The Pacific Life Insurance Co. has a commercial real estate portfolio of $8.3 billion, but of all the construction loans the insurance giant has on its books, only one has been issued to a developer building an office project with no tenants committed to it.

That project is in Rosslyn.

Developer Monday Properties announced March 11 that it and partner Goldman Sachs have landed a $200 million construction loan from the insurance giant, about two-thirds of the total cost of the 35-story office tower at 1812 N. Moore St. the developer is building in Rosslyn.

“Usually it is very out of the ordinary for us to finance construction of a building that is not pre-leased,” said Tony Premer, senior managing director for real estate investments at Pacific Life. Although Pacific Life invests more in Washington area commercial real estate than in any other market, he said that he could not think of another loan in the company’s portfolio that resembled it. “It’s a unique financing for us. I can’t really provide any comps for it,” he said.

Premer said there were a number of things that attracted the insurer — headquartered in Newport Beach, Calif. — to the 580,000-square-foot Rosslyn project. He said Monday Properties had a unique insight into the neighborhood, given its broad holdings there. He said the building, built to top environmental standards, would be of extremely high quality and benefit from Rosslyn’s many transportation options.

Anthony Westreich, chief executive of Monday Properties, called Pacific Life in a press release “one of the preeminent construction lenders in the nation. The collaboration reinforces the quality of this development.”

Both Premer and Monday Properties officials declined to share details of the loan, but Premer said the deal included a number of protections (he said they amounted to wearing a belt and suspenders) that he said gave Pacific Life confidence that it would be paid off when it comes due in December 2014. “There’s some credit enhancements that really give us confidence it will get paid off at maturity,” Premer said. (Credit enhancements typically can include providing collateral, reserve accounts or other assurances.)

That does not mean that Premer has great confidence in Washington’s leasing market. Cutbacks in government spending and government contracting have slimmed leasing volume locally. Premer said he actually expects the situation to worsen locally before it gets better. But he said there was enough interest in the building — which has reached its final height but has not been completed — that it would fill up.

He also said he thought Monday and Goldman could have completed the project without any financing at all. “I’m not sure they needed the money,” he said.