The federal government's program to help low-income families weatherize their homes is hampered by continued inefficiencies, the General Accounting Office has concluded.

The number of homes made more energy-efficient increased substantially in fiscal years 1979 and 1980, the period covered by the report, from previous years, but it is unlikely this high level of activity will be maintained beyond 1981, GAO said.

The congressional agency found three major problem areas for the weatherization program:

* Continued overstatement of the number of homes weatherized because of inaccurate data from local governments and the inclusion of homes weatherized under another program.

* Incomplete or inadequate weatherization.

* Low emphasis on rental housing, where more than half of the low-income population lives.

"Weatherization of rental units continued to receive a disproportionately low emphasis in state and local programs. . . . To be successful, the program must attempt to reach that sector," the report states.

Other problems included poor workmanship and loose financialmanagement and monitoring by the state and local agencies in charge of the program.

The increased level of homes serviced is not likely to be maintained because of higher costs, budget cuts and the fact that high spending levels in 1980 and 1981 were largely a result of funds carried over from previous years, the agency concluded.

The GAO also said the Department of Energy has been unable to accurately assess the energy savings attributable to the program because of questionable samplings and data from local governments.

The agency's report recommended that DOE:

* Revise procedures to insure accurate recordkeeping and reporting by the states and local agencies.

* Require inspections of weatherized homes by local agencies before the units are reported as completed.

* Improve methods for determining energy savings.

* Instruct operations offices to oversee the state weatherization programs for reporting accuracy.