At first, the three-story, 2,300-square-foot red-brick rowhouse in Fishtown seems to be an ordinary early-20th-century rowhouse — until you notice that there's no front entrance.

Instead, there's a wide front window surrounded with what look like hand-constructed details and a narrow window created out of the former doorway. The entrance, it turns out, is around the side of the house.

Maura DiBerardinis, who owns the house with her husband, Peter Angevine, answers the door with baby Arlo in her arms. She explains that the entrance was moved so the former door could provide needed light into the living room.

The couple bought the house three years ago and moved in May after the building was gutted and reconstituted as a passive, energy-efficient house by architect Jeremy Avellino of Bright Common Architecture.

A violinist who teaches in a Philadelphia public school, Maura is the daughter of Michael DiBerardinis, managing director of the City of Philadelphia, who lives across the street.

"I have always loved the neighborhood, and we jumped at the opportunity to buy the house because my parents are my best friends, and we can help each other," Maura says. "We have huge family dinners every Sunday, and our house requirements were a large space to host the dinners that will expand because there are now 16 people, and more grandchildren will probably be coming."

Other requirements for her family, Maura says, were a backyard and an ecologically responsible home.

Avellino, aided by Juan Levy, a passive-house contractor, fitted the house with three-pane windows, airtight connections, cellulose insulation, and an electric heat pump system.

"The result is low energy use," Avellino said. "This project is important because it could be repeated across so many row homes throughout the city to help reduce climate change."

Both musicians, Maura and Peter devote most of their cream-colored front room space to various instruments. Peter, who runs Little Baby's Ice Cream, a company based in East Kensington that's committed to sustainable agriculture and waste reduction, used to be in a band and still plays when he can.

"We have a Wurlitzer keyboard, xylophones, harmonicas, drums for my classroom, as well as string instruments," Maura said.

Above the instruments is a trapezoid-shaped "wunderkammer," or "cabinet of curiosities," a feature popular in Renaissance Europe. Maura and Peter use the space to display artwork of friends.

The well-lit first floor has an open plan, created by removing walls. It includes a combined golden yellow kitchen, dining room and hall. In a corner of the kitchen, a shelf of ethnic cookbooks represents cuisines from around the world.

"I love to cook, and we have a lot of dinners here," Maura says.

A newly configured teal-and-yellow stairway not only leads to the second floor, but also brightens the long narrow kitchen and hall.

On the second floor is the family's living room, with a comfortable brown leather sectional filling about a quarter of the room. The walls are painted one of the varieties of medium blue used throughout the house. A floor-to-ceiling bookcase adorns one wall.

Peter, who "loves the neighborhood," says the positive environmental qualities of his house add to the reasons he and Maura want to live there.

"We decided to put our money where our mouth is and do something for the environment and not just talk about it," he said.