Eliminating Vapor Drive

Energy represents the second greatest cost in industrial ammonia refrigeration, and a compromised vapor barrier is a significant contributor to energy losses.

Facilities often fight a losing battle against vapor drive and air infiltration and sealing the building envelope can produce significant savings. It comes as no surprise that efficiency is directly related to a facility’s ability to control vapor drive and air infiltration.

When the vapor barrier is compromised, warm, moist air flows over the tops of walls, seeps in from loading docks and creeps between the freezer, cooler and battery rooms. The resulting vapor drive and air infiltration can mean an increase in energy costs of nearly 20 percent.

A 500,000 square-foot distribution center with an average monthly electric bill of $100,000 could save nearly $250,000 per year by sealing the building envelope. Not only does the facility run more efficiently, but there are also savings in labor costs that are incurred when employees are hired to remove ice and condensation.

“The biggest benefit from a properly sealed building envelope is on the bottom line,” says Eric Finnerty, president of Vapor Armour, Inc. “I can’t stress enough the potential cost reduction in your operation. Imagine that you’re trying to cool a 100,000 square-foot freezer section and warm air is leaking in from the outside. It’s like running your air conditioner at home with the windows open.”

Additional costs are incurred with the energy needed for defrosting.

The build-up of ice and condensation is a universal issue with cold storage facilities. Moisture leads to the corrosion of pipes, which, if left unchecked, can cause a hazardous situation. It also creates a breeding ground for microbes that in the food industry results in risk of contamination and product recalls.

Despite the obvious benefits of maintaining a vapor-tight facility, the ammonia refrigeration industry has been slow to embrace new technology that can retrofit existing facilities to create tighter building envelopes and vapor barriers. For many years, certain levels of vapor drive and air infiltration were considered unavoidable, and the loss in energy efficiency was seen simply as the cost of doing business.

But that attitude is changing, and not solely because of technological advances. The Food Safety Modernization Act (FSMA) that took effect in September requires that facilities eliminate condensation and ice from coming into contact with food products.

“This is a huge issue that is about to affect the industry. Now you have a government agency getting ready to come in and inspect your facility for ice and condensation,” Finnerty says. “Not only is there the energy efficiency benefit from sealing the building envelope, but there is now the contamination issue. Sealing the building envelope and eliminating vapor drive is more important than ever.”

The return on investment for retrofitting an existing facility is typically five years, according to Finnerty. So how should facilities address the issue of vapor drive and air infiltration?

Finnerty says the first step is to conduct a forensic evaluation of a facility. The steady increase of energy consumption needed to maintain temperature is a sign of vapor drive, which is the movement of humid air from one location to another. But the source of the issue is often hidden. Once the source is identified, a plan can be set in motion to seal the building and eliminate the ice.

“A vapor barrier system in a controlled environment is the most important part of the building when it comes to reducing energy usage,” Finnerty says. “With advances in technology, we have materials available that eliminate vapor drive from happening.”

And advanced cold storage door technology is now able to combine the insulating and sealing qualities of hard-core doors with the fast action of high-speed doors.

Thick, flexible foam core panels are better able to withstand impact and have a sufficient R-value to make defrosting unnecessary.

On the mechanical side, faster opening rolling doors with more effective perimeter seals have been developed.

With any system, a facility should research the investment and long-term costs as well as conduct a thorough energy analysis.

Facilities that have ice or a contamination problem should search out the new technologies that specifically address building envelopes and vapor barrier issues. “I’ve seen this problem in facility after facility for 25 years. The energy savings with a properly sealed envelope is staggering. Now the federal government is becoming involved, which ups the ante.”