First Colony Homes, a division of J&J Construction, Inc., Calverton, Va. is opening a solar-heated house today in the Lake Montclair subdivision near Dumfries, Va., off Rte. 95 at the Rte. 234 exit. Funded by a grant from the Department of Housing and Urban Dvelopment, the system was designed by the Westinghouse Electric Corp. It uses solar power in combination with a heat pump for both heating and cooling the house, which is highly contemporary in design and thus able to accommodate the solar panels unobtrusively.

Published property transfer records show that Treasury Secretary W. Michael Blumenthal has purchased a house at 2964 University Ter. NW for $295,000 - without having to apply for a mortgage loan. Blumenthal, who had been living in the Detroit area with his family, bought the dwelling from Frederick B. Dent, Secretary of Commerce in the Ford administration.

Has the housing market cooled? Not so according to Roger Drebeen, vice president for sales of Lewis & Silverman, realtors. He said: "We had 108 sales of new houses, town houses and condominium apartments last week. I can't remember a bigger week." He cited leaders as Willow Hills town houses (16) the the Landover area, the Skyline high-rise condo (9) and Stocktown Towne town houses at Gaithersburg (9).

What about that nationally published report, that HUD Secretary Patricia Harris is upset about something and plans to resign. "Absolutely untrue," said Veteran HUD public affairs officer Jerry Hurd. "And I should know because I observed the about-to-go signs before George Romney departed."

George Washington University wants to build an office building in the block bounded by 19th, 20th, F and G strets NW and lease it to the World Bank for 30 years. Alan Hodges, president of the National Capital Chapter of the American Institute of Planners, has written to the D.C. Zoning Commission opposing the request for rezoning there. He called for "sensitive development" of the tract to protect the "pleasant and increasingly rare environment created by low-scale buildings and to preserve historic landmarks" (of which there are three). "The square is strategic because of the transitional or buffer role it could paly because its lies between high density office buildings and the residential-university community," Hodges said.

Long & Foster Real Estate, Inc. relators, has set up a commercial leasing and management office in Tysons corner, with Marty Irving as director. His staff has prepared a printed marketing pitch on that TC area, which is described as "the center of industry and commerce in Northern Virginia." The conclusion is that market absorption of office space is now 400,000 square feet annually on average but that only 80,000 feet is available in 1977 and little firmly projected for 1978. "A quality office project will be able to command rental rates of $9.50 (a foot) and a quality project with a 1978 delivery date is as speculative as betting on Secretariat in a one-horse race," the staff said. But the chaps in The Post's sports department point out that Secretariat is relatively serene and at stud at Claiborne Farms in Kentucky and not likely to get into the starting gate again.

Come June 6 and National Permanent Federal Savings and Loan Association will move to its architecturally spectacular new digs at Pennsylvania Avenue and 18th Street NW. The present 20,000-square-foot headquarters at 14th and G NW is reportedly on the market at $100 a square foot.

If you're eager to save a landmark building that dates back to 1874, take a look (or you may remember it from driving through Emmitsburg, Md.) at the former Western Maryland Hotel on a 60-by-148-foot site in the heart of the city that is the home of Mt. St. Marys and St. Josephs colleges as well as the Shrine of St. Elizabeth Ann Seton. The brick hotel structure, which has been a rooming house for the last 40 years, has been inspected by the Maryland Historic Trust and may get a nod from the National Trust for Historic Preservation. Shriver Realty, which is willing to make a deal for $62,500, says that the old hotel is structurally sound and has many fireplaces, high ceilings and a wide center hall entrance. Solid brick interior hall walls tie the building together.