Rents for office buildings in the United States declined 41 percent in the last four years when calculated in real terms, a real estate study showed this week.

"Although a particular building may not be affected, the national trend shows a substantial decline in the real rents that landlords are realizing in office buildings," said Stephen E. Roulac, president of a San Francisco real estate advisory firm.

Roulac's study, published in the December issue of the Questor Strategic Real Estate Letter, calculated real rent by making adjustments for vacancy rates, rent concessions and inflation.

The number of landlords facing a drop in real rates could be substantial, because between 60 and 80 percent of office leases are adjusted to the market rate every three to five years, Roulac said.

"This isn't to imply that the value of every office building is dropping or will drop," Roulac said. "Those buildings that are fully leased on a long-term basis may be largely unaffected. However, near-term cash-flow projections are way down for those buildings with many short-term leases near expiration, a factor of major importance to possible purchasers."

Roulac said the increase in concessions to tenants is a major factor in lowering the real rates of rentals. These concessions result from "the dramatic increase in office vacancy rates in recent years," he said.

The Maryland Department of Economic and Community Development is providing nearly $26.8 million in low-interest financing for construction of an apartment complex in Silver Spring.

The money will be used to build the Chase Ridge Apartments, a 16-building complex with 432 rental units at Rte. 29 and Briggs Chaney Road. The state agency said 51 percent of the units will be set aside for tenants with limited incomes.

Construction of the units is expected to help alleviate the tight rental market in Montgomery County, the agency said.

Groundbreaking will take place next spring, and builders expect to complete the three-story garden apartments within 18 months.

The state agency has provided more than $579 million in financing for 17,542 units in 135 complexes throughout Maryland since the market-rate rental housing development program began in 1982.

Residential construction in Ocean City would be significantly restricted under a proposal sent by the city's zoning board to the mayor and City Council.

The seven-member Planning and Zoning Commission voted unanimously this week to recommend zoning changes designed to ease future congestion on the island.

If the changes are passed by the mayor and council, the number of residential units allowed on a parcel would be decreased by as much as between 30 and 45 percent in the city's most densely populated districts. The recommendation was made after two years of debate and three public hearings.

A number of citizens -- most of whom are retirees and year-round residents -- argued for drastic reductions in the number of units allowed on a lot. The residents claimed many of the resort's problems, such as traffic congestion and beach crowding, are exacerbated by the city's high-density building boom.

"Conditions are getting a little harder to cope with," said Ann Marciano, president of the Montego Bay Civic Association. "The future of the town is in grave danger due to the overburdening of the community."

The proposal was hotly contested by developers, builders and real estate agents, who argued that changing the city's zoning code could spell economic disaster. They noted that no economic impact study had been undertaken to determine what would happen to the city's tax base, land values and economic prosperity if development were limited further.

"We are against any change in the ordinances," said Ronald Goodman, past president of the Developers of Ocean City Association. "We think any change in density can bring an economic disaster on the community."