In an unusual application of the urban renewal program, hundreds of futuristic homes are being stacked on top of each other along the rocky hillsides of a 370 acre wooded site in Northwest Baltimore, about 10 minutes by car from downtown.

The project, called Coldspring, has never been advertised or promoted by a real estate broker. Yet 180 families are trying to but the 124 units currently avilable.

The buyers are black and white and primarily porfessional, according to M. Jay Brodie, Baltimore's housing commissioner and head of the city agency that inspired the project. Some occupants are migrating from the suburbs and some from other parts of the city. They range from families with children to retired persons and "empty nesters," the name given to couples whose children have grown up and left home. Brodie himself intends to move into Coldspring.

It is not Coldspring's purpose to replace tired slum buildings with sleek high rises and town houses Nothing but forests and meadows have ever existed on the site.

But to Baltimore's housing commissioner, Coldspring is indeed "renewal" as a new, efficient, manageable, safe and attractive community that he hopes will lure middle income residents back to the city from te suburbs of surrounding counties.

Coldspring, designed by "Habitat" creator, Moshe Safdie will house 11,000 residents when finished.

In the first phase of the "deck" style condominiums, prices range from about $33,000 to 60,000 for two to four-bedroom brightly lit multi-tiered homes. The first occupants move in next month.(See COLDSPRING, B3, Col. 1)(COLDSPRING, From B1)Eventually. Coldspring will also contain modernistic cluster-style homes stacked in and on top of the rolling hillsides and a high-rise complex built down into the 250-foot depths of a drained rock quarry like old-world cliff dwellings.

Neighborhood commercial areas and a large "town center" with recreational and day-care facilities and nature trails will be spread across the mile-long site between Cylburn and Druid Hill parks in Baltimore.

"I don't like the 'new-in-town' nomenclature often given Coldspring because the title seems to have aspirations of an autonomous entity," explained Brodie. "Coldspring is part of an existing falric of the city. It shouldn't attempt to be self-sufficient. We won't try to satisfy every human need with it."

In Coldspring, land use is efficient Parking spaces are tucked under stacked houses which are, in turn, built into and on top of hillsides to avoid bulldozing the rolling landscape into boring flatlands.Walkways connect one end of the community to the other without forcing pedestrians into streets.

All this means more open space than most large-Scale projects--roomy grassy plots or outdoor decks for every condominium, one acre of parkland for each acre of housing and a sizable window planter with every unit.

It is a balance between community and privacy," said Safdie, the Coldspring architect reknown for his "Habitat" development in Montreal's Expo 67. Habilat, which Safdie designed at the age of 26, showed it is possible to combine the advantages of concentrated city living with suburban privacy and the out-of-doors

Safdie said he had been thinking for many years about low to draw on contempoarary lifestyles for design rather than simply relying on pleasing architectural styling. "Habitat was a building not a community, and I was becoming more interested in how to do a whole community," said Safdie.

In 1970, the Montreal architect was asked by Baltmore's former housing commissioner. Robert C. Embry Jr.now an assistant secretary in the U.S. Department of Housing and Urban Development, to take a look at the site that city officials had assembled for Coldspring.

"It had everything going for it." said Safdie. "It created a good environment for itself. It wasn'kt like going into a city disastrously slummy. I was very excited."

Safdie came up with a plan that blended three interrelated aspects he believes are essential for successful urban housing in the U.S.

"Socially, the community must be built in an area people will feel comfortable in - where they'll feel safe, have a good school, for example," hes said.

"Financially, if you price yourself out of the market you fail and that creates a predicament between quality housing and what people can afford. Architecturally, you have to design something which are not necessailty the same things."

Sensible economics and sensible planning in an era of many failures in grandiose new urban housing experiments were crucial. Brodie emphasized.

"I can safely say that today it is impossible to build reasonable quality middle income in-city housing in the U.S. without some measure of public support," Safdie added.

Of the $200 million cost, $150 million has come from private capital generated by developer F.D. Rich Co. of Stamford, Conn., and the rest from federal urban renewal money. Baltimore taxpayers will not be asked to spend a penny on Coldspring, but Baltimore voters have approved a revenue bond sale that will insure mortgages for potential buyers of Cold spring condominiums CAPTION:

Picture 1, Moshe Safdie, architect of Montreal's Habitat, is designing Coldspring in Baltimore;Picture 2, an unusual project of cluster-style condominium houses;Picture 3, and a highrise complex located on a hilly, wooded, 370-acre site. By Douglas Chevalier--The Washington Post; Map, X locates Coldspring project.