What
is Evaporative Cooling?
How an Evaporative Cooler Works
An evaporative cooler produces effective cooling by combining a
natural process -- water evaporation
-- with a simple, reliable air-moving system. Fresh outside air
is filtered through the saturated evaporative media, cooled by evaporation,
and circulated by a blower wheel.
Cooling Temperatures
An evaporative cooler will nearly always deliver air
cooler than 80 degrees F. The chart below shows that an evaporative
cooler will deliver 78 degree air under a wide variety of typical
summertime climatic conditions.
In addition, the constant air movement created by an evaporative
cooler lowers the temperature perceived by room occupants -- called
the "effective temperature" -- by an additional 4 to 6 degrees below
the "evaporatively cooled temperatures" shown in the chart.
Finally, an
evaporative cooler works best in the hottest
time of the day. This is because relative humidity drops
quickly as temperature increases. For example, a morning relative
humidity of 60 percent at 75 degrees will drop to only 31 percent
when the afternoon temperature reaches 95 degrees.
| City/State
|
Outside
Temperature |
Humidity |
Evaporatively
Cooled Air Temperature |
| Buffalo,
New York Los Angeles, CA Phoenix, AZ |
88
94
106 |
54
38
16 |
78
78
78
|
Independent
research confirms these results.
A study of evaporative cooling by the prestigious Gordian Associates
research organization concludes:
"In large areas of the United States, evaporative air cooling can
provide essentially equivalent comfort conditions to a residential
building but at about one-third of the energy consumption of mechanical
air conditioning or a heat pump. "
Energy Savings
An evaporative cooler consumes only one-fourth of the electrical
energy required to operate a refrigerated air conditioning unit.
The Gordian Report on evaporative cooling notes:
"Evaporative coolers consume considerably less primary or resource
energy than mechanical air conditioners or heat pumps. Evaporative
coolers presently installed in the Western United States are estimated
to save approximately 6 million barrels fuel oil equivalent per
year in comparison to alternative cooling systems."
Gordian Associates estimate that evaporative coolers could save
up to 18 million barrels of fuel oil per year. With savings like
that, installing an evaporative cooler can be an important contribution
to energy conservation.
Energy Cost Savings
According to published figures, a 3 1/2 ton refrigeration unit consumes
some 8,698 kilowatt hours (KWH) of electricity during a six-month
cooling season. An evaporative cooler would require just 1,800 KWH
to cool the same home. This translates into a potential energy savings
of up to 6,898 KWH each cooling season! Dollar savings can be huge.
| KWH
Cost |
Home
A/C |
Home
Evap Cooler |
Savings |
---
4.5
8.0
10.0 |
8,698
$391.4
$695.84
$869.80 |
1,800
$ 81.00
$144.00
$180.00 |
6,898
$310.41
$551.84
$689.80 |
Health
Benefits
With
evaporative cooling, a complete air change occurs every one-to-three
minutes. This offers a great health advantage over traditional refrigerated
air conditioning, which employs a complicated "closed" system that
recirculates the same stale dry air over and over.
Constant cool air movement pushes heat out -- along with
stale air, smoke, odors and pollution.
The high volume of fresh, cool air produced by the evaporative
cooler helps your body ventilate naturally.
Evaporative cooling helps maintain natural humidity levels,
so wood furniture and fabric fibers do not dry out prematurely.
Evaporative coolers do not require an airtight structure for
maximum operating efficiency so you can leave doors and windows
open.
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