America's building sector often gets criticized for being an inefficient drain on the country's electricity system. At the same time, the natural gas industry gets held up as an economic miracle for the grid. But does that perception match reality?

A new analysis suggests that those assessments may be a little skewed -- at least when it comes to yearly revenues in those sectors.

Advanced Energy Economy, a clean energy business advocacy group co-founded by billionaire activist Tom Steyer, has released a report valuing the global advanced energy sector using data from Navigant Research. The report found that the global advanced energy economy -- which includes efficient transport, biofuels, commercial and industrial efficiency, and clean electricity generation -- was valued at $1.1 trillion in 2013.

The U.S. made up 15 percent of the global total across that wide range of sectors, with a $169 billion market.

Looking deeper into the numbers, a counterintuitive trend emerges: building efficiency revenues actually outpaced revenues in the clean electricity sector in 2013.

The report breaks down building efficiency subsectors into the categories of environmental design, HVAC upgrades, lighting, water heating, district heating, demand response and building energy management software. Taken together, these subsectors represented $43.9 billion in U.S. revenues and $150 billion worldwide. 

The analysis focused on clean electricity factors in the solar, wind, geothermal, hydro, nuclear, natural gas turbine and fuel cell subsectors. Combined, those technologies brought in $31.3 billion in revenues within the U.S. and $384 billion worldwide, according to the report.

Globally, revenues in clean electricity generation were more than twice those in the building efficiency space. But in the U.S., the building efficiency sector brought in roughly one-third more revenue last year, according to the report. That's a significant gap, and it illustrates the steady (and sometimes hidden) investment underway in the built environment.

Wind and natural gas are often hailed as the dominant forces in the clean energy sector. In 2013, however, wind investments plummeted due to uncertainty about the federal production tax credit. Orders for natural gas turbines have also also declined over the last two years as older plants are utilized more efficiently and flattening electricity sales slow investment in new infrastructure. Meanwhile, investment in building efficiency is increasing steadily, rivaling the top generation technologies.

Even with a strong showing for wind and gas in 2012, the clean electricity sector only brought in about $6 billion more revenue than the building efficiency space.

These figures back up a couple of recent studies on the value of efficiency.

In April 2013, sustainable architecture expert Ed Mazria analyzed EIA data and concluded that theoretically, no new power plants need to be constructed to service America's 60 billion square feet of new buildings by 2030. That's because new construction is becoming so efficient that building energy consumption will see a steep decline even under a business-as-usual scenario, according to the EIA.

Also last year, ACEEE energy economist Skip Laitner compared economy-wide investments in efficiency to energy production for the year 2010, finding that America spent three and a half times the amount of money on efficiency upgrades that it spent on energy supply. 

"One immediate conclusion from this assessment is that the productivity of our economy may be more directly tied to greater levels of energy efficiency rather than a continued mining and drilling for new energy resources," wrote Laitner.

It would be premature to draw any definitive conclusions from the data in this latest AEE report. But the analysis does suggest once again that building efficiency is a much bigger force that people assume. And if investment keeps its current pace, it will likely continue to rival the more visible clean electricity sector.