A Zero Carbon Home on the National Solar Tour

As a hint of fall temperatures finally arrived over the nation’s capital during October’s first weekend, the American Solar Energy Society (ASES) and Solar United Neighbors hosted the National Solar Tour on the 5^th and 6^th. This year, over 800 homeowners in 45 states opened their homes to visitors and shared their decision to “go solar.” They described their experiences with financing, selecting a contractor, and assessing system performance. According to ASES and Solar United Neighbors, more than 400 organizations, installers, and non-profits helped organize and conduct the event across the country.

Professor Sklar and his students touring his zero carbon home.

One of the homes on this year’s tour belongs to Scott Sklar, an adjunct professor at George Washington University where he teaches sustainable energy courses. He is also president of the Stella Group Ltd (a clean energy technology and optimization firm), and a member of EESI’s advisory board. Scott’s home in a leafy neighborhood in Arlington, VA, is a complete embodiment of the concepts he teaches his students. Scott draws no power from the grid. His home is a zero carbon building—highly efficient, and using only renewable power. Scott employs a variety of technologies on the property to produce more electricity than he uses, and stores the balance in batteries so he is never without electricity, for both his home and back office building. The Professor makes the point to his students that before installing solar panels or other renewable sources, it is critical to first make the home or building as efficient as possible. That is exactly what Scott did when he bought the house in 1985.

Solar panels and a solar hot water heating panel on the roof.

The house was built in 1921 as a Sears kit bungalow. When Scott moved in, he added a second story, insulated the upper floor and attic to R-38, and installed highly-insulated windows and other conservation measures. He uses ENERGY STAR® appliances and LEDs for lighting. The addition doubled the size of the house, but his energy retrofits cut the average energy use from 5.4 Kilowatts to 3.2 KW. To generate energy, Scott installed solar panels on his south facing roof, and another roof panel for solar hot water heating. His small, two-story office building behind the main house is powered by solar shingles. At night, when solar is unavailable but the wind picks up, electricity for the office is generated by a wind turbine fixed atop a monopole beside the building. Scott insulated the office addition to R-50, uses only solar day lighting for both floors, and LED lighting at night.

Solar ink “mini solar panels” on the awning power WiFi and LED lights.

Over the walkway that connects the main house with the office is a plexiglass awning partially covered with photovoltaic nanotechnology films. An inkjet printer applied solar ink in strips to the film. The ink strips function as solar panels and produce enough electricity to power WiFi for the walkway and LED lights that illuminate the path at night.

For heating and cooling, Scott uses a direct exchange geothermal heat pump. This ductless system circulates refrigerant through an air handler and heat exchanger in the house to underground tubes transferring excess heat from the house in the summer to the cooler constant 55^oF ground, and drawing in heat from the ground in winter. This geothermal system requires 67 percent less electricity than conventional air conditioning. Ceiling fans throughout the house and office also reduce air conditioning costs. In his office, to augment summer power requirements during tropical storms when it is hot, hazy, and humid with thick clouds, Scott uses a 2 KW hydrogen fuel cell to generate power for battery charging. The electrochemical reaction in the fuel cell that produces electricity emits only water which he uses to irrigate a tree in the back yard.

Scott (left) discussing his demo van with home tour visitors.

Parked on the street in front of Scott’s house are two vehicles he owns, a 2010 Toyota Prius with a solar array built into the roof (Toyota no longer offers this option on Prius models sold in the United States), and an educational van he drives to universities in the area. The van is retrofitted with solar panels, a wind turbine, and a battery bank that together power a DVD and an all-weather video screen on the vehicle.

Professor Sklar’s home, surrounded by a tree canopy in Arlington, VA is an example of how we can use existing tools and technology to conserve and sustainably generate the energy we use in our homes and buildings. Climate change is here now, but so are solutions we can employ to counteract the crisis. Scott and other homeowners on the Solar Tour are showing us the way forward.

Author & Photographer: Jeff Overton

For Scott’s biography, and additional details about his home visit Stella’s site: www.TheStellaGroupLtd.com