TAMPA - The office development famine is over. But the feast might be hard to digest.

Commercial developers plan to build nearly 5 million square feet of new office space in Hillsborough County over several years, most of it in the West Shore Business District. The building boom comes after several years of relative inactivity, when few new buildings debuted despite a healthy local economy and growing job market.

The office developers are hoping to capitalize on the pent-up demand for new office space in the Tampa Bay area - and, naturally, the higher rental rates that have been spurred by a surge in demand.

Looking over the myriad projects, two questions emerge: Are there too many projects, and are they being planned too late?

Five million square feet represents a lot of office space - about four-fifths of all the office space in downtown Tampa. If all the office space proposed right now were built, the buildings would compete for tenants at a time when the growth in the population is expected to slow, and when employers are expected to add fewer new workers than they have in the past.

There's no question that Hillsborough County needs new office space. Local tenants need room to expand, and the county needs vacant space to accommodate companies that might wish to relocate from other parts of the country, according to Larry Richey, senior managing director of commercial real estate services firm Cushman & Wakefield.

Richey said he wouldn't be concerned about the roster of planned office projects if the pace of job creation in the Tampa Bay area was expected to remain constant.

'The reality is, I'm not sure we can count on that level of job growth going forward,' he said. 'In office space, demand is tied to job creation.'

Richey is right to be concerned about employment growth. Per Gunnar Berglund, a senior economist at Moody's Economy.com in West Chester, Pa., predicts the work force in the Tampa Bay area will continue to grow, but at a much slower rate than a few years ago.

For example, Moody's Economy.com reports that the work force in the Tampa Bay area is expected to grow just 1.2 percent this year, 1.5 percent next year, and 1.7 percent in 2009. In comparison, the work force grew 4.5 percent just three years ago.

Moody's Economy.com says the Tampa Bay area is ranked 175th out of 389 metropolitan areas for job growth from 2006 to 2011.

Why the slowdown in employment growth? Berglund blames the downturn in the residential real estate market, and its effects on consumer spending and in the financial services industry. He said things likely won't improve until the end of 2008.

Developers said they're not seeing signs that they'll be hindered by a slowdown in employment growth.

Larry Wilson, southeast division president for Koll Development, said he's seeing 'a lot of interest' in his firm's Intellicenter of Tampa, a two-building, 350,000-square-foot complex at Tampa Telecom Park in Temple Terrace.

Koll, which is based in Dallas, has broken ground on the first building, which will have 200,000 square feet. It should be ready in August 2008.

Wilson, who is based in Charlotte, said population and job growth demographics remain attractive in the Tampa Bay area, and that new buildings usually continue to attract tenants even when market conditions are slow.

'I do not necessarily think that we are late,' he said.

Bob Abberger, managing partner for Florida at Trammell Crow Co., also didn't appear worried about the employment trend.

For one thing, he said, many proposed real estate developments do not materialize. For another, he believes his planned Prime Meridian Center, a 450,000-square-foot building in the Channel District of downtown Tampa, can compete against the competition by offering suburban-style amenities in an urban setting.

'It's positioned to be the best of class,' he said.

Prime Meridian Center should be complete by the end of 2009.

Richey, of Cushman & Wakefield, said it's very possible that Hillsborough County ends up dealing with much less than 5 million square feet of new office space.

Developers don't always build every project they announce. When a project involves multiple buildings, sometimes the developer will complete one building and wait until the market is ready before proceeding on a new one, he said.

If developers end up building too much office space, the market will eventually correct itself, Richey said.

'There's one thing that's always certain when it comes to commercial real estate, and it's that development is cyclical,' he said. 'We don't know when, but the pendulum will shift back the other way.'

Reporter Dave Simanoff can be reached at dsimanoff@tampatrib.com or (813) 259-7762.