Princeton, N.J. — Planning for growth and changes at a university that has been around since the 1750s is surely daunting. But Ron McCoy, Princeton University’s new university architect, thinks starting from scratch would be even scarier. “I would be frightened at the tabula rasa opportunity,” he said here today at a conference called “Future Campus,” which is examining the planning and building of campuses all over the world.

Mr. McCoy and Mark Burstein, Princeton’s executive vice president, offered details on Princeton’s new campus plan, which will guide the renovation and construction of some 3 million square feet of space — growth that rivals the university’s expansion in the 1960s. The university worked on the plan with a number of consultants, led by Beyer Blinder Belle Architects & Planners.

Mr. Burstein said the plan deals with a series of problems and challenges on the campus: The approach from the south is not as attractive as it should be, as visitors pass parking ramps and a cogeneration plant. The university is surrounded by housing and shops, and any expansion must be sensitive to the scale of nearby neighborhoods. And like any university that has been around for more than 250 years, Princeton has a series of different architectural styles on the campus — styles that the university now hopes to unify.

As if those weren’t big enough challenges, the campus plan must also accommodate the university’s new focus on sustainability, Mr. Burstein said.

He said that Princeton had early on rejected the notion of expanding the campus to open farmland across nearby Lake Carnegie. That kind of expansion would harm the cohesiveness of a single, densely developed campus. But building more densely presents challenges in a campus environment. “Open spaces define a campus as much as the built structures on campus,” Mr. Burstein said. “How do we enhance the open spaces and densify as well?”

It turns out that greening the campus offers some solutions for the campus plan — which calls for pushing the forest into the campus and pushing the campus into the forest. The landscape projects are meant to reduce the impact of construction on the environment, particularly in stormwater management. The campus includes four tributaries that run into Lake Carnegie.

Green spaces will also help with the aesthetics of the campus. Since the 1960s, many open spaces on the campus have been marred by surface parking lots. A solution in at least one area is to push that parking underground and cover it with playing fields and green space. Greenery also helps convey a sense that the campus is built to human scale — especially with Collegiate Gothic, a style that suffers in larger buildings.

Toward the end of the presentation, Mr. Burstein talked frankly about Princeton’s sustainability goals and how those goals would fare in the plans of coming years. The university has set a goal of reducing its greenhouse-gas emissions to 1990 levels by 2020, and intends to do so without the use of offsets and other off-campus strategies. But at the current rate of growth, he said, the university’s emissions are forecast to be much higher than 1990 levels — even if all the new buildings and renovations are designed to be 50 percent more efficient than the building code requires. (Having conversations about efficiency with the star architects working on the campus, like Rafael Moneo, is a difficult process, Mr. Burstein said. He said a building by Michael Hopkins, a prominent British architect, will be 33 percent more efficient than the code requires as currently planned.)

The university will look to making changes in building systems to try to bring down its emissions — Mr. Burstein displayed a pie chart showing, in wedges and slivers, efficiencies that could be achieved by low-flow water fixtures, LED lighting systems, and state-of-the-art heating and cooling systems. But one of the biggest pieces of the pie was labeled “undetermined.” Mr. Burstein said that university is hoping that technology will come along that will help Princeton meet its goal.

He ended by noting that the campus plan will try to lay the groundwork for adding 3 million more feet after 2016. The next campus planners, he said, will have to worry over that. —Scott Carlson