The Miller and Smith building firm has organized a sales contest among employees in an effort to sell a total of 478 houses for $30 million by the end of September. The firm was ranked 168th in housing production among builders nationwide last year when it built 412 houses for a sales volume of $24.6 million. So far this year, 216 house sales have gone to settlement. About 270 houses were sold in advance and 78 are under construction but unsold and expected to be available for occupancy before the end of September.

More than 200 mortgage loan officers and appraisers are in Denver this weekend to attend an energy conservation seminar sponsored by the U.S. League of Savings Associations and the Institute of Financial Education. The goal is to aid home buyers seeking energy-related home improvement loans.

Construction is under way near the Beltway and I-95 on the Springfield Center Industrial Park, a 750,000 square-foot warehouse and office complex of four buildings. The first is nearing completion. Real Estate Service Inc. is handling the leasing.

The National Corp. for Housing Partnerships, based here, is looking for a successor to Sidney Freidberg, who resigned recently as general counsel and senior vice president and joined the law firm of Arent, Fox, Kintner, Plotkin & Kahn. Chartered by Congress, the NCHP helps arrange the building of housing for low and moderate-income families through private investment.

The Arlington Distributive Education Service, in co-operation with the Northern Virginia Board of Realtors, is offering several courses in real estate subjects. For information, call 558-2581.