Walt SwietlikMaintaining an energy-efficient operation is becoming increasingly important in today’s competitive global market. Two of the best ways to do it – while simultaneously saving a few bucks – is with the right combination of loading dock seals and high-volume, low-speed (HVLS) fans.
Loading docks are critical conduits for receiving and distributing products, but they also present multiple energy challenges. Facility managers of manufacturing plants can address many of these hurdles using a system product at the loading dock that can end up saving companies thousands of dollars a year in wasted heating/cooling costs.
Loading Dock Energy Losses
Openings at the loading dock can allow conditioned air to leave and foreign contaminants like dust, water and even rodents to enter. From an energy standpoint, these losses translate into hundreds of dollars of conditioned air flying out the door.
Even when trailers are at the loading dock, 1- to 2-inch gaps often exist between a swing-open trailer and the edges of the dock opening. While an inch might seem insignificant, it equates to a 2.5-square-foot hole at just one dock opening; something that would be completely unacceptable if it were so obvious. These gaps can represent anywhere from $600 to $1,200 worth of lost energy every year. Multiply this over multiple dock doors and the financial loss is significantly more profound.
But the sides of the dock opening aren’t the only gaps in the building’s perimeter. Many facility managers forget about the “fourth side” of the dock – the bottom end, where the leveler, trailer, and dock seal or shelter all meet. Depending on the size of the opening, that gap can result in another $200 to $900 lost annually.
Look for Daylight
In nearly every case, the first rule of thumb is to look for light along the dock door perimeter. Anywhere there’s light coming through, there’s energy leaving the facility and an opportunity for contaminants to enter. These light leaks often appear on the sides and tops of trailers, but they can be present at any point around the perimeter.
Sealing the Perimeter with a System of Products
The key to getting an environmentally secure, energy-efficient dock is to get a consistent, gap-free seal along trailer sides, tops and corners, as well as at the bottom of dock door openings. An effective system of sealing products starts with a dock shelter that is specifically designed to overcome the most difficult sealing challenges.
Starting from the top, dock shelter head curtains help seal gaps by creating a seal at the top of the trailer. This is a common challenge made worse at facilities serviced by trailers of varying sizes, where head curtains must be frequently adjusted to reach lower trailers. Head curtains that utilize weight and gravity to create a solid connection with the trailer top are the best option in combatting this challenge. Weighted head curtains maintain a tight, consistent seal across the full width of the trailer, even as it bounces during loading and unloading. This type of header automatically adjusts to a wide range of trailer heights without requiring pull ropes or other forms of manual adjustment.
Trailer top corners, where the side curtains and head curtain come together, is a notoriously difficult area to seal and requires specially designed equipment to ensure an effective seal. Some products exist with corner pockets that help solve this problem.
On the sides of the trailer, keep the 2.5 cumulative square feet of opening created by exposed hinge gaps covered completely by hooks on the shelter side curtains.
Completing the Seal
While it is critical to effectively seals gaps at the top and along the sides of the dock opening, don’t forget the bottom. Gaps typically exist below and around the leveler and dock bumpers which present another challenge for energy costs and industrial hygiene.
Installing a seal under the leveler can offer a barrier against the elements on the facility’s exterior. Inside, lip corner seals, filler pads and other components keep the inside of the dock protected.
Sealing under and around the leveler will help keep dirt, debris and refuse out of leveler pit and close gaps that allow dirt, dust and insects into the building. Sealing these gaps will also help reduce heat transfer through the steel leveler deck and – as on the other three sides of the dock opening – will help prevent heated or cooled air from escaping the building and save thousands of dollars annually.
How HVLS Fans Improve Energy Efficiency
Effectively regulating indoor environments is an obstacle for many manufacturing facilities. Seasonal fluctuations in weather are an obvious challenge to indoor air quality and temperature, as are the expansive, wide-open layouts typical of these facilities.
While improvements to (or the additions of) HVAC and building management systems (BMS) can partially address these problems, savvy facilities managers have another weapon in their arsenal: networked systems of HVLS fans.
HVLS fans are an economical solution providing coverage of up to 22,000 square feet of floor space with a gentle 2 to 3 mph breeze. In fact, it takes nearly two dozen floor fans to equal the same output as a single HVLS fan. In addition, floor fans require more energy, make more noise and create potential trip hazards due to electrical cords.
By mixing heat-stratified layers of air, HVLS fans reduce energy consumption, boost HVAC system efficiency, combat air quality-related problems and promote cost efficiency throughout the building. What’s more, the comfort and cost-efficiency benefits of HVLS fans can be seen across all seasons.
Savings No Matter the Season
The benefits of HVLS fans are easily noticed in warm weather, where the gentle breeze provides an evaporative cooling sensation, reducing the effective temperature by 7 to 11 degrees Fahrenheit in facilities without air conditioning.
In air-conditioned facilities, HVLS fans can allow a higher thermostat setting (up to 5 degrees F) with no change in comfort. With electricity reductions estimated at 4 percent for each additional set point degree, HVLS fans can result in annual savings of 20 percent for many facilities.
In the winter months, HVAC systems often need artificially high set-points to maintain the desired temperature at floor level because a 20-degree F difference exists in comparison to the ceiling. HVLS ceiling fans mitigate this rising heat effect by gently moving the warm air near the ceiling back down toward the floor. When the air reaches the floor below the fan, it moves horizontally a few feet above the floor, eventually rising to the ceiling where it is then cycled downward again. This process, called destratification, creates a uniform air temperature with perhaps a single degree difference from floor to ceiling. Thus, facilities equipped with HVLS fans reduce the burden on their heating system and thermostat – reducing electricity consumption and saving money.
Save Energy and Increase Profits
Any facility manager considering a retrofit will likely be asked the expected return on investment. The right system of dock products can deliver one with a seamless connection from the back end of the semitrailer to the inside of the loading dock. Inside the facility, HVLS fans typically break even on the initial investment between 6 months and 2 years by reducing heating bills 20 to 30 percent. Get a complete seal at the loading and keep valuable conditioned air inside and circulating for a maximum energy value.
Walt Swietlik is the director of customer relations and sales support at Rite-Hite.
