When the owners of a historic single-family home in Old Town approached local interior designer Lukas Machnik, their instructions were threefold: Design a place that was aesthetically pleasing, suited for kids, and as eco-friendly as possible. “The clients are strong believers in making the future better for children by being responsible and conscious about what they put into the environment today,” says Machnik of the family, which includes three kids, a stay-at-home parent, and a parent employed by a global environmental organization. “And [the parents] are very down-to-earth; they want to spend time with their family,” he explains. “So it was important to [be] functional, not pretentious, and use every corner, every space.”

The result of the project—Chicago-based firm Hartshorne Plunkard provided the architects—is a two-story, five-bedroom, four-and-a-half-bath house complete with basement theater, library, rooftop deck, and backyard patio. To comply with the historic restrictions in the neighborhood, the architects kept and restored the front wall, but built a more contemporary addition in the back. Machnik’s design could best be described as Danish minimalism, employing green building materials and technologies such as tankless water heaters, a green garage roof, and sustainable bamboo floors.

The green ethos extends to the furniture as well. Machnik designed the dining table, which was built by woodworking company Birger Juell from pin oak that was salvaged from Terre Haute, Indiana. Machnik maxed out the size, providing ample space for the family of five to spend time together. “Everyone can gather here; the kids can do homework; they can have dinner with the whole family.”

With function in mind, Machnik included several pieces that serve double duty. The custom fireplace in the living room also acts as a buffer to create a designated foyer area and provide additional privacy from the giant glass entry doors. The guest room, adjacent to the rooftop deck, doubles as a convertible cabana-style space that can open up to the outdoors, and the maxed-out garage not only houses standard storage items but also can morph into an extra entertaining area. “The big barn doors can open up, so when you have an event or party, you can set up a bar or catering station there,” says Machnik. As for the rest of the yard—which includes the adjacent lot—Machnik provided a table and chairs for the patio, which looks out to an open lawn for the kids’ activities. “I like that you’re entertaining the adults, but you’re still with the kids,” he says.

A “spend here, save there” balance is one cornerstone of Machnik’s approach, and accessible items include World Market lanterns hanging in the guest room and Ikea furniture in the kids’ rooms. “Kids outgrow things all the time, and the furniture just gets abused,” he says. But size doesn’t always equal splurge. “Sometimes it’s more about the quality of the piece,” he says, pointing to the bronze vases by Rick Owens as an example.

The family, frequently on the move due to the parent’s profession, are thankful that Machnik was able to meet their needs during their Chicago residency. “We want our kids to be able to play, do messy art, and be exuberant,” says one of the parents. “I told Lukas to design something beautiful that we could also ride a bike through and hose down. He did it.”