You wouldn’t call billionaire investor Wilbur Ross a bull on commercial real estate now.

He says a “huge crash” has begun in the sector.

“All of the components of real estate value are going in the wrong direction simultaneously,” Ross, CEO of WL Ross & Co, told Bloomberg.

“Occupancy rates are going down. Rent rates are going down, and the capitalization rate – the return that investors are demanding to buy a property – is going up.”

U.S. commercial property sales will hit the lowest level in almost 20 years, estimates research firm Real Capital Analytics Inc. Already, the Moody’s/REAL Commercial Property Price Indices have dropped 40 percent over the last two years.

Ross told Bloomberg he will exercise extreme caution before putting money into commercial real estate, especially office buildings. That’s because tenants are deserting office space in droves.

Office vacancies surged to a five-year high of almost 17 percent in the third quarter. “I think it’s going to take quite a while to work itself out,” Ross said.

Real estate icon Sam Zell takes issue with Ross’ pessimism.

“(As for) all the new savants on commercial real estate like Wilbur Ross, . . . I find their comments are inversely related to their knowledge of the industry,” Zell, chairman of Equity Residential said in a recent speech.

While Zell isn’t a raging bull, he says building vacancies won’t be an issue by mid-2011.