Limbach Energy Solutions is hiring employees.

That alone is probably worth a headline, but the Pittsburgh-based company's news this week is actually that it plans to take a business for retrofitting schools, hospitals and government buildings for energy efficiency developed it has honed in Ohio over the last several years to other markets. It will now begin to perform energy assessments and retrofits in Boston, Detroit, L.A., Pennslyvania, Florida and Washington. D.C.

It's the culmination of a few trends. Over the past two years, businesses, government agencies, venture capitalists and consumers have begun to recognize that energy efficient technologies – insulating windows, modern air conditioners, etc. – can have a larger, more immediate effect on energy consumption than solar panels or other forms of green energy.

"The payback generally is three to five to six years," said Charlie Bacon, Limbach's CEO. Many of the Ohio retrofits, he adds, are also cash flow neutral: The money spent on retrofit services can be covered by the decrease in operational expenses.

Federal and state incentives have also begun to pour in. The American Recovery and Reinvestment Act, for instance, provides $4.5 billion to retrofit federal buildings and another $6.3 billion to grants for improving the energy efficiency of state agencies. Despite the downturn in construction, school retrofits and constructions are expected to grow. (The program started in Ohio because the state passed a retrofit program there years ago. If schools could show that retrofits would be cost-effective, they would receive grants.

Third, it's become painfully obvious that the building stock in America could use an overhaul.

"We have thousands of buildings out there that are energy hogs, particularly those from the '50s, '60s and '70s," he said. "About a year ago, things began to change."

Like many others, Bacon points the finger at heating and air conditioning (HVAC) systems and how they are operated and maintained. Lights are the largest consumers of electricity in buildings, but HVAC consumes the most power. The Department of Energy has estimated that building operations consume 39 percent of the energy in the U.S. and HVAC consumes nearly 40 percent of that, bringing the total to around 15 percent to 16 percent.

Energy consumption really took a jump in the 1950s with the rise in air conditioning. (As a company, Limbach can speak from experience. It was founded in 1901 and has survived the depression, two world wars and, temporarily, as a subsidiary of Enron.)

Bacon recalled one building Limbach examined. The systems, originally, were supposed to turn off their air conditioner at 8:00 p.m. and turn it on again at 6:00 a.m. Unfortunately, someone (or more than one person) tinkered with the thermostat. As a result, the air conditioners were running 24 hours a day.

He also noted that steam coming out of a grate, a signature motif in detective movies, is really just a sign that steam traps in a building's HVAC system aren't functioning properly.

Still, it takes some companies a long time to recognize the problems. "They'll say, 'If it is still working and I am getting heat, don't mess with it,' " he said.

Switching from a steam heating system, which requires heating up steam to 340 degrees, to a hot water system, which operates at 180 degrees "is the No. 1 gain in HVAC," he added.