It is as true of houses as it is of human beings: What’s on the inside matters most.

Dan Magraw and Lucinda Low’s Potomac, Md., two-story brick and vinyl siding Colonial was completely transformed by a year-long remodel by Landis Construction of Washington. But little about the 1967 vintage home appears changed—and that’s just what the couple wanted. “We didn’t want to lose the history of the house,” Low explains.

What the couple sought was a house that worked. They particularly wanted an energy-efficient remodel, a fitting request from Magraw, who ran the international environmental law office for the Environmental Protection Agency between 1992 and 2001. He pushed to have a geothermal system installed, as well as solar panels and beefed-up insulation. And Low sought to bring lots more light into the dark corridors of the 8,000-square-foot home.

The house had numerous comfort issues. To say that it was in need of an energy redo was an understatement.