HVLS fans deliver energy savings from the top down

Indoor air quality: Food redistributor overcomes high ceiling and high energy costs to better manage heat

05/20/2013


Figure 1: When the warehouse operation at Dot Foods in Mt. Sterling, Illinois, was redesigned, they paid careful attention to how air movement within their facility was managed. Courtesy: Rite-Hite Fans/AMEDot Foods, the nation’s largest food redistributor, offers nearly 105,000 products from over 600 food industry manufacturers. Originally called Associated Dairy Products, the company was founded in 1960 by Robert Tracy, who started by selling products out of the family station wagon.

Over the past 50 years the company has grown from a regional, dairy products-only provider into a national operation handling all types of foods, virtually inventing the “redistribution” business model in the process. Today, it buys from food manufacturing companies and delivers to distributors nationwide in less-than-truckload (LTL) quantities. This “redistribution” model gives independent foodservice distributors access to products with lower purchase minimum requirements and shorter lead times. Customers can buy a mix of products (including dry, refrigerated, and frozen) with a combined minimum of just 5,000 lbs.

Warehouse operations have always been a key to this innovative, customer-centric formula, as summarized in Dot’s “Trusted Values. Innovative Solutions. Shared Growth.” brand promise. Dot Foods views its warehouse space as an extension of its customers’ facilities, allowing them to sink less money into buildings and inventory and more into building sales. The company currently has 2.8 million sq ft of warehouse space in eight distribution centers around the country, serviced by a fleet of 1,320 trailers and 830 tractors. 

An innovative solution

This dedication to innovative, quality warehouse space was evidenced recently when Dot underwent a massive, 145,000-sq-ft warehouse expansion at its Mt. Sterling, Illinois, headquarters. While any expansion of that magnitude poses challenges, this one was uniquely complex from an energy consumption standpoint.

Not only did Mt. Sterling endure cold Midwestern winters, the facility had extremely high ceilings—47 to 64 ft tall, which meant pushing heated air to the employees’ levels would be an issue. To make matters worse, the new section was going to be even taller, with ceilings up to 67 ft high. Another significant consideration was the area’s energy supply; the community did not have natural gas, which is generally considered the most efficient energy source for heating. Dot Foods’ only obvious option was electric heat, a less efficient alternative.

“I certainly wasn’t interested in heating the ceiling, particularly with electric heat,” said Nader Khalil, Dot Foods’ corporate engineering manager. “We needed to look at all available options to keep our energy costs down.”

As he began analyzing ways to design the most efficient HVAC system possible, Khalil learned of an incentive being offered by the local utility, Ameren Energy Illinois. Through its ActOnEnergy program, Ameren was offering customers a five-cent per kilowatt hour reduction of electric costs for each kilowatt hour the customer saved. Considering that the existing Mt. Sterling warehouse was using more than 25 million kWh of electricity per year, it’s understandable why this got Khalil’s attention.

Determined to find an engineering approach that would qualify for this incentive, Khalil soon became intrigued with the potential of incorporating high-volume, low-speed (HVLS) fans to complement the facility’s new heating system. Though the existing warehouse had made some use of traditional high-speed fans, he felt that HVLS fans had much more potential to improve air movement and reduce energy use. 

Better use of heated air

HVLS fans help save energy and improve comfort during the colder months of the year because they make better use of heated air. During the heating season, there is often more than a 20° F floor-to-ceiling temperature difference at most manufacturing plants and warehouses as a result of warm, light air rising and cold, heavy air settling. Typically, the air temperature will be one-half to one degree warmer for every foot in height. As such, a heating system must work hard for extended periods to maintain the temperature near the floor or at the thermostat setpoint, wasting precious energy and dollars.

HVLS ceiling fans address this issue by gently moving warm air near the ceiling back down toward the floor where it is needed. When the air reaches the floor below the fan, it then moves horizontally a few feet above the floor and eventually rises to the ceiling, where it is cycled downward again.

This mixing effect, known as destratification, creates a much more uniform air temperature with perhaps a single degree difference from floor to ceiling. With the use of an HVLS fan, there is less of a burden on the heating system, saving energy and dollars.

Conventional high-speed ceiling fans have been used to help circulate air for many years. However, these smaller fans are less effective in moving the warm air from ceiling to floor. A typical high-speed ceiling fan spreads out the air quickly as it moves away from the fan. The result is that little, if any air, reaches the floor. Because HVLS fans can move air up to 22,000 sq ft, they can replace 10 to 20 smaller traditional fans. And with their smaller motor and lower operating speeds, they cost only pennies an hour to operate.

After analyzing the potential of incorporating HVLS fans into the project, Khalil developed projections of HVAC system energy consumption both with and without the fans. These projections showed that Dot Foods could save 184,000 kWh in the first winter season alone by incorporating the fans. Based on that, the decision to purchase HVLS fans for the expansion project became what Khalil called “beyond obvious”—and Ameren Illinois agreed.

Ameren Energy was equally impressed with the warehouse destratification project and other energy-efficiency initiatives that Dot Foods had undertaken. “We are pleased that Dot Foods has teamed with ActOnEnergy to achieve their energy-efficiency goals,” said ActOnEnergy Business Program Manager Cheryl A. Miller.

Clearly the partnership between ActOnEnergy and Dot Foods has been a “win/win” for all stakeholders—including the local environment. 

Dan Anderson is a product manager for Rite-Hite Fans. This article originally appeared in Target, the official magazine of the Association for Manufacturing Technology, a CFE Media partner.

See more about how to assess your facility upgrade potential and how to access utility incentives below.



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