essentially, it has an area on the South side that acts as a heat collector – the sunspace. It is all windows and runs the length of the house but is only 8 feet deep. Then there is a full wall with windows and patio doors leading to the great room. We want tons of light and access to the outdoors. Does the idea of double walls eliminate the opportunity to see our woods and fields? The house also has a solar chimney with a damper that allows warm air to escape during the summer months. This is closed during the winter months to create a heating loop. Before we make this major commitment, we would love to be able to have a beautiful home that will be comfortable for us into our golden years, but is energy efficient, light and airy. Would a passive house fill this niche? Thank you!
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Replies
Margaret,
The type of house that you are calling a "solar convection house" was known as a "double-envelope house" in the 1980s. This design approach has been largely discredited. The energy savings, if any, attributable to the design are much too low to justify the capital cost of the required architectural features. Moreover, many of these designs were never built when building inspectors pointed out that the lack of fire dampers make the design dangerous.
An article in Environmental Building News on double-envelope houses noted, "The currently available data strongly suggests that the design underperforms expectations, while presenting additional concerns, including fire safety."
For more information on the history of passive solar design, I suggest that you read this article: Reassessing Passive Solar Design Principles.
The Passivhaus (or "passive house") approach makes much more sense, although many energy specialists have pointed out that the Passivhaus approach often requires very high levels of insulation -- insulation that is so expensive that the incremental cost of the required insulation is much more than can be justified by foreseeable energy savings.
Many designers and builders here at GBA favor a design approach called the "pretty good house" approach. For more on this topic, see this article: Martin’s Pretty Good House Manifesto.
For more information on the double-envelope house concept, see this Q&A thread: "We need some advice on a solar envelope house."