ARLINGTON HOUSING Corp. has won two awards, totaling $1,500, for providing homes for low-income families at substantial savings. The money was awarded by the Enterprise Foundation in a national competition for innovative ways to reduce construction costs of low-income housing.

Knightsbridge Development Co. gave three buildings containing 49 units to AHC last year after the county board gave the company permission to build a 14-story, luxury condominium nearby, instead of the 10 or 12 stories the original zoning would have allowed. Knightsbridge bought the 40-year-old Key Boulevard apartments three years earlier for $1.1 million, intending to tear them down to make way for the condominiums. The buildings are near the Rosslyn Metrorail station.

The AHC, a nonprofit organization, was honored for getting the building free and for saving more than $400,000 in rehabilitation and processing costs. It got a $690,000 loan from the Travelers Insurance Cos. to pay for the rehabilitation, saving $176,000 in transaction fees that would have been needed for a tax-exempt-bond issue, according to AHC. The other savings came from reduced loan application costs and from avoiding property standards that would have accompanied federal or state grants.

Judges for the Enterprise Foundation said the AHC's work was a "stunning accomplishment on a large scale."

IN THE BUSINESS . . . Midtown New York has overtaken London as the most expensive office market in the world, according to Richard Ellis Inc., an international consulting firm. Ellis puts total occupation costs -- including sevrice fees, taxes and the like -- at $69 a square foot for a high-quality, centrally located office suite in mid-town Manhattan, compared with $66 in London. Tokyo was third at $57.50, San Francisco fourth at $45 and Los Angeles fifth at $36. Washington was not on the chart . . . Say good-bye to the National Association of Automobile Dealers building at 2000 K St. NW, which is scheduled to fall to Wrecking Corp. of America to make way for a 100,000-square-foot office building.