When he took office last year, Dean of the Faculty William C. Kirby pledged to increase the size of the faculty by 10 percent over the next 10 years.

Summers said a second option for undergraduate housing in Allston—building three Houses to replace those currently in the Radcliffe Quad—also would require far more discussion.

“I have heard people say that it would make a more integrated campus, a more integrated Harvard Square area,” he said. “But whether that’s a good idea or not a good idea—at this point there are certainly many, many questions of cost associated with it.”

Moving the Quad was a possibility discussed by the University Physical Planning Committee, the Allston planning group that presidential adviser Dennis F. Thompson led. That committee considered land adjacent to the river where College athletic buildings are currently situated as a possible location for new Houses.

Though the announcement this fall may not address the question of undergraduate housing, it is likely to kick-off an intensified debate on the equally thorny question of what sciences could be built in Allston.

David A. Zewinski ’76, a FAS planner, has said that life sciences will likely move, and Summers himself, though publicly noncommittal, questioned Friday whether there is space for FAS science to expand in Cambridge.

Asked whether some FAS science would inevitably have to move to Allston, he said, “I do think there are very important long-run issues for the University to ensure we have very substantial space for science building and scientific laboratory space, and we need to recognize the realities of the planning.”

Once a “focus” is announced this fall, Summers said, Harvard will be able to undertake more extensive financial, architectural and academic analyses of the viability of moving any specific part of the University.

—Staff writer Elisabeth S. Theodore can be reached at theodore@fas.harvard.edu.