Here we will
list some of the HVAC System Units and Ratings that you can find in the
brochures or specifications of the air conditioner or heat pump units as
follows:
 Cooling Capacity,
 COP (Coefficient of Performance),
 EER (Energy Efficiency Ratio),
 SEER (Seasonal Energy Efficiency Ratio),
 HSPF (Heating Seasonal Performance Factor),
 Energy Star.
1.
Cooling Capacity
 Cooling
capacity for a room is defined as the heat load in a room that has to be
removed in order to achieve a certain room temperature and humidity. The
typical design is set to 24°C temperature and 55% Relative Humidity.
 The
amount of cooling needed by the space will be used to determine the capacity
of the air conditioner needed. The cooling capacity can be expressed in many
units as follows:
1.1 BTUH
– “British Thermal Units per Hour”:

1 BTU/hr is the heat energy needed to increase 1 pound of water
by 1°F.
1.2 Ton of cooling:
 One ton of
cooling is the heat extraction rate of 12000 Btu per hour. Theoretically
it is energy required to melt one ton of ice in 24 hour.
1.3
Ton of Refrigeration Effect:
 The
cooling capacity of older Refrigeration units is often indicated in
"tons of Refrigeration" A ton of Refrigeration represents the heat
energy absorbed when a ton (2000lb.) of ice melts during one 24hour day.
 The
Btu equivalent of one ton of refrigeration is easy to calculate. Multiply the
weight of one ton of ice (2000lb.) by the latent heat of fusion (melting) of
ice (144 Btu/lb). Then divide by 24hours to obtain Btu/hr.
One ton of Refrigeration effect= 2000 (lb) x 144 (Btu/lb) /24 (hours) = 288,000Btu/24 hours = 12,000Btu/hr
 A
refrigerating or air conditioning mechanism capable of absorbing heat can be
rated in tons per 24 hours by its heatabsorbing ability (HA) in Btu divided
by (24 hr x 12000 Btu = 288,000).
T = HA / 288,000
Where:
T
= tons of refrigeration effect
HA = heatabsorbing ability in Btu
Example#1:
The heatabsorbing ability of a refrigerator unit is 1,440,000 Btu per 24 hours.
What is its ton rating?
Solution:
T = 1,440,000/ (24 x 12,000) = 1,440,000/ 288,000 = 5 tons of refrigeration
effect
2.
COP (Coefficient of Performance)
 This
coefficient is the ratio of the cooling capacity (W) as the output power (in form of removed heat load) versus power consumption (W) as the input power.
COP= Cooling Capacity (W)/Power Consumption (W)
 The
higher the COP, the higher the efficiency of the air conditioner. Usually the
value range from 24 but in recent years, the use of inverter compressors
have enabled this coefficient to go higher than 4.
3.
EER (Energy Efficiency Ratio)
 This
rating was established by ARI or Air Conditioning and Refrigeration Institute
in 1975 for manufacturers to rate their equipment so that consumers or
consultants can tell the cooling efficiency of the air conditioner by just
looking at the specifications provided.
 This
rating is obtained by dividing the cooling capacity (Btu/h) with the input
power (Watt). The rating points are at 80 °F dry bulb/67 °F wet bulb indoor
temperature and 95 °F dry bulb/75 °F wet bulb outdoor temperatures.
 For
instance, if you look at the brochure and the unit has a Cooling Capacity =
25,000 Btu/