Funding Berkeley and Branford college renovations was easy.

But the Yale Office of Development is working overtime to secure funds for the renovations of Saybrook and Timothy Dwight colleges and Vanderbilt Hall. As campus renovations continue, University fund-raisers are finding it tougher than before to excite potential donors.

The approximately $40 million renovation of Saybrook College is underway, but fund raising totals still fall short of the $20 million the Development Office hoped to raise by this point. Similarly, only $5 million has been raised for TD so far, which is slated to be renovated next year and will be the most costly of any college project thus far.

The development office succeeded in procuring $20 million for the renovations of Berkeley and Branford colleges one year before either of the projects was underway. That luck has not held with more recent projects.

The development office is targeting alumni of the colleges for donations to fund renovations.

Last March, Saybrook alumni Holcombe Green Jr. ’61 and Joshua Bekenstein ’80 donated a combined total of$10 million to the renovation of their college. To galvanize other potential donors, their gift functioned as a matching challenge — all donations between $25,000 and $1 million qualified to be doubled with funds from Bekenstein and Green’s contribution.

Despite the two Saybrugians’ generosity, 10 months have passed and only $16 million have been fund raised for the college’s renovation. And Vice President for Development Charles Pagnam said he wants to raise even more than the projected $20 million because costs of the renovations will be higher than expected.

“I don’t see a $5 million dollar gift on the horizon,” Pagnam said. “We hope to secure $1 million gifts and have it done by February.”

Yale President Richard Levin said he recently secured “a substantial commitment” for Saybrook, the details of which he would not disclose. He said the University will make a special effort to reach out to Saybrook alumni at this year’s spring reunions.

Raising the necessary funds for TD may prove even more difficult than for Saybrook because that project is more expensive; it includes the renovation of Rosenfeld Hall, TD’s annex building. The college itself will cost $42.6 million and Rosenfeld Hall will be an additional $10.1 million.

Pagnam said the development office is trying to secure a “leadership gift” — or one major donation to spur more gifts — for TD. He added that Levin spoke with a potentially big donor Wednesday.

Officials have said there are a handful of TD alumni who are in a position to give a substantial amount of money to the college. Regardless of how much money is raised before next year, University officials said they are fully committed to begin TD renovations this spring.

“I’d like to have my part done by the time the old mattresses in TD are thrown out in May,” Pagnam said. “But that would be overly optimistic.”

Following the TD renovations, the University will break its cycle of renovating a residential college each year and instead overhaul Vanderbilt Hall on Old Campus, which will cost $17 million.

Officials said it is hard to predict how successful fund raising efforts for the Old Campus dormitory will be. Because it is not a residential college, Pagnam and his staff do not have the usual suspects to turn to — the particular college’s alumni.

“We may have to use direct funding from the operating budget,” Levin said.

But Pagnam said the development office plans to look in records to find people who lived in Vanderbilt and will also target alumni believed to be “particularly fond of Old Campus.”