Move Air to Save Energy

Circulator fan. by rlz
Circulator fan. by rlz

Who hasn’t enjoyed the cooling breeze across a sunny veranda? Or the chilling effect of the stiff winds breaking at the prow of a motorboat? Let this architect show you how moving air can move your energy bill lower.

Throughout the United States, we consume great amounts of energy to cool our interior environs. Even in colder months, most of our heavily populated office buildings, shops, factories and schools still have significant cooling demand, to offset the warming and excess heat generated by people, appliances, machines, industrial processes and lights. At other times, we pump heat continually into occupied spaces in winter, only to find that drafts and chill spots still occur. Heating and air conditioning systems can not only become great energy hogs, but can also produce drafty or ‘stratified’ spaces in which cold and hot zones are unevenly distributed, or where cooling or heating too often occur where people are not. The use of fans to move conditioned air to where it is needed may provide an additional low-energy solution.

At one time or another, we have all used a small fan — handheld at the ball park, cubicle-mounted at the office, patio-bound at the height of summer — to circulate air in our immediate vicinity for greater comfort. We have also all used the occasional spot-heater, whether we have warmed our hands or backside at the fireplace, or tucked our feet closer to a small space heater nestled under our desk. But, as architects create great and soaring spaces, for such facilities as cathedrals, airports, warehouses, gymnasiums, and auditoria, larger fans that move greater volumes of air can offer relief to occupants, often more cheaply than increased heating or air conditioning capacity.

In too many such spaces, enclosed air can become layered, stratified or adversely segregated. Thus, all the warm air in the school gym in February is resting atop the high-intensity lights spaced among the roof trusses, leaving spectators below huddled and chilled. Or, conversely, none of the mall’s air conditioning in August can be felt under the intense sunlight penetrating the skylit food court, leaving moms and children stifled and baking. One solution offered to designers and architects is the circulator fan, or high-volume low-speed fan (often referred to, of course, as an HVLS fan).

Circulator fans are quite unlike that small fan you used to place on your cubicle wall or shelf for personal cooling. To optimally move large quantities of air with low energy input, circulator fans typically employ up to 8 very long and very thin un-twisted blades with tip-end winglet airfoils, moving at a rather lazy spin (whereas your small fan probably had just 3 or 4 short, wide, tightly curled or twisted blades, moving quite fast). Due to their ideally long blade dimensions, the most energy-efficient circulator fans are typically in the range of 12 feet or more in diameter, and are therefore located throughout large spaces at intervals of 30 or 40 feet or more. Depending on the particular building or space, its use or function, and the particulars of its heating and cooling loads, circulator fans may offer overall annual energy savings ranging from 10% to 40% or more.

You find lots of other great ideas at rickzworld.

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