A passionate builder and author took his knowledge to the mountains of Colorado in a very successful experimentation in how to make a passive home in such a dynamic climate with cold temperatures and a lot of sunshine. Based on his experience, he was able to create a symphony of material combinations in the right ratios - like only 20 percent glass facing south - to create the most energy efficient home in Colorado.

The process of certification with PHI though the Passive House Academy took some time but went relatively smoothly. To my surprise, we beat the energy threshold by almost two times. This turned out to be great news as the home is only powered by solar electricity and has a small propane hydronic heating system. The home’s main heating source is the sun, followed by the “waste” heat of the occupants and appliances, and then finally a small hydronic heating loop in the wall and at the Heat Recovery Ventilation system.

The home has been occupied for a year, and while it uses practically no energy for heating, the real take away is how comfortable it is. The house tends to naturally hover between 67 and 77 degrees Fahrenheit without heating or cooling. I use the heating system sparingly, so during a recent cold spell, when exterior temperatures reached -10 degrees, I let the house get down to 62 degrees. After taking a shower, I was surprised that it did not feel chilly like in most houses.

Why? What I learned in high school physics class paid off. The heavily insulated building envelope reduces heat loss through conduction, but it turns out that ambient air temperature is not the only reason we feel comfortable or not. With such a tight and well-insulated envelope there is neither cold air coming in nor interior air circulating by cooling convection. But what really makes the difference is the radiantly neutral surfaces, especially the triple pane glass. My bare (and damp) skin does not bleed heat via radiation to cold surfaces, which in turn reduces the need for extra layers.

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