Buyers dreaming of going off the grid can virtually tour 16 solar homes

Just as CV-19 has thousands of Coloradans reimagining where they want to be living, the crisis has some of those people thinking seriously about solar and renewable energy — building or remodeling to generate more of your own energy, at a moment when people are officing from home much more than in the past. Solar pioneer John Avenson has been watching the interest in solar skyrocket the past few months; and today he and other members of non-profit New Energy Colorado have a way for you to get serious about those ideas.

This weekend is the 26th Annual Metro Denver Green Homes Tour — this year a virtual event featuring 16 homes around the area, including one Avenson showed me this week, ten miles up Golden Gate Canyon Road.  Martijn and Beth van de Rijdt had dreamed about creating a net-zero home for a pretty property backing to Centralia Mountain; and they made that happen in 2018.

Check out this 2,000-sq. foot design to see how far solar has come over the past 40 years:  It has the core features of passive solar—more glass on the south to let sun in, less glass on the north; with roof shading to keep the sun out in summer, and lots of interior mass to store heat. Many houses were built like that in Denver and the foothills during 1970s-80s when solar was hitting peak popularity; but a tech revolution in energy conservation, ventilation, and back-up heating allows homes like this to go way beyond what was possible back then.

Starting with insulation:  The van de Rijdt house has double 2×4 walls that allow insulation levels that were only done in ceilings a few decades ago — so high, says Avenson, that the incremental addition of even more insulation doesn’t change the equation much. On this home, the backup heating is a hybrid hot water tank that heats kitchen and shower water but also supplies radiant heating through the concrete floors to boost the solar heat they’re storing. The van de Rijdts have a bank of solar electric panels on the hill behind the home that provides all of the back-up; and a network of pumps and air exchangers that sends heat around the house to deliver fresh air and keep the system from running too warm.

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