Bethlehem City Council unanimously turned back HARB approval of the exterior of a planned 5,000-square-foot addition to the Kemerer Museum of Decorative Arts on Tuesday night.

“This is not good enough for Bethlehem. This is not beautiful enough for Bethlehem,” said Councilwoman Karen Dolan, who led the charge to remand the museum’s “certificate of appropriateness” back to the city Historical and Architectural Review Board.

HARB is responsible for reviewing external alterations to buildings in the city’s Downtown Historic District. City Council has the final say on certificate approvals, but rarely rejects a HARB recommendation.

For the Kemerer and its parent organization, the Historic Bethlehem Partnership, the consequences of council’s rejection may be dire. A $3 million state grant issued for the project and smaller renovation projects of partnership buildings may be at risk if the new addition is not completed by November 2012, said Barbara L. Hollenbach, the museum chairwoman.

“I am somewhat taken aback by council’s actions this evening,” Hollenbach said. The museum, located at 427 N. New St., had hoped to have the project out to bid before the end of this year, she said. That now seems unlikely.

The proposed addition is a “collections resource center,” an archival building that will enable the Kemerer and the historic partnership to store 40,000 artifacts – some hundreds of years old – in a climate-controlled setting that limits light and humidity and its potentially damaging effects, Hollenbach said.

The building would be made of concrete, with no windows. It would be encased in a rubber membrane and covered with a rainscreen to prevent moisture from entering, Hollenbach said.

The space is needed to help the Kemerer and the historic partnership to preserve textiles, paintings, books and other delicate items, including a collection of 30 antique dollhouses, complete with miniature decorations made of paper, said Charlene Donchez-Mowers, president of the Historic Bethlehem Partnership.

Dolan said despite its 6-1 vote to recommend a certificate for the project, several members of HARB still had misgivings about the project.

Dolan took issue with the rainscreen exterior, which as proposed would give the appearance of a green-gray colored slate. While she said she understood that the rainscreen was a necessary feature for the archive, she believes the building’s external appearance could still be improved.

She issued a challenge to Historic Bethlehem Partnership supporters to open up their wallets to pay for a more aesthetically appealing façade.

“Perhaps the addition has not received the funding it needs to be of the quality it needs to be an addition to the beautiful, beautiful Kemerer,” she said.

Hollenbach said funding is not the issue, but the technical nature of the space required is.

The Kemerer has a long-range plan to build multiple additions as it acquires the funding it needs. Ultimately, new wings concealing its exterior would surround the archival building, Hollenbach said.

But to complete that project, the Kemerer would need between $10 and $12 million, not the $2 million it currently has to build a climate-controlled collections resource center, Hollenbach said.