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Federal law turns up heat on use of solar systems

  • Published
  • By Gil Dominguez
  • Air Force Center for Engineering and the Environment
By 2015, solar thermal energy will provide at least 30 percent of the hot water in new and heavily renovated federal buildings. 

For the Air Force, it will be the job of officials at the Brooks Air Force Center for Engineering and the Environment, as managers of the service's military construction, or MILCON, program, to ensure that its facilities comply with the provisions of the Energy Independence and Security Act of 2007.
 
EISA07, as the act is known, is an omnibus energy policy law designed to increase energy efficiency and the availability of renewable energy and reduce dependence on foreign oil. 

For most Air Force facilities that means installing solar collectors to make use of the free energy that shines down from the sun. Energy experts estimate that the sun radiates about 1,000 watts of energy per square meter, or about 10.76 square feet, of the earth's surface on most bright, sunny days. 

The collectors work by harnessing the heat produced by the sun and using it to heat water either directly or with a glycol solution that runs through a series of tubes. Solar thermal systems can be either passive or active. The latter feature a pump and technology that ranges from flat plate collectors to evacuated tubes. 

Chris Kruzel of AFCEE's Built Infrastructure Branch, said that solar collectors are a proven thermal-energy technology that can reduce the demand on a building's water-heating system. 

Mr. Kruzel, a mechanical engineer, provides technical support to the Air Force on MILCON and sustainability issues. 

"Solar collectors can replace 30 percent of the hot water demand but boilers still have to be working," he said. "(The collectors) are not meant to replace the entire system." 

In fact, solar panels may not be appropriate in some areas of the country where the weather doesn't lend itself the use of thermal energy. 

Also taken into account is the fact that sunlight doesn't hit all areas of the earth with the same intensity and so a large surface area may be required to collect enough energy to be useful. 

But in places like Hawaii, where utility rates are very high, thermal energy is a perfect fit and the majority of the homes there have solar collectors to heat their water, Mr. Kruzel said. 

In any case, before the equipment is installed, AFCEE engineers first determine if using solar collectors on a building is cost-effective. 

"All our projects should have a life-cycle cost analysis," he said.
 
All requests for proposal, or RFPs, that go out to the business sector require contractors to analyze the cost-effectiveness of solar collectors and make use of the technology if it is. 

An RFP is a document that tells vendors and other commercial firms the services or commodities that an agency requires. 

"The driving force is return on investment," Mr. Kruzel said. 

Although sunshine is free, solar collectors are not. And while the technology is not cheap, in the long run it will pay for itself in cost savings, he added. 

"The MILCON program is successfully incorporating all of our federal sustainable requirements, only one of which is solar thermal hot water," Mr. Kruzel said. 

AFCEE officials keep the overall sustainability "scorecard," making sure that, as required by Air Force policy, 100 percent of all of the service's military construction projects achieve a silver rating under the Leadership in Energy and Environmental Design, or LEED, program. 

That means buildings are healthier, cleaner and more energy-efficient than the ones constructed in the past. 

"We need to produce high-performing, sustainable facilities," said Dennis Firman, AFCEE director. "By the year 2020 we want to cut by 20 percent what it costs the Air Force to run its installations, and the use of thermal energy is one of the efforts that will help us reach that goal." 

Equally important, he added, is conserving finite resources and lowering demands on local power and electrical sources. 

"Reducing costs is critical to mission success, and increasing the sustainability of our facilities has a positive impact on the communities that surround our installations," said Mr. Firman.