The owner of a two-building office complex in Darien has taken a step toward filling them by signing leases with two area businesses.

Normandy Real Estate Partners, owner of 320 and 330 Boston Post Road, known as Darien Green, has signed the law office of Gaetano Ferro for 4,522 square feet at the 320 building, and Arch Insurance Group Inc., for 11,935 square feet at the 330 space.

Gaetano Ferro moved into a location that had been vacant for more than three years, while Arch Insurance is occupying space that had been empty nearly four years.

"We changed our focus from a single-tenant strategy for the 330 building to a multi-tenant approach and commenced a major face lift," said Mike Cottle, vice president of Morristown, N.J.-based Normandy Real Estate, which has offices in Boston, New York City, Los Angeles and Washington, D.C. "It's part of Normandy's DNA to ensure careful property stewardship and that tenants have an open line of communication with us,"

With the arrival of Gaetano Ferro, 320 Boston Post Road is 88 percent occupied, and 330 Boston Post Road is 42 percent occupied with Arch Insurance, which comes from Stamford.

The improving economy has not had a dramatic impact on office occupancy in the county, which has a vacancy rate in some areas of more than 20 percent.

In Darien, the rate is 13.5 percent, according to the Stamford office of Cushman & Wakefield.

"We are seeing tenants place a premium on stability of ownership and capitalization. Price is not the only driver," said Cottle, whose firm is asking in the upper $20s per square foot at the two buildings. "It's equally, if not more important for a tenant to know its tenant improvements -- and for the broker its commission -- will be paid. Tenants are looking for creative solutions for timing needs, work requirements and ease of the overall transaction."

Capital improvements at the two buildings, constructed in the early 1980s, are important in attracting renters, said Tim Rorick, senior managing director of the Stamford office of Colliers International, which represents the properties.

Represented by Paul Jacobs and Colin Reilly of CB Richard Ellis, Arch had been located in Stamford at 300 Stamford Place for a decade, and its lease had expired, said spokesman William Casey.

"Our lease was up, and we were looking for better space. The move to Darien posed no significant travel problems for our staff," said Casey, adding that the employees were included in discussions about the new location.

Ferro moved to the building after the retirement of Morton Marvin, a principal in Marvin, Ferro & Barndollar in New Canaan, resulted in the breakup of the law firm. Joining him in the move were attorneys Linsey Capecelatro and Janet Battey.

Ferro looked at locations in Wilton, New Canaan and Westport, said Shalini Madara, owner of Silver Pine Real Estate in Wilton, who assisted him in the search.

"This afforded him the ability to have the space he desired, as well as the aesthetic and proximity to I-95 and the Post Road," she said.