Benefits include uniform temperatures and reduced stratification.
As long as people have been erecting large buildings, the issues of how to heat and cool them to keep occupants comfortable have made builders scratch their heads. We’ve come a long way from open flame and open windows, but HVAC in large facilities remains a challenge in many cases.
Gentle, nondisruptive air movement augments both heating and air conditioning in large spaces. The simplest and most energy efficient way to add air movement on a massive scale is a familiar concept—a ceiling fan. Large diameter, low speed overhead fans aren’t only for summer cooling in nonconditioned spaces—they also enhance the effectiveness of HVAC systems, thoroughly mixing air throughout a space to create consistent temperatures from ceiling to floor and wall to wall.
In the summer, fans provide an additional boost to air conditioning systems. Because the perceived cooling effect of air movement can make a person feel up to 10F cooler, managers of conditioned buildings can raise their air conditioning setpoint and utilize energy-efficient fans to make up the difference. Customers and employees will feel the same level of comfort, which the building can maintain with far less energy.
“In large spaces, HVAC systems are generally not capable of effectively distributing air to all occupants,” explained Christian Taber, senior applications engineer and LEED accredited professional for Big Ass Fans. “Large circulator fans mix the air in the space ensuring good air distribution, creating uniform temperatures that increase occupant comfort and minimize stratification.” Large fans can be added to many existing structures, where they often are used to help qualify the building for energy-saving incentive programs. In new construction, specifying large fans when the HVAC system is designed can also help facilities eliminate a significant amount of ductwork, saving on initial building costs before the fans are ever turned on.
In the winter, stratification occurs because hot air is approximately 5-7% lighter than cool air in a space and tends to rise to the ceiling. In the winter, large diameter fans can be used to destratify heat by moving large volumes of warm air off the ceiling without creating a draft. The steady mixing of air creates a uniform temperature throughout the space, which can help the heater to maintain the same thermostat setpoint with less effort, resulting in a serious reduction of operating costs.
Unlike small ceiling fans that struggle to send air to the floor and only create insignificant pockets of air movement, large diameter, low speed fans gently mix air to stabilize air movement without creating a draft in winter, using patented airfoils and winglets to allow the fan to operate in the forward direction without causing a draft. Assessing a project Masood Kheradmand, president of Green Mechanical Construction Inc., of Lexington Ky., has installed large diameter, low speed fans from Big Ass Fans® in a variety of projects. Kheradmand uses fans to augment comfort in locations where numerous people are working, or in situations where additional ductwork will be cost-prohibitive or unattractive.
“Fans supplement the HVAC. As an example, I recently had a project with a requirement for consistency in the building,” Kheradmand said. “I didn’t want to spend a bunch of money to run ductwork, so I used the Big Ass Fans instead to keep the temperature steady.”
Case Study: Bell's Brewery
Bell’s Brewery in Kalamazoo, Mich., followed the advice of engineers and installed several large diameter fans in the new addition to their production facility. A green company at heart, the installation of the fans was twofold: provide energy-efficient comfort and look good while doing it.
The design concept revolves around simplicity. The building itself is a glulam-beam construction with the tallest point reaching 55 feet high. Five 8-ft. diameter Isis® fans from the Big Ass Fan Company are installed in the main brew gallery where the tanks are located.
“The architects really wanted us to keep our design simple and clean and not have a bunch of ductwork running all over the place,” said Bud Snyder, mechanical engineer with Byce and Associates. “We ran a main trunk duct through the middle of the space and then the Big Ass Fans are installed on the sides, moving the air around within the entire brew house.”
Depending on their running speed, these large diameter, low speed fans can work in two ways; to aid with cooling in the summer and destratify warm air in the winter, solving major issues of employee comfort, product integrity and energy costs. The facility has about 60,000 sq. ft of geothermal fields [in ground] acting as a heat-sink or thermal storage to increase efficiency of HVAC system, along with operable motor-driven windows. This combination allows them to manage heat through a combination of natural air flow, circulating air inside the space with Big Ass Fans, and heating and cooling performed through the geothermal field, explained John Mallett, Bell’s Brewery production manager.
“Being able to control that space better we’ll be able to have guests come and not sweat profusely. For that very important tour function, the fans are absolutely key,” Mallet said.