A free tour of buildings in the District with solar heating and cooling systems is being held from 11 a.m. to 4 p.m. today and tomorrow under the sponsorship of the Institute for Local Self-Reliance, the Department of Energy, Anacostia Energy Alliance and the D.C. Solar Coalition. Self-paced tours by car and public transportation will begin at the Early Day/80 location at Third Street and Independence Avenue SW, opposite the National Air and Space Museum. Homes, public buildings and a community solar greenhouse are included on the tour.

The 52nd annual Georgetown Garden Tour, which will include gardens of 12 homes, will be conducted next Saturday beginning at 10:30 a.m. Ticket information is available at 333-4953. The tour will benefit the Georgetown Children's House, a daycare center for low-income families.

Prison Fellowship Inc., a rehabilitation program for "born-again Christians" headed by Charles Colson, has purchased a small building at 10205 Colvin Run Rd., Great Falls, for $621,500 from Colvin Run Associates, the developer. Shannon & Luchs handed the sale of the two-story building, which will be the headquarters of the group.

A program dealing with downtown redevelopment will be held at 6 p.m. Wednesday in the Marvin Center ballroom of George Washington University. Sponsored by GWU and the Washington Board of Realtors, it will include a discussion of Metro Service, the civic-convention center, the money market and Pennsylvania Avenue redevelopment. Admission is $8 and reservations may be made by calling 628-4494.

Attorney Benny L. Kass will conduct a seminar on creative financing May 10 at the Wellington Hotel, 2505 Wisconsin Ave. NW. The cost is $40 per person. For information, call Real Estate Resources, Inc., 966-5703.

Condominium maintenance will be the topic of a workshop at 8:30 a.m. next Saturday at the National 4-H Center in Chevy Chase sponsored by the Community Associations Institute. Advance registration may be made by calling 569-2147. Seminar speakers will discuss pools, landscaping, mechanical systems, roofing and painting.

Roger L. Applegate has been named sales manager of the new Long & Foster Realtors' office in Burke Centre. Crestwood Village, an adult community at Frederick, Md., will mark its first anniversary May 14-17 with social activities at the newly completed clubhouse.

Realtor William H. Laughlin of McLean has been designated a certified resident broker by the National Association of Realtors E. F. Krebs, a Lanham Realtor, has been given the certified residential salesman designation by NAR.

Congressional Information Service Inc. has leased 40,364 square feet in the new Bethesda Office Center at 4500 East-West Hwy. and will move in this fall. Arthur Rubloff & Co. of Washington handled the negotiations, along with Julien J. Studley Inc.

Christopher Albrick has been named condominium marketing manager of Long & Foster Realtors and Mary Walker has been named marketing manager of the firm's new-home and condominium division.

A $19 million, wraparound refinancing loan for the eight-story office building at 2000 L St. NW was arranged recently by Frank S. Phillips Mortgage Corp. with New England Mutual Life Insurance Co. The block-long office building is owned by L. J. Development Associates, a limited partnership in the District.

Dear Run Crossing, a new community of 102 houses, has been opened by JayBee Builders Inc. on South Kings Highway near Telegraph Road, south of Alexandria. The site is adjacent to the 1,242-acre Huntley Meadows Park operated by the Fairfax County Park Authority. The houses, designed by architect Morton Noble, are priced from about $90,000.

Strathmore, a group of California-style contemporary town houses, has been opened by the Porten Corp. on a site along Strathmore Lane in Kensington, South of the White Flint Mall. Priced from $180,000, the brick and cedar houses have two-car garages. Sales are by Lewis & Silverman.

Allwin Building Corp. has a contract to purchase nine undeveloped acres at Rockville Pike and Grosvenor Lane, North Bethesda, where it plans to build expensive town houses, starting next spring. Allwin, headed by Bruce Winston and Allan Fried, currently is building the 438-unit Arbory condominium community in Laurel.

Copies of a new publication for builders, Design of Wood Frame Structure for Permanence, are available for $1.20 from the National Forest Products Association, 1619 Massachusetts Ave. NW, Washington 20036. The bulletin describes methods and practices that ensure long-term durability of wood-frame structures.