The Grubb & Ellis Co.'s quarterly analysis indicates that 965,564 sf of the 1.3 million sf that's under way is rising in the Katy Freeway/Energy Corridor, Sugar Land and Westchase submarkets. The Energy Corridor is leading the way with more than 500,000 sf being added to its 15.7-million-sf inventory.

According to Ariel Guerrero, the brokerage house's client services manager in Houston, the flurry of construction is attributed to huge growth and falling vacancies in the Energy Corridor. During the first quarter, the vacancy in that submarket was less than 5%.

"There's been a lot of growth overall in the west part of town during the past two years," Guerrero tells GlobeSt.com. "The Energy Corridor submarket last year had close to 700,000 sf overall in absorption. That's the reason why there's construction and anticipation. The developers feel the growth will continue on and they wanted to take advantage of it."