LOUISVILLE -- Energy giant ConocoPhillips got a thumbs up on preliminary designs for its 2.5 million-square-foot campus Thursday from Louisville's Planning Commission.

Overall, the commission was supportive of the plan but concerns included the amount of open space to be dedicated. Commissioners also wanted more details on transportation and road improvement plans.

"I'm very much in support," said Commissioner Susan Loo. "It's probably one of the best designs we could have had."

The Houston-based energy company hopes to begin construction of a global training center, research and development facilities and accessory developments in 11 months. The company plans to construct the campus in phases over the next 22 years, opening its first phase in 2013.

ConocoPhillips is planning 3,000 parking spaces over the next three years -- giving hints of its initial employee base -- and a 95-foot-tall research and development building for its campus at the former StorageTek site off U.S. 36.

The company has requested that the city grant vested rights so it could construct buildings in the range of 65- to 95-feet tall, the latter being more than three times the commercial limit. However, the city code does not allow such a request at the preliminary point of the planning process, and it would require an ordinance change.

Louisville requires 12 percent of developments to be dedicated as open space or parks, but ConocoPhillips' plan only includes 11.5 percent. The difference marks about 11/2 acres.

The Planning Commission added a condition that requires at least 12 percent in the final plan. But Commission Chairman Jeff Lipton said he wants ConocoPhillips to make a greater land dedication if a height waiver is approved by the City Council.

"Typically these things are a trade-off. We've given quite a bit," Lipton said.

ConocoPhillips officials agreed to work with the city on public land dedication issues.

The commission will discuss at its next meeting whether to recommend that the City Council change its municipal code to allow it to guarantee building heights earlier in the process.

The City Council is scheduled to discuss the preliminary plans on March 16.