Advisors seeking a source for optimism need only turn to a semiannual three-year consensus forecast for real estate and the overall economy.

The study, co-sponsored by the not-for-profit Urban Land Institute in Washington, D.C., and the accounting firm Ernst & Young in New York, projects robust commercial property transaction volume. They expect it to rise from $290 billion in 2012 to $360 billion in 2015.

The issuance of commercial mortgage-backed securities, a key source of financing for commercial real estate, should soar more than 100%—from $48 billion in 2012 to $100 billion in 2015.

“It looks like the economy is going to be in very good shape,” said Kevin J. Thorpe, chief economist and principal at Cassidy Turley, a commercial real estate services provider in Washington, D.C., during a Webinar announcing the study results. Despite the potential bubble in financing, he added, “it’s far more grounded in the fundamentals and in underwriting than I have seen.”

This time around, lenders are using mark-to-market underwriting, Thorpe said. Underwriting is based on current rents and vacancies—not what they’ll be in a couple of years. “This says to me the [commercial mortgage-backed securities growth] is sustainable.”

The strong forecast, released April 10, was based on 27 economic and real estate indicators, and featured the median forecasts of economists and analysts. Thirty-eight real estate organizations were polled between March 4 and March 25.

Single-family housing starts, according to the study, should nearly double to more than 1 million units by 2015. The national average home price, which rose 5.7% in 2012, according to the Federal Housing Finance Agency, was projected to rise 6% this year before slowing to a 5% increase in 2015.

These figures come amid better economic news. Steady economic growth is projected; gross domestic product is expected to rise by 2% in 2013 and by 3.1% in 2015. Unemployment, 7.8% in 2012, should drop to 7.5% this year and 6.5% by the end of 2015. Employment is forecast to rise by 2.1 million jobs in 2013 and by 2.6 million jobs in 2015.

But before belting out bars of “Happy Days Are Here Again,” you should know that conspicuously absent from this survey was Robert Shiller, the Yale professor and New York Times columnist. Shiller, co-founder of the S&P/Case-Shiller home price indexes, predicted the real estate and tech bubble collapses. He has been vocal in the national media, throwing cold water on rosy real estate forecasts.

He warns instead that real estate has become a speculative and volatile investment. Nobody knows whether the mortgage interest deduction, government-suppressed interest rates and Fannie Mae and Freddie Mac will go away. Government intervention, he says, has created an artificial market. So as an investment, real estate needs to be considered as part of a diversified portfolio.

David Lee, the manager of T. Rowe Price’s real estate and global real estate funds, also offers caution. He warns that possible changes in the tax laws could impact real estate. Plus, rising interest rates could cause a decline in real estate fund share prices.

Josh Thimons, the managing director and portfolio manager at Pimco in Newport Beach, Calif., doesn’t see the United States ever returning to the housing euphoria that led up to the crisis. “We’ll never see so much easy credit in the system again,” he reported in his April economic outlook. “The bottom line is, we don’t see this as a housing recovery that will be sustainable over the long term, or be able to lift the entire U.S. economy out of its low-growth dynamic.”

Hamilton “Tony” James, president of the Blackstone Group, a private equity firm and heavy real estate investor, says that the future depends largely on interest rates. “The debt markets are clearly ebullient,” he said in an earnings call, adding that high-yield bonds have been trading above their call prices. “I’m not sure I ever saw that before.”

A catalyst that could ruin the party, he suggested, would be a debt market recovery that’s too buoyant. Or there could be some kind of crisis—a flight to quality.

But right now, he said, he sees no inflationary danger. Commodity prices are coming down and wage rates are under control. Credit people, he said, have shortened their durations, are investing in more floating-rate debt and are sitting on a lot of cash.

The Webinar participants, meanwhile, also discussed equity real estate investment trusts, which drummed up amazing returns of 28% in 2009 and 2010 and 18.1% in 2012. But those returns will cool off. They’ll hit 12% this year and steadily drop to 8% in 2015.

