Soon after they became empty-nesters, Shari and Jan Almquist devised a plan for this new phase of their lives. They would sell the too-big turn-of-the-century house in Swarthmore, where they raised their daughter, move into a Center City apartment, and buy a beach house for weekend getaways.

Then, one day, just as they were having qualms about the high price of real estate in Cape May, their beach town of choice, Shari Almquist saw a for-sale sign go up on an unusual home just down the street in Swarthmore.

Built in 1915 as the town telephone exchange, the two-story building had once housed rows of operators tending tall banks of switchboards during the era when phone calls were put through manually. Converted into a home in the early 1950s, the place was graced with high ceilings and lined with windows (20 of them) that measured 6 feet tall by 4 feet across. It had great bones, as architects like to say.

And that's how the couple ended up scuttling their original Shore plan, moving just three blocks east, and embarking on a major redesign and renovation project that gave a funky old building a sophisticated contemporary edge.

"We call it our suburban loft," says Shari Almquist.

When the Almquists took their first close look at the property, though, it wasn't exactly an inspiring sight. The front and back yards were overgrown, and English ivy blanketed the structure, obscuring some of the windows. The Vermont slate roof was in need of repair. The aged electrical wiring needed replacing, and so did the hulking old oil heating system, which had pipes thickly swathed in crumbling asbestos.

The layout, too, was peculiar. The first floor was a rabbit warren of tiny rooms, while the walk-out ground floor (with a door to the backyard) featured a utilitarian kitchen and a ceiling full of low-hanging heating pipes.

"I said, this is going to be a lot of work," says the initially skeptical Jan (pronounced Yon). What helped sell him on the place was the truss roof. "Before we bought it, we had a builder come in and take a look to make sure we could take down walls without putting up partitions or columns," he says. This was key, for the couple envisioned a grand, open space - combining kitchen, dining room, and living room - that would take up nearly half of the 75-foot-long, 25-foot-wide building.

Also part of the big plan: installing a geothermal heating-and-cooling system, with all new ductwork. The new system, which gets top ratings for energy efficiency, draws on the Earth's relatively moderate and constant temperatures, and it required two 300-foot-deep wells to be drilled in the narrow driveway.

"The contractor said he had never drilled in such a small space before," says Jan. "But if I could not have done the geothermal, I would not have bought the place. The only way I was going to do this renovation was if I could do it green. If I'm not going to live in the city, I want to create a smaller carbon footprint."

The Almquists, who made settlement on the house last June and moved in August, accomplished a lightning-fast renovation by acting as their own general contractor. Jan, a graphic designer and a partner in Allemann, Almquist & Jones, an Old City design and communications firm that specializes in brand strategy and visual identity for companies and organizations, served as the architect as well, preparing all of the drawings himself. (He also did some of the finish carpentry.)

Along with taking down walls to open up the first-floor space, the redesign included reducing the number of bedrooms to two (plus a sitting room) and creating a new central hallway, which features a soffited ceiling with indirect lighting built in. Cut high into the hallway walls are rectangular open transoms.

"The transoms let light into the hallway and allow the heating and cooling to flow," says Jan, whose striking black-and-white photographs decorate the walls.

In the sunny new open-plan living space, a baby grand piano has center stage, the province of daughter Maja (pronounced Maya), a Skidmore College junior come September and an accomplished pianist. The modern kitchen features a Cararra-marble-topped island and dark-wood cabinets - some of them hung horizontally without doors as a clever spin on open storage. The refrigerator is a German-made Liebherr, a model that is cheaper and more energy efficient than a SubZero, say the couple.

Also helping to give the space a distinctive contemporary feel is a pair of charcoal-gray sofas designed in the late 1950s for Spectrum by Dutch designer Martin Visser and still in production. The sofas, whose backs flip down to convert to sofa beds, feature brightly colored upholstered cubes as movable armrests.

To connect the space to the outdoors, the couple replaced one of the eight-over-eight double-hung windows with a massive glass door that leads to a newly constructed mahogany deck. The deck, whose wood-slat sidewalls are set at three different levels, has a treehouse feel and is one of Shari Almquist's favorite features. "When we're up here, no one can see us. It just feels so private," says Shari, a metalsmith and gemologist, who met her husband when both were art students at the Philadelphia College of Art (now the University of the Arts).

Part of the couple's green sensibility during the renovation included leaving well enough alone. Downstairs, they left the old kitchen intact (anticipating using it for parties) and outfitted part of the space as a media room. On the main floor, they refinished the original Douglas fir floors and gave those old windows a boost in energy efficiency with the help of triple-cell cellular shades as window coverings. Also left mostly untouched, save for the installation of a Toto high-efficiency toilet in one, were the two tiny original bathrooms with their vintage tile.

"We like old things," says Shari. "We didn't see any reason to fiddle with them."

Asked if she missed her old home, a sprawling Shingle-style place with a big front porch and a whimsical rooftop cupola that Jan designed and had built, Shari smiles and says decisively, "Not at all. It was too conventional for me.

"We like having one big space when we have people over," she says. "And I really like the light here."

"It's so nice to get up in the morning and walk into this room," says Jan, who doesn't pine for the extensive gardens and big backyard of his former residence, where the couple hosted games of bocce ball on the lawn.

Now, he's got a compact cottage garden up front and, in back, just a tiny circle of grass ringed by a shade-plant border he's been busy cleaning up. "It's a lot less work," he says. "I like the simplicity of this place. It's about efficiency."