Light streamed into a gleaming new ballroom Thursday morning as University of Massachusetts Boston leaders opened the academic year with a celebration of the school’s unprecedented growth.

But that growth, and the sparkling new buildings rising on campus, are coming at a cost.

UMass Boston faces a $22.3 million budget gap that has brought higher tuition, cuts to about 100 adjunct professors, and fewer classes this year. Festivities Thursday were marked by student and faculty protesters who said the university has thrust its financial problems onto them.

UMass Boston — a top destination for local students — is in the midst of major campus renovations to transform the campus and its academic reputation.

But several construction projects have been plagued by unexpected setbacks that will cost the university extra millions. A new parking garage will cost $71 million instead of $45 million, and an underground utility project will be $233 million instead of $177 million, UMass trustees learned this week.

College leaders acknowledge they are in difficult times but said the challenges, like the construction dirt all over campus, will be temporary while the benefits long-lasting.

“This time is so momentous, this time is so dramatic in the history of our campus that the familiar line about the winter of our discontent came to mind,’’ Ellen O’Connor, the campus’s vice chancellor of administration and finance, told the roomful of staff, faculty, and students at the convocation. “And to acknowledge the truth to you, this will also be the autumn of our discontent and next spring we’ll have plenty of discontent, too.’’

O’Connor said payroll costs are driving the growing deficit, which was $3.5 million in 2015 and has now reached $22.3 million. The campus’s overall budget is around $426 million.

Most campus employees receive about a 4 percent annual salary increase and the cost of fringe benefits has also grown, she said. So has the amount of money the school gives in scholarships. A memo from O’Connor in January called Boston an “outlier’’ among the five UMass campuses in terms of its budget gap.

To address the problems, UMass Boston Chancellor J. Keith Motley has appointed a special budget committee that will make recommendations soon.

At Thursday’s convocation, Motley also defended the university from critics who still think of the Columbia Point campus as a small commuter school. UMass is in the process of building its first-ever student dormitory, which will hold 1,000 students and is expected to open in fall 2018. Enrollment has grown during the past decade, to 17,000, although the campus struggles to retain students.

“We’ve been undermined and doubted for more than 50 years,’’ Motley said in his one-hour speech, sometimes pacing across the stage.

The chancellor said he has heard some say UMass Boston’s success adversely affects the private schools in the city. He said that’s a good thing. “We ought to raise eyebrows and make people take notice,’’ he said.

Later the ballroom filled with protestors who came to hear the keynote address by state Education Secretary James A. Peyser. They questioned the Baker administration’s support for public higher education.

Students and professors held signs that said “When you raise tuition, you fail the urban mission,’’ and “Education is a right,’’ and “Cuts hurt these students most: first generation, working class, homeless, single parent, low income, and others.’’

In July, the UMass board voted to raise annual in-state tuition to $13,110 thisyear, an increase of $750. Peyser, who is also a UMass trustee, voted against the tuition increase, saying the university should do more to find savings before passing the cost to students.

Peyser gave a 17-minute speech that described his view of public higher education, then took three questions, facing heat from protesters who asked why he won’t fight for more state funding for UMass.

“We’re doing the best we can,’’ he said.

Peyser said public higher education needs to not just balance its annual budget, but fundamentally change its model. The state’s 29 public colleges and universities should find efficiencies by working together and turning out graduates with degrees that match job openings.

After his speech, protesters flooded outside to a rally where Massachusetts Teachers Association president Barbara Madeloni told the crowd of about 150 that she was “chilled’’ by Peyser’s comments. Taking issue with the secretary’s use of a quote by Henry Ford, she said it implied that he thinks “the university is a kind of like an automobile factory.’’

While UMass Boston was the main focus, Madeloni and Boston City Councilor Tito Jackson also used the convocation to rally against a ballot initiative that would lift the state’s cap on the number of charter schools. Peyser has been a vocal supporter of the initiative.

Other speakers lamented the loss of the UMass Boston adjuncts this year. Marlene Kim, an economics professor and president of the Faculty Staff Union, said professors are worried about the trajectory the cuts may signal.

“We need new buildings, but we also need faculty and we also need to keep the university affordable,’’ Kim said.

Students at the rally worried the university will lose sight of its mission to educate urban students. They cited an influx of international students and the new dormitory, which they anticipate will bring students from afar.

“I see less and less students who look like me and that’s a problem,’’ said Sadie Barbosa, who is black and a senior in African studies.

Laura Krantz can be reached at laura.krantz@globe.com. Follow her on Twitter @laurakrantz.