Craig Thomas, the vice president of AvalonBay Communities Inc., a publicly traded apartment building REIT in Arlington, Va., has seen some inflation pressures in construction costs. The Consumer Price Index, according to the Urban Land Institute/Ernst & Young study, should rise to 2.9% by 2015 from its slated level of 2% this year.

“The spreads between Treasurys and the [capitalization] rate [the rate for income-producing property that measures income divided by purchase price] are unusually wide right now,” said Thomas during the Webinar announcing the Urban Land Institute results. The study noted that 10-year Treasury rates should steadily rise to 3.5% in 2015 from 1.8% last year. “As inflation rises and long-term Treasurys rise, those spreads tend to shrink. As inflation becomes more of a concern, it becomes more important to have income-producing real assets in your portfolio.” Of course, Thomas acknowledged, you also can grow old waiting for inflation to arrive.

Suzanne Mulvee, a director of research for Boston firm Property and Portfolio Research, which analyzes commercial real estate markets, said at the Webinar that several sectors are contributing a fair share to economic growth. She also cited the forthcoming impact of the echo boomers—those born between 1980 and 1995—as a reason the housing market is undersupplied. She saw several good years in the sector.

But she worried about the nation’s fiscal deficit, about the impact of the $85 billion sequestration on employment and, even more so, about the effect of the payroll tax reinstatement on spending. She was also concerned about the pressure that a failure to manage rising interest rates could put on banks. Real estate, Mulvee said, is only a partial inflation hedge. If capitalization rates fail to keep up with the rate of inflation, “you’ve got a real problem in value.”

Mulvee also noted the spotty nature of retail real estate, which, she said, is still going through a massive repositioning. Not only are stores closing down, but there has been a technological shift in the way consumers shop. While retail real estate generally has been flat for a couple of years, she said, there are some strongly positioned centers—generally in urban areas—that “blew it out of the water.”

Akerman Senterfitt, a Miami-based law firm, has seen a record-high level of optimism in real estate since 2008 in a poll of builders and developers, REITs, lenders and private investors. Sixty-percent of respondents to its poll, involving more than 150 senior executives, see multifamily development as the most active market sector. Fifty-five percent believe the sector will return to pre-recession levels by the end of 2013. Only one-fourth predict the retail, hospitality and industrial sectors will begin to peak by 2014.

Those findings contrast a bit with those of the ULI/Ernst & Young survey, whose expectations for the apartment sector have dropped. While rents should rise 3.8% this year, the consensus says, they should slow to 2.8% growth in 2015 as new supply emerges. Vacancy rates were expected to hold at the same 5% level they were at in 2012, but edge up to 5.2% in 2014. Also, rental growth rates were expected to slow to 3.8% in 2013, down from 4.1% in 2012. These rates should drop further to 2.8% in 2015 as more units go on the market.

T. Rowe Price’s Lee agrees that commercial real estate is poised for a takeoff. He cites a lack of construction in commercial real estate coupled with the steady demand.

“We have been living in an environment of historically low interest rates, which has resulted in a hunger for income on the part of investors,” Lee says. “Real estate stocks typically pay relatively high dividends, and many companies increased their dividend payouts in 2012.”

But the Akerman Senterfitt executive poll suggests that people shouldn’t necessarily expect investment by private equity in the U.S. housing market to continue to grow as robustly as it has. Only 37% of those in the poll believe private equity is one of five top sources to fund portions of commercial real estate debt or equity in 2013, a 7% drop from last year.

Although private equity companies have been aggressively buying up and refurbishing properties for rent, published reports have indicated they might be overpaying, which might be one reason behind the market price increases.

During the Webinar, Thomas, of AvalonBay Communities, questioned the ability of private equity to sustain this trend. It’s too much of an administrative nightmare to manage stand-alone properties in so many markets across the United States, he suggested.

“We’ve never taken seriously the notion that private equity wants to be long-term renters of dispersed rental property,” he said. “I’ve always looked at it as a quick-flip situation. You buy them up and then you find some way to exit.”