The Cambridge Rent Control Board voted last night to force Harvard to refund approximately $4000 in extra rent that tenants of 8 Plympton St. paid because of an error in the board's calculations.

But the board refused to address the controversial issue of differences in rents for businesses and for residential units occupying the same building.

"The board really dodged the central issue," Michael H. Turk, Harvard Tenancy Union Coordinator, said after the meeting adding. "They slammed the door on it."

In January of 1981, an error in the rent board's space formula resulted in an inadvertent overcharge of tenants in 8 Plympton St. a building containing both residential and commercial units. The board failed to evaluate properly the difference between the commercial rents and the residential rents.

Retroactive

The rent board acknowleged its error in March 1982 and lowered the rents in the building. But one tenant, Anne Brinton, said Harvard should have to refund the difference between the rents.

The ruling last night resolved the controversy in the case of 8 Plympton St. But by not addressing the issue of commercial and residential rents, the board failed to set guidelines for other mixed buildings.

"As it stands now, the landlords come out ahead," Turk said Businesses in the Square now pay enormous rents and have no organization to protect their interests he added.

Last Chance

Because the board had detailed figures for 8 Plympton St. it could have used this case to set a precedent. Turk added, in similar cases where there was no related controversy over rent refunding, the financial figures would not have been available.

But Harvard Real Estate's attorney, Danile Polvere, said yesterday he thought the board had considered this matter with great care.

The rent board recently came under a similar criticism from one of its members for refusing to take a stand on a controversial issue Earlier this week, landlord representative Sally Ackerman faulted the board for failing to set guidelines that would equalize treatment of landlords regardless of the number of buildings they own an issue sparked by the recent controversy over the proposed renovations of the Harvard owned Craigie Arms apartments.