Located at the corner of Church and Elm Streets, the 18-story First Niagara Bank Building has moved into the hands of prominent local developer Paul Denz.

Northside Development Company, of which Denz is president, announced Tuesday that it will purchase the property at 195 Church St. for $18.25 million. Denz said he plans to redesign the commercial facade of the first and second stories of the building, create a new lobby and, perhaps most notably, provide flexible office space for tech companies and implement an energy efficiency plan. As a part of the deal, which is expected to close by the end of the year, the First Niagra Bank will remain in the building under a sales-leaseback agreement.

“We want to make 195 Church St. the first choice for new tenants coming into the New Haven market while creating a more attractive space for existing clients,” Denz said in a statement.

Economic Development Administrator Matthew Nemerson SOM ’81 voiced excitement for the upcoming developments, noting that the purchase effectively acts as an investment in the city.

With the addition of the First Niagara Bank Building, Northside Development now owns a number of buildings downtown. Included are 91 Church St., which houses Five Guys Burgers and four upscale apartments, and 832 Chapel St., where construction on 100 apartments will begin in late 2016, according to Northside Development’s website.

Denz also owns the Exchange Building, located on the same block as the First Niagara building, which the company purchased for $2.7 million in 2013.

First Niagara, which purchased the building in 2011, originally put it up for sale last December, with the intent of leasing the building from the buyer. First Niagara spokeswoman Karen Crane told The New Haven Independent in December that the bank intended for operations to remain in the building, and that the 130 workers at the location would not be affected by the building’s impending deal.

In an interview with the Independent, Denz said the bank would remain in the first four floors of the building for a decade, but would relinquish space in the three floors above those. The bank laid off nearly 200 workers at the end of last year in Connecticut, Massachusetts, New York and Pennsylvania, along with closing down over a dozen branches.

Jeff Hubbard, New England region president at First Niagara, said in a statement that the bank believed in having a local owner to ensure a viable future for both the building and its tenants.