Fans Keep You Warm?

With winter’s arrival and heating costs ramping up, facilities managers at warehouses and distribution centers are once again looking for ways to reduce energy bills without freezing employees.

It is a costly conundrum. Heating accounts for nearly 50 percent of energy use in warehouses and almost 40 percent of energy use in all non-residential buildings, according to the Commercial Buildings Energy Consumption Survey. Thankfully, there are numerous ways to reduce heater use and costs. Among the most efficient is the installation of a simple, cost-effective technology: ceiling fans.

Large ceiling fans lower heating bills in large spaces by combating thermal stratification. Anyone who works in a tall building in a cold climate knows the effects of this phenomenon, even if they don’t recognize the term.

Thermal stratification is the product of a basic rule of physics: hot air rises. Air from a forced-air heating system is generally 5 to 10 percent lighter than the air already in a space. As the hotter air rises, it forms temperature layers, or strata. The hottest layer is on top, at the ceiling; the coldest is at floor level. Therein lies the problem.

Most thermostats are located 4 to 5 feet off the floor, so they register the temperature at that height. Because the hottest air always heads toward the ceiling and because doors of any warehouse or distribution center are always opening and closing, the thermostat is constantly sending the message to the heater that it needs more heat. Naturally, the more the heater runs, the higher the heating bills. The taller the ceiling, the bigger the bill.

Stratification not only strains the budgets of DCs and warehouses, it also contributes to occupants’ discomfort, as the majority of employees work at or near ground-floor level, where the colder air hangs. Fans help by essentially “recycling” wasted hot air that rises to the ceiling, pushing it back down to employees and mixing the air, creating a uniform and comfortable temperature in the space.

Facilities of all sizes – from department store stockrooms to large warehouses to airplane hangars – have reported savings of up to 30 percent through the use of overhead fans.