The Hermans have been very interested in the idea of “aging in place,” living in a home that is comfortable and livable, but designed with the future in mind: they might need to make it accessible for ramps, wheelchairs, etc. To meet their aging in place goals, stairways would need to be widened, and all doors would be at least 36” wide, to accommodate wheelchair access.

But to them, the future isn’t just about themselves and the possibility of failing bones and joints—it is about a healthier future for their grandchildren (and our world), which means limiting the burning of fossil fuels, reducing waste, conserving water, and managing stormwater onsite—to name just a few of the issues their home addresses through its design and renovation.

How did their journey begin? In 2014, they found a 107-year old Victorian home on a small city lot in Minneapolis. Serendipitously, Stewart had stopped by a Home and Garden Show, where he heard about the concept of a “net-zero energy” home. Having been intrigued by renewable energy since the energy crisis in 1973, he told me, “When I learned about Net Zero Energy homes, a light bulb went on.” Could they remodel an existing home such that it would not contribute to climate change? The next year of design and two years of construction proved that they could. 

Unique Features of the Home

Typical to most net-zero energy homes, this old Victorian was retrofitted with all LED lights, triple pane windows, and efficient, ENERGY STAR appliances. No gas appliances are in the house, eliminating the need for combustion venting and keeping the indoor air quality healthier (the code-required carbon monoxide detectors will never be triggered). What is not typical is that this home was a remodel—so several innovative ideas needed to be incorporated. Below, we share a few highlights, excerpted and slightly modified from Stewart’s “Innovations” Flyer he wrote himself to share his knowledge.

2.    Making the house “tight” while controlling moisture.

Much heat and moisture are lost through leaky walls. This house was wrapped in a sticky membrane made by 3M, which prevents moisture from becoming trapped and causing mold or rot. Forty percent of the insulation is inside the 3M barrier, and moisture will evaporate back into the living space, where humidity averages a comfortable 40 to 45 percent. The other sixty percent of the insulation was outside the 3M barrier but inside the Tyvek barrier. Air (and moisture) are allowed to circulate freely under the siding without entering the house. The result is that the house is almost five times tighter than building code requires, and practically meets the Passive House standard.

4.    Making a roof fit for solar panels. 

The original 1907 house had a “balloon” frame constructed of slender 2″x4″s—not suitable for solar photovoltaics (PV). The Hermans added a new roof of plywood I-beams on top of the old roof. The space between the I-beams was filled with 10 inches of foam insulation; combined with the 6 inches of fiberglass batting under the old roof, they were able to insulate the roof to R-80. The roof supports 42 solar collectors—weighing one ton in all. Supporting all this new construction is a massive laminated ridge beam, which workers installed by hand. They added another 12 solar collectors on the detached garage, resulting in a 17-kilowatt solar photovoltaic array that produces more electricity than the house consumes (hence, “Net Zero”).

5.    Getting hot water fast.

One lament of people who live in old homes is that they must run the faucet a long time to get truly hot water from their centrally located water heaters. A small pump was installed to recirculate a loop of hot water, in insulated (R-4) pipes, so that hot water is never more than a five-second wait in the bathroom faucets.

6.    Saving energy by recycling heat. 

In most homes, it’s amazing how much heat is wasted out of the vents. In this home, the heat exhausted from bathrooms, and the kitchen is used to warm incoming outside air through an Energy Recovery Ventilator (ERV). Also, all excess heat from the geothermal heat exchanger is used to pre-heat the domestic hot water. Both of these efficient technologies help decrease the amount of energy needed to heat and cool the home and the water. (Note that a geothermal heat exchanger was not an easy install for a retrofit, with only 30x40 feet backyard. While they were not sure if they could even get a rig in there, they ended up putting in 4 wells 10 feet apart, each at 250 feet deep.)