H.T. Lyons, Inc., a full service mechanical contractor specializing in design, energy savings engineering and construction services.

The Problem

Reducing tonnage, capital equipment and energy costs for commercial HVAC systems.


H.T. Lyons Reduces AC Tonnage 25% by Incorporating HVLS Fans into HVAC Systems

Commercial air conditioning systems are expensive. The larger the indoor space that needs to be cooled, the larger the system that’s required, both in terms of number and size of units plus ducting.

H.T. Lyons, a full service mechanical contractor in Allentown, PA (and a subsidiary of PPL

Corporation) is on the cutting edge of creating “green” HVAC systems that get buildings LEED certified or ENERGY STAR rated. Scott Sine, Director of Energy and Engineering Services, knew about energy efficient HVLS (high volume low speed) fans as he had installed a competitor’s fans at a previous job years ago in order to help increase ventilation effectiveness.

Sine heard about MacroAir’s energy efficient Six-Blade HVLS commercial ceiling fans from Allan Witzell, of DSI Solutions in Quakertown, PA.

HVLS fans: large diameter, slow moving

A relatively new technology developed by life-long inventor and MacroAir founder Walter Boyd in 1995, HVLS commercial ceiling fans differ from standard 36-inch high-speed ceiling fans in terms of size, volume of air moved, and energy efficiency.

The smallest MacroAir Six-Blade HVLS fan is 8-feet in diameter, with the largest fan having a 24-foot diameter. These large, slow-moving fans move a large column of air gently down and out along the floor.

Says Sine, “It’s well documented that HVLS fans work well with regard to heat destratification, that is, they push heat down, but what isn’t well documented is how well they work in cooling applications. Allan, and his partner John Kelly, were good to work with in applying the technology in a less common fashion.”

Sine incorporates HVLS fans into two warehouse projects

H.T. Lyons designed HVAC systems for a 125,000 rented warehouse for Liberty Property Trust and a 95,000 square foot warehouse for Olympus.

According to Sine, AC systems don’t stir the air in the building that well, especially in warehouses that contain closely spaced large storage racks. This means that HVAC engineers have to add to the system’s tonnage and/or duct distribution when selecting equipment. By incorporating MacroAir six-blade HVLS fans into the HVAC systems, Sine was able to space AC units further apart – a strategy that required fewer units.

By incorporating the fans, Sine was able to “decouple” fan distribution from the cooling units. The HVLS fans focus on even temperature distribution across each warehouse; the cooling units simply pump in the necessary air.

“I pointed the small AC fans toward the HVLS fan, which then efficiently mixes the cool air throughout the building,” says Sine. In winter, the HVLS fan sequence operates in reverse, pulling warm air down from the ceiling to the floor, which helps reduce heating costs.

How HVLS fans supplement HVAC systems

Tonnage refers to the cooling capacity of an air conditioning system. One ton of cooling is equal to 12,000 BTUs/hour. Engineers often think “a ton is a ton, so what does it matter if you add fans?” According to Sine, HVLS fans help in areas of:

  • Ventilation effectiveness
  • Thermal mass
  • Evaporative cooling
  • Lower energy consumption
  • Optimized compressor staging

Ventilation effectiveness and thermal mass

The thorough mixing of air helps with ventilation effectiveness, but engineers often don’t consider using the building’s thermal mass when calculating this effectiveness. Concrete cools due to natural temperature migration from the ground. Blowing air directly on the concrete in large quantities allows for an increase in the transmission of that natural cooling to the interior space.

Evaporative cooling

HVLS fans also work very well in conjunction with air conditioning systems as they help with the natural evaporative cooling across the skin (the same way a summer breeze on an 80° F day feels “cool”).

Lower energy consumption

Increased evaporative cooling by the amount of velocity generated by HVLS fans allow building managers to raise the AC set point by about four degrees for the same cooling effect.

For each increase in degree, the energy savings is estimated at a 3 – 5% reduction in energy consumption – making HVLS fans an integral component of LEED certified or ENERGY STAR buildings.

Optimized compressor staging

A decrease in fan motor output is also a cooling plus. Although HVLS fans move slowly compared to high-speed fans, the proof of their power and energy efficiency is in the numbers.

One 24-foot HVLS fan:

  • Replaces 25 36-inch high velocity fans
  • Covers 20,000 square feet of space
  • Achieves efficiencies of 300+CFM / Watt at full speed versus 18-20 CFM/Watt                       for one 36” high velocity fan

A final advantage of HVLS fans, says Sine, is compressor optimization. In constant speed compressors, the longer you can make a compressor run, the more optimally it runs. Since cooling is now “decoupled” from air distribution, only the cooling units necessary need be “on.” In other words, if a building is run at 50% in a standard HVAC design, all four AC units would have to operate, which kicks the compressors on and off half the time – decreasing efficiency.

“By incorporating HVLS fans into the system,” says Sine, “only two of the four AC units need to operate – and each operates at maximum efficiency.”

HVLS fans help Sine reduce tonnage, ducting and costs

In both projects, Sine was able to reduce tonnage by 25% – a significant reduction – by supplementing each system with 24-foot MacroAir Six-Blade HVLS fans.

“Where I needed five AC units, I only had to buy four,” says Sine, “which more than paid for the cost of the fans. In addition, the AC units I did purchase required less ducting, which also saved on capital costs.” By lowering tonnage, Sine’s clients will also save tens of thousands of dollars in future heating and cooling costs.

Both warehouses comply for ENERGY STAR performance if the respective owners ever want to list their facilities.

“The movement of HVLS fans is deceptive,” says Sine. Because MacroAir six-blade HVLS fans move so slowly and are so quiet, one of his clients didn’t believe they would cool down his space and turned them all off. “He had to turn them on again once the interior grew too warm,” laughs Sine.

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