For the first time, the Fairfax County Planning Commission has approved a plan by a county agency to buy an apartment building to save it from condominium conversion.

At a meeting last week, the commission authorized the county Housing Authority to buy the Greenwood Apartments at Seven Corners and convert it to a cooperative, if requested federal officials indicated they expect the funds to be released within the next few months.

The Housing Authority hopes to purchase the building for $3.6 million, and has asked the federal government for the entire amount.

Under the Housing Authority plan, the current tenants -- primarily low- and middle-income families -- will be allowed to remain at the new coop, and eventually purchase their apartments.

The move is regarded by many officials as unique in state where few regulations exist to restrict condominium conversions. County officials, said they were faced with a crisis -- the possible of conversion of the complex and eviction of present tenants -- and had no recourse but to act.

"This was a crisis situation and we realized the Housing Authority had to take some action," said Deidre Coyne, a spokeswoman for the Housing Authority. "If the condominium conversion had proceeded as planned, most of the tenants would not have been able to buy their units, and therefore, forced out into a very tight housing market."

The planned conversion of the 153-unite complex first came to the Housing Authority's attention last spring when tenant representatives approached the authority for help. The agency decided to intercede and apply for public housing funds when it appeared no other solution could be found. Fairfax Supervisor Thomas M. Davis III (R-Mason), who worked on the acquisition proposal, said the housing agency had two choices: Buy the building or let it go condo.

"Virginia is a different political animal from states like Maryland that have strict condominium conversion rules," Davis said. "It is much more conservative. When a guy wants to convert there is nothing we can do to stop him. This time, through the concerted efforts of a lot of people we were able to pull it off and will probably get federal money that would otherwise have gone to some place like Akron, Ohio."

No state or local funds will be involved in the purchase, according to Coyne. However, federal funds are expected to be available to buy the building and, after the purchase tenants will be eligible for a federal subsidy program which will help them with monthly payments.

Housing officials said plans to convert the fbuilding to co-op using federal funds is unusual.

"There are few instances in the country where federal public housing funds are used to form a co-op," said Coyne. "Usually, subsidized housing involves straight rentals."

Under the plan, residents will "lease" their co-op units, making a payment every month. The payments will go toward the building mortgage. Once the mortgage is paid off, resident s will own the building, according to housing officials. Unlike a condo, residents will not own their individual units, but will own shares in the co-op association. Residents will not be required to make down payments.

The monthly payments will vary according to the salary of the tenants, but under federal subsidized housing guidelines, payments can be no more than one-fourth of a teenant's monthly income. In the Washington area, Coyne said, a family of four cannot make more than $19,450 to qualify for the subsidized program.

Coyne added that she expects monthly payments to be less than present rents, which range from $280 for a one-bedroom unit to $325 for a two-bedroom unit.

Some of the current tenants may exceed income limits, but Coyne said housing officials are trying to work out an agreement with the federal government to allow most, if not all, current tenants to remain.

Coyne said the Housing Authority opted for cooperative ownership rather than a subsidized rental complex for a variety of reasons.

"The residents will have a degree of control that they would not have under a rental situation," Coyne said. "Living in a co-op will give the people an opportunity to exert control of their living environments.

Plans for the complex include a $10,000 renovation of each apartment.

Although tenants and county officials greeted the purchase approval with relief, most said it represents only a minor and momentary suspension of the county's housing crunch for low- and moderate-in-come citizens.

This is just a drop in the bucket when compared to need," said Coyne. "If the Fairfax County government and housing authority wants to save more lower-priced housing units from condominium conversion, then it will require resources -- monetary and legislative -- that we presently do not have."