The nation's organized homebuilders will press this year for "emergency housing legislation" that would be triggered whenever housing starts fell below about 1.5 million units a year, the new president of the National Association of Home Builders said here today. Housing starts have fallen to between 1.3 million and 1.4 million as high interest rates have driven most buyers out of the market.

Herman J. Smith, the Fort Worth builder who moved into the NAHB's top elected post at the group's convention here, said that builders are seeking legislaton that would permit agencies such as the Department of Housing and Urban Development, the Federal Home Loan Bank Board and the Office of the Comptroller of the Currency greater "management of the monetary cycle," so that housing production does not drop.

Seven such cycles have affected housing since World War II, Smith said, and in each down cycle the impact on business has been harder. Each time, for instance, small suppliers are eliminated, he said, with the result that "larger, less competitive suppliers" are left to dominate the housing industry.

The builders would consider more than 2.3 million housing starts a year "inflationary," Smith said, and also would want any emergency action to be triggered at that level, which is considered the optimum number of units needed per year in the 1980s.

The NAHB, whose 44,000 builder members are said to construct more than 80 percent of the housing in the United States, also are calling for tax incentives to stimulate construction of privately financed rental apartments for moderate-income families. Currently, most multifamily units are built with government subsidies or as condominiums.