Despite controversial efforts by the Board of Supervisors to slow growth, Loudoun County's population and numbers of homes and jobs will more than double by 2025, according to new county projections.

Those estimates assume that recently passed development restrictions will withstand legal and political challenges and remain in effect. Under the former rules, there would have been an additional 85,200 people, 29,900 homes and 8,400 jobs by 2025.

The new numbers emerged from a broad-based effort to forecast how many schools, parks and other county services will be needed in Loudoun in coming years and where they should be located.

The statistics add a new level of specificity to what county officials say they already knew: Loudoun, with its good schools, safe streets and proximity to the nation's capital, will remain a choice destination for people moving to the Washington area.

Under current policies, most home building in coming decades will occur in the Ashburn, Dulles and Leesburg areas, while such older areas as Sterling and Potomac, and more rural communities in western Loudoun, will account for a much smaller percentage of growth.

The Ashburn planning area, which the county defines as the swath of Loudoun from Leesburg to Dulles International Airport, will account for more than one-fourth of the county's growth in each of the next 20 years.

County demographers estimate that Loudoun's more restrictive development policies will prevent the construction of 80,000 homes that otherwise would have been built at "buildout," the county's term for the point some time in the future when Loudoun would be considered full under current policies.

However, even supervisors who have pushed for the county's new Comprehensive Plan and stricter development rules contend that forecasting decades in an area -- and political environment -- as volatile as Loudoun's, is risky.

"Will that 80,000 decrease be a reality? I have no clue," said Supervisor Charles A. Harris (D-Broad Run). "Zoning is temporary. Ten years from now, the only thing I can guarantee is that the plan, the economy and the assumptions [underlying the projections] will be changed."

The projections were compiled as part of a wide-reaching look at the county by the Fiscal Impact Analysis Technical Review Committee, which consists of county and school officials, developers, an environmental activist and citizen representatives.

Another major finding was that Loudoun households are producing more children, which has implications for school construction plans. Officials said newer subdivisions tended to have more children than older communities do, in part because younger families usually move into the newer neighborhoods.

The county also projected that commercial construction, an important fiscal indicator, will average about 3 million square feet a year in coming decades, down from a high of 7.5 million square feet in 2000.

There were 196,314 people, 99,013 jobs and 73,006 homes in Loudoun last year. By 2025, there will be 423,040 people, 224,447 jobs and 158,782 homes, according to the county figures.