Every facility faces ice and condensation contamination, even when it’s not visible. It lives inside the roof, walls and insulation where it is not visible. Most facility personnel don’t even realize it’s a problem until it comes to the surface. Many owners and directors refuse to even believe it’s a problem.
All the interlocking components that make up your facility—different building materials, climate, internal temperatures—work to create holes in the vapor barrier. When your building envelope allows condensation, food gets contaminated. And, with the new Food Safety Modernization Act (FSMA) already in force, the penalties will only increase.
It doesn’t have to be this way.
Understanding air movement
Though it may be invisible, the air around us is made up of tiny molecules of oxygen and nitrogen that move based on their temperature. Warm molecules jump around, colliding with one another in an energized frenzy. Cold molecules are more relaxed, moving with less energy and colliding less often. This is the starting point in understanding how air flows from one area to another.
Those fast-moving particles don’t want to stay in one place. As air warms, the particles rise, and as it cools, they fall. Because nature hates a vacuum, whenever warm air does rise, cold air moves in to replace the air that just left. This cycle continues endlessly across the face of the earth and is impacted by geography, moisture, population density and even the rotation of the earth.
Understand vapor drive, ice buildup and condensation
All the forces that play into the movement of air on a large scale also occur on the small scale. In many ways, the beauty of natural systems lie in their predictability. Warm air will always rise, cool air will always fall, and one will always flow in to replace the other. But, if you’re tasked with the responsibility of trying to keep cold air cold, the inevitable invasion of warm air will be your worst enemy.
Imagine the freezer in your kitchen. When you open it to grab a bag of frozen vegetables, you’re always met with a rush of cold air. As the cold air leaves the freezer, it’s replaced by the warmer air inside your home. Once you close the freezer door, the air inside is now warmer than it was before and your compressor needs to turn back on to remove the warmer air from the sealed compartment and lower the temperature back below freezing.
Now, imagine you left the freezer door open just a crack throughout the night. Cold air would constantly be flowing out of the compartment, warm air would constantly be invading and your freezer’s compressor would be working overtime to keep up while ice starts to form. The same problem would happen with your refrigerator working overtime and condensing water on all your food. Now, multiply that single freezer in your kitchen by the size of one warehouse-sized cold storage facility and imagine warm air invading through every door, ceiling crack. Now, you can begin to understand the problem the cold storage industry faces with building air infiltration.
Assess vapor drive sources
The sources of vapor drive differ from facility to facility, but it often comes down to one simple factor—the quality of a building’s envelope. If a cold storage facility isn’t airtight, warm air will find its way in.
Every open door, HVAC duct, cooling pipe and ceiling and wall joint are open gates for warm air to enter. Warm, outside air seeps into the building through gaps in the roof structure and then moves freely between dry storage, cold storage and the freezer areas.
When warm air meets the air in the cooler, condensation forms. When warm air infiltrates the sub-zero air in the freezer, ice builds up. Meanwhile, compressors are fighting against the warm air in an attempt to keep the building at a constant, cool temperature. Many facility operators try solutions such as foam, tape, metal flashing and other items that might look good for a while, but are actually not airtight or a vapor barrier.
Take the consequences of vapor drive seriously
While the physical byproducts of vapor drive may be annoying and inconvenient to a cold storage operation, vapor drive can have negative and costly consequences to the bottom line. They can include:
· Structural damage. Ice expansion compromises building and roof integrity while moisture from condensation promotes rust, leading to costly maintenance and repair bills.
· Wear and tear. Warm air infiltration makes it harder to keep buildings at a steady temperature. These fluctuations cause compressors to work overtime and wear out faster.
· Added labor costs. Workarounds are expensive and distract from the business at hand. Constantly cleaning up and removing ice takes added manpower.
· Contamination. Melting ice and condensation compromises food safety and bring enormous added liability issues.
By any measure, vapor drive is a huge threat to an efficient and profitable cold storage operation and must be addressed.
These are challenges cold storage operators face every day, and unfortunately lack the necessary tools to properly identify and combat the problem. In many cases, an operator’s only recourse is to increase the compressor output to bring the building temperature down by sheer force and employ teams of workers to chip away and remove ice by hand. Throwing more compressor horsepower at the building actually makes the problem worse. These issues are so common in the industry, many operators may not recognize ice buildup and condensation as a fixable problem. Instead they engineer cosmetic solutions by adapting more expensive technologies and compressor rates, or just accept the growing icebergs, rusted buildings and lost profit as a cost of doing business. But, it is easy if you use the right understanding, tools and processes.
Vapor drive solutions exist. So, use them
In 2006, operators at a 420,000-square-foot cold storage facility noticed evidence of ice buildup inside their freezer space and condensation dripping from the ceiling in the cooler. These visual cues led to a detailed invasive forensic evaluation finding rust and standing water in the “B” deck troughs and contaminated insulation above the freezer. In addition, the sheetrock and insulation above the cooler were completely saturated and essentially useless. And, the insulation above the freezer was contaminated with ice, greatly limiting its R value.
Further examination revealed gaps in the roof-to-wall ties as the likely source of warm air infiltration as well as freezers sharing walls with outside temperature loading docks and very warm battery rooms.
Under these conditions, the facility experienced great difficulty maintaining a consistent cold temperature. What’s worse is that the ice and water threatened the structural integrity of the building, limited product storage and exposed staff and food to contamination and physical danger.
To address vapor drive and the resulting ice and condensation contamination, the facility owner decided to make improvements to the building envelop in a phased approach. In 2011, the company sealed two sides of a cooler in 100- and 200-lineal foot increments.
A year later, in 2012, it made improvements to shared walls between a cooler and a loading dock as well as a freezer and a loading dock in 100- and 300-lineal feet, respectively. In addition, the cold storage facility improved a 275-foot shared wall between the cooler and the freezer.
At this point, one cooler's vapor barrier was completely enclosed and the facility saw energy usage significantly drop, reducing compressor capacity. The improvements also eliminated a spike in the kilowatt demand for the high-temp suction pressure.
In conjunction with installing motion sensing, low energy use lighting, energy efficient doors, variable speed drive chillers and replacing inefficient equipment, this facility switched from an ineffective conventional vapor barrier to a sealed building envelope, completely eliminating vapor drive. All these improvements reduced the facility’s energy expenditure from a beginning annual amount of $969,855 in 2010 to $533,447 in 2014. Over a 5-year span, the facility is saving over $400,000 annually in energy consumption for a total of $2 million and counting.
While increased energy savings may be an enticing reason to finally address air infiltration in your building envelope, new government regulations make it a requirement.
What’s next—FSMA and vapor drive
In past years, temporary, cosmetic and more expensive investments in compressors may have been an adequate solution to ice buildup and condensation, but with the recent passage of FSMA, cold storage facilities now have the increased responsibility of preventing food contamination incidents rather than simply responding to them.
A critical component of FSMA’s new prevention measures lie in high-risk facilities identifying potential food contamination hazards and creating plans that clearly address and curb these threats to food safety.
Apart from general cleanliness, preventing frost and condensation are the biggest concerns for the cold storage industry in terms of FSMA compliance. Condensation is a major risk factor for food contamination, and was cited as one of the primary causes in the recent Blue Bell Ice Cream listeria outbreak. In addition, FSMA specifically addresses condensation dripping onto stored food as a hazard cold storage facilities must prevent.
Simply put, ice buildup and condensation are common problems in the cold storage industry, and are the natural result of the mixing of warm and cold air. In many cases, repairing a building’s envelope will stop the intrusion of warm air and eliminate condensation and ice altogether. With the passage of
FSMA and potential liability issues of a contamination incident, ice and condensation can no longer be tolerated within the cold food industry.