Robert Martin has also been unusually successful in being able to retain tenants, especially I.B.M., which leases a total of 335,000 square feet in its buildings.

"This is a value-added amenity that helps lease space and retain tenants," he said.

The study found this happens whether or not the apartment is regulated, because landlords in nonregulated units hold down increases to retain favored tenants.

Richard Stadtmauer, managing director of Kushner, said his company was convinced that offering advanced telecommunications services would distinguish its properties and help retain tenants.

And it redoubled efforts to retain existing tenants, and to get them to generate good word of mouth.

Those services help to retain tenants and a happy work force while giving a sense of distinction in a market where one suburban office building often looks much like the next one.

The focus is on retaining existing tenants and attracting new ones, he said, adding, "Cash flow is king and owners don't want holes in their buildings."

That does not mean we have to achieve that by retaining the current uses or current tenants on the piers.

He said landlords try to retain growing tenants by finding them other areas in their buildings that have more space.

Despite renovations, nearby Park Lane Mall struggled to compete with Meadowood Mall and had been failing to retain tenants for several years.