Everyone seems to be using less these days, an altruistic endeavor they call “reducing your carbon footprint.”  To that end, energy consumption has been placed squarely in the crosshairs.  But wait... I still need to stay cool in the summertime!  Is there any way I can keep cool AND reduce my carbon footprint?  Why yes… yes there is.  I implore you to read on…

A study by the University of Stellenbosch in South Africa investigated a number of cooling alternatives and their effect on a one-room building.  The results were decisive:  evaporative roof spray showed the largest reduction in cooling load (59%) and the largest overall reduction in net energy transferred (72%).  Researchers also found that by continuously cycling cool ambient air through the building at night, and then using an evaporative roof spray system during the day, cooling load and energy transfer reductions improved an additional 5% and 8%, respectively.  This application is known as flywheel cooling.     

FLYWHEEL COOLING SYSTEMS AT A GLANCE

Night flushing is simply the movement of cool night air through a building by means of a ventilation system.  Generally, this system consists of at least one wall-mounted supply fan in conjunction with one or more wall- or roof-mounted exhaust fans.  Cross ventilation is important, so fans should be placed in such a manner as to allow air flow from one side of the facility to another.  Effectiveness is primarily due to air flow rate, expressed as air changes per hour.  Studies vary widely on the optimum number of air changes per hour, ranging from 10 to 30. 

An evaporative roof spray system intermittently sprays a thin film of water on the roof surface, and then allows the water to evaporate.  When performed in regular cycles, this prevents the roof from getting hot and transferring that heat into the building.  The result is lower air temperatures, and a reduced cooling load on the facility HVAC system. 

PRACTICAL APPLICATION

Most industrial sites can benefit from the use of flywheel cooling.  The ideal schedule would call for the supply and exhaust fans to be turned on at the end of the workday (or for a 24 hour operation, around 8 – 9 pm).  The fans would then circulate air through the facility until around 7 or 8 am the following morning.  At that time, the area should be “buttoned up” to retain as much of the cool night air as possible.  Then, the evaporative roof cooling system would be activated, preventing the sun’s radiant heat from penetrating the building.  The end result would be lower interior temperatures, since nearly 50% of the generated heat load inside a given structure emanates from its roof. 

BENEFITS

For sites that use large HVAC systems, incorporating flywheel cooling into the daily operations plan translates into direct energy savings and reduced electrical consumption.  Night flushing and evaporative roof spray greatly diminish the building’s cooling load, decreasing HVAC cycle frequency and duration.  Large consumers of electricity will also see an additional benefit of lower peak demand charges and ratchets often imposed by power companies.  The University of Stellenbosch study agrees, stating these methods “…not only constituted a saving in the energy consumed by a conventional air conditioner but also decreased the required size of the air conditioner.”  

The university study highlights another important point regarding air conditioning capacity.  In many cases, cooling load reductions may be dramatic enough to pull unneeded A/C tonnage offline entirely, bringing down yearly HVAC maintenance costs.  Facilities located in more moderate parts of the globe could take things even further: “…in milder climate conditions the necessity of a conventional air conditioner may be averted.”

Regardless of climate, HVAC capacity, or industry, environmentally and safety conscious organizations would do well to explore the prospect of adding flywheel cooling to their facilities.  The rewards of lower energy bills, more productive employees, and a carbon footprint reduction await.

REFERENCES

Artmann, N., Manz, H. & Heiselberg, P., (2008).  Parameter study on performance of building cooling by night-time ventilation, Renewable Energy, Vol. 33, pp. 2589-2598

Dobson, R. & Vorster, J., (2011).  Sustainable cooling alternatives for buildings, Journal of Energy in South Africa, Vol. 22, No. 4, pp. 48-66

Finn, D., Connolly, D. & Kenny, P., (2007).  Sensitivity analysis of a maritime located night ventilated library building, Solar Energy, Vol. 81, pp. 697-710

Geros, V., Santamouris, M., Tsangrasoulis, A. & Guarracino, G., (1999).  Experimental evaluation of night ventilation phenomena, Energy and Buildings, pp. 141-154

World business council for sustainability, [Online].  Available: http://www.wikipedia.com/theinnovationchain. [2009, October 16].

When deciding between a high velocity or high volume (HVLS) fan, one must first assess the given area - for while both achieve the goal of people cooling, each has its own set of requirements that maximize their effectiveness.

HVLS fans work best in open areas, where air can be accelerated vertically toward the floor, then outward in all directions.  Assembly and inspection lines, loading docks, and staging areas are all great examples where an HVLS fan would provide a comfortable working environment.

By contrast, high velocity fans provide horizontal air movement in more confined spaces, such as aisle ways, pick modules, or any area where material may be stacked floor to ceiling.  For more information on the best fan application for your facility, contact a Patterson sales rep today!    

OK, 80’s rock ballad reference aside, selecting the proper motor type for your industrial environment is vitally important – ensuring years of high performance and reliability from your high velocity fan.  Each type is specifically designed to protect the motor’s mechanical and electrical parts to varying degrees.  Not sure which one to choose?  Take a look at the descriptions below:

Open Drip Proof (ODP) – Prevents liquid from dripping into the motor within a 15° angle from vertical, but still allows air to circulate through the windings.  Clean, dry locations are ideal for a motor with an ODP enclosure.
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Totally Enclosed Fan Cooled (TEFC) – Possibly the most common and versatile of all enclosure types.  A small fan attached to the shaft on the back of the motor creates airflow to aid in the cooling process.  Keep in mind that although these motors are “totally enclosed,” they are not air tight.

Totally Enclosed Air Over (TEAO) – This motor has no internal or external mechanism to facilitate cooling.  Therefore, it must be mounted in the path of the manufactured fan’s airflow.  Many belt driven fans employ this motor type.

Wash Down or Totally Enclosed Wash Down (TEWD) – These enclosures can withstand a high-pressure wash down, and are a necessity for wet or chemical environments.  Common uses include food processing, packing, and pharmaceuticals.  Be aware that they are not for use in hazardous locations.

Explosion Proof (EXPL) – Essential in many hazardous industries like chemical, oil and gas, and wood processing.  A motor given this designation does not mean that it can withstand an exterior explosion.  Rather, they prevent an internal spark (or explosion) from igniting a much larger blast outside the housing. 

Have questions?  Still unsure of your choice?  Give Patterson a call!  Our knowledgeable sales staff is ready to discuss your application and provide the best possible air movement solution! 

“Warm air rises and cold air sinks” – anyone who’s taken a middle school science class has probably heard this fact at one time or another.  For now, we’ll skip over the details as to why this happens, because really, who wants to relive those awkward middle school years?!   But all jocularity aside, it’s this concept (commonly referred to as thermal stratification, or simply stratification) that’s straining the budgets of organizations like yours each and every winter.  Why?

Regardless of how you might heat your facility, the sad truth is much of that heat is lost to the ceiling space.  Because of this, heaters are forced to run more often in order to maintain their thermostat set points.  The colder it gets, the more they run, and the more you spend.  The end result is an uneven temperature profile (or gradient), whereby warmer air becomes trapped at the ceiling and the cooler, denser air sinks to the floor.  Depending on ceiling height, the temperature difference, floor to ceiling, can be as much as 15-20°F!

So now that we’ve identified the problem, can anything be done, and if so, how?  Thankfully the answer is yes, and the solution is Patterson’s High-5 HVLS (High Volume Low Speed) fan.   Think of this fan like the ceiling fans in your home, but on a much, MUCH larger scale.

The idea, known as de-stratification, works like this: strategically place a number of High-5 fans throughout your facility, and turn them on at a slow speed in the FORWARD direction*.  The fan should move air, but not create a breeze you can feel (a bit of experimentation will help you find the “sweet spot” for your building).  This will facilitate a mixing of warm and cool air in a vertical, circular pattern.  Over time, a continuous mixing of air will promote a more uniform temperature profile from floor to ceiling.

So how does this lower energy bills?  The key is the redistribution of warm air from the ceiling.  More warmth at the floor level means thermostat set points are maintained for longer intervals.  Heating cycles shorten in both frequency and duration, adding dollars back to your bottom line.  Realized savings could be 25-30% or more**!

Have more questions?  Want to learn more about the concept of destratification?  Contact the air movement experts here at Patterson Fan – The Authority in Air Movement!  With more than 25 years of fan experience, we’ll deliver a tailored High-5 solution that meets both your needs and your budget!
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*Best results are achieved with the fan running slowly in the forward direction.  A common industry misconception is that these fans must be run in reverse for destratification.  While air mixing will occur in reverse, it is much less efficient.

**Actual savings depend on heating costs, size of facility, number of fans, and other factors.