Before the special ventilation system is installed, the solar water heaters added, and the insulated windows are fitted at a new set of super-efficient homes in Washington, D.C., the foundation must be laid and the wooden bones erected. Last month, several of us from National Geographic arrived to help do part of that work as volunteers for Habitat for Humanity.

The six row houses being constructed by Habitat for Humanity, a Great Energy Challenge grantee, will be passive homes, which means they will be specially insulated and have a much lower energy footprint than the average home. The construction site lies on a residential street that, like much of Northeast Washington’s Ivy City neighborhood, is a place in transition. A vine-covered, abandoned school built in 1911 serves as the imposing bookend on a line of older houses amid several new ones that are either completed or under way, built by Habitat for Humanity and reserved for low-income residents.

When finished, each home will be enclosed in a “thermal envelope” so well sealed that it will be able to maintain a year-round internal temperature of about 70 degrees Fahrenheit (21 Celsius) with a minimum of supplemental heating and cooling. That means residents will have utility bills up to 90 percent lower than they normally would be, resulting in a monthly savings of more than $100 a month, according to Habitat estimates. The homes will “breathe” via an ERV, or Energy Recovery Ventilator, which helps keep the inside air fresh and regulates the temperature.

The group receives instructions before beginning work at the Ivy City construction site. (Photograph by Christina Nunez)

The group receives instructions before beginning work at the Ivy City construction site. (Photograph by Christina Nunez)

Savings like this on heating and cooling, significant for a low-income household, can be meaningful for a home at any income level. After all, the largest percentage of energy use in the average U.S. home—48 percent—is for heating and cooling. That represents a decline over the last 16 years, the U.S. Energy Information Administration notes, thanks to more efficient homes and a population shift to warmer climes, but the energy expended to keeping a home’s temperature comfortable is still significantly ahead of the second-biggest, and steadily growing, share of home energy use: appliances, electronics and lighting.

Our group of 16 volunteers spent the day erecting scaffolding and bolstering the wooden frame of one of the houses. Joining us were Yenealem Sata and his wife, Aselefech Gebrie, a couple with three children originally from Ethiopia. In order to buy the home at its below-market rate, Yenealem and Aselefech will put in 300 hours of “sweat equity,” among many other requirements. (The home’s price will be $270,000; after subsidies from the D.C. Department of Housing and Community Development, the buyers will finance $200,000.)

The homes' wooden frame will eventually be surrounded by a thermal envelope that regulates temperature and minimizes the need for additional heating and cooling. (Photograph by Christina Nunez)

The homes’ wooden frame will eventually be surrounded by a thermal envelope that regulates temperature and minimizes the need for additional heating and cooling. (Photograph by Christina Nunez)

All of us at the site took direction from the site’s construction foreman and experienced volunteers from AmeriCorps, who guided us through the basics of buzz saws and scaffolding assembly. Despite frigid temperatures earlier in the week, the weather that day was sunny and comparatively balmy, getting into the 40s.

The work was muddy and challenging, but the primary mood among us seemed to be gratitude. We were grateful that it was 40 degrees outside and not 15, grateful to trade (if only for a day) the intangibles of email and web pages for the tangibles of metal and lumber, and grateful for the chance to make the link between what we do inside the National Geographic headquarters with real results outside it.

The passive homes in Ivy City are due to be completed in early spring of 2015, and the Great Energy Challenge has stationed a camera at the site to capture construction. Stay tuned for further updates.

Volunteers from National Geographic at Habitat for Humanity's Ivy City project site (Photograph by Jason Kurtis, National Geographic)

Volunteers from National Geographic at Habitat for Humanity’s Ivy City project site (Photograph by Jason Kurtis, National Geographic)