Law School students come and go from the newly-renovated Harkness Commons, their social space equivalent to Loker Commons, yesterday afternoon. Summertime renovations included an expanded lounge and new furniture.

Returning Harvard Law School students are buzzing about the $12 million transformation of their dark, unfriendly student center into a bright, welcoming social space.

The Law School hired Tsoi/Kobus & Associates, a Cambridge-based architecture firm, to renovate Harkness Commons over the summer.

The improvements to The Hark, as it is commonly called, include an expanded lounge and dining room, as well as new furnishings like leather chairs and restaurant-style booths.

“Everyone that I ran into at the beginning of the first week was like, ‘Have you seen The Hark yet? It’s unbelievable,’” said second-year student Krista H. Carver.

The Hark was intended to serve as a student center when architect Walter Gropius designed the two-story building in his trademark “function-over-form” Bauhaus style of architecture in the 1950s.

But students and administrators have said for years that the building’s sparse lighting, low ceilings and outdated décor actually discourage studying and socializing.

Law School Dean Elena Kagan said the majority of the $12 million went toward “deferred maintenance” because the building had been neglected over the years.

“It was terribly run-down, it was very dark, it was dingy,” Kagan said. “You went into The Hark and the first thing you thought was, ‘How can I get out again?’”

Kagan, who has described the former Hark as “an above-ground tunnel for light-allergic people,” said the basic structure of the building was retained but that the entire interior was redesigned.

She said the firm strove to preserve the building’s distinctive Bauhaus style, including a prominent ramp that leads up to the second floor.

“We basically did not knock down walls; we kept the essential structure of the building in tact. But beyond that, we really redid everything,” Kagan said.

The Hark now features a plasma screen for Law School announcements, student mailbox cubbies, an elevator, wooden floors, and up-to-date electrical, mechanical, audio-visual and air conditioning systems.

The sole student representative on the Physical Planning Committee, second-year student Molly M. Dunham, said students have embraced the new Hark as a “more relaxed alternative to the library.”

The major complaint she has heard is the removal of a foosball table. There has also been some “grumbling” about the downsized first-floor branch of The Coop and some faculty members were reportedly upset that their second-floor dining room had been taken away.

Dunham said parts of The Hark may eventually be converted to different uses. Last month, Robert A.M. Stern of Stern Architects, which will oversee the long-term development project at the Law School, said he hopes to incorporate the student center into a larger campus center.