Many of today's buildings suffer from what we'll call the "leak-guzzle-hide" phenomenon:

They leak billions of dollars through poor moisture, temperature and air pressure control -- akin to driving around with a massive leak in your gas tank.

They guzzle energy to satiate inefficient and often over-sized lighting, heating and cooling equipment, even when building occupancy is low. This is like commuting solo every day to work in an RV purchased for that once-a-year camping trip.

And they hide energy performance information due to poor metering and byzantine building management systems. Think about this as driving with your car's dashboard blackened out.

In fact, in its 2010 Annual Energy Outlook, the U.S. Department of Energy forecasts that buildings will soon become the fastest-growing source of demand for increasingly expensive electricity. In many countries, buildings are already the leading global cause (pdf) of greenhouse gas emissions.

While building owners struggle to tackle this trend, they also face the added challenges of high vacancy rates and tenants demanding better building performance (pdf), healthier indoor air and reduced utility bills.

The increasing number of regulatory energy mandates means that many existing commercial buildings -- which typically have life spans of 50 to 70 years -- will be legally required to reveal energy data and meet new laws that forbid continued "leaking," "guzzling" and "hiding."

Without significant renovation, today's commercial buildings may be unable to compete for tenants, financing or insurance. And if bringing them up-to-code is cost-prohibitive, some may even be left to crumble. In other words, today's asset may become tomorrow's albatross.

In fact, when we consider the fact that existing buildings far outnumber new construction (for example, the U.S. commercial building stock is 70 billion square feet as compared to annual new construction of 2 billion square feet) and is retrofitted quite rarely (for example, fewer than one third of U.S. commercial buildings have undergone heating, cooling, lighting, windows or insulation upgrades), we might be looking at a whole flock of albatross!

Unfortunately there aren't enough building engineers -- or in our analogy, car mechanics -- on the planet to deal with the sheer amount of redesign and renovation that's required. And at this scale, traditional techniques such as energy audits prove prohibitively expensive.

For example, ICF International estimated that if every commercial building owner in the U.S. did an energy audit of their buildings, it would take 1,000 auditors more than 13 years, working 365 days per year, to deliver recommendations on upgrades for 5 million buildings. So where should a savvy building portfolio owner put his next dollar?

When Autodesk faced the same question, we did what tourists do: We got out our camera.

In only a few days -- with zero travel budget, a few pieces of our own software, a novice user named Aniruddha Deodhar was able to convert digital photos of our office buildings to a building energy model that analyzed building energy consumption (within a few percentage points of our utility bills), as well as the building's carbon neutral potential.

"I was surprised at how little data was required to get a good snapshot of the six buildings' energy profile," said Deodhar.

We call this process "rapid energy modeling" and it involves these basic steps:

1.    Capturing the existing building conditions. In this step, you collect basic information about your building: the street address, five to six photos of its exterior, reference measurements like height and window area, the square footage of interest (for partial tenants) and anomalies not visible from the outside, like a large atrium or basement. An elementary school student could do this part.

2.    Modeling a simplified 3D representation of the building. To assess the internal volumes of your building, you use software to draw a rough model of your building based on the digital photographs and the other data captured during step 1. A middle-school student could do this part.

3.    Analyzing the energy consumption of that model. Using software that draws from highly-detailed weather, electric utility and building equipment databases, you simulate your building's energy and carbon profile. The software will also report the buildings' onsite solar, wind and natural ventilation potential. A tech savvy college student could do this part.

So while it's hardly a panacea, we believe rapid energy modeling can be of enormous benefit to building owners and their providers, helping them evaluate numerous design alternatives with less time and cost. Rapid energy modeling provides a:

•    Screen for identifying high potential buildings for further investigation and investment, helping to target facilities that would benefit from on-site building audits and renewables assessments, activities that can be very time and resource-intensive.

•    Stepping stone between a cheap-but-basic building benchmark and a pricey energy audit by providing a quick, sophisticated way of modeling and comparing energy consumption between buildings, and pointing to opportunities for improvement.

•    Shortcut to estimating actual energy consumption, when utility data is unavailable or of low quality.

•    Sketch of your ROI for proposed retrofits using local energy prices.

•    Scaling technique for assessing an entire portfolio quickly, allowing for bundled investments.

So to patch the leak, slow the guzzling and reveal the true energy performance of your buildings, it may seem counterintuitive, but we recommend you get out your camera.

Emma Stewart is the senior program lead for sustainability and Rick Rundell is the senior director of AEC Simulation Products at Autodesk.

The photos of Autodesk buildings accompanying this article were among the snapshots taken by Aniruddha Deodhar for rapid energy modeling. Images courtesy of Autodesk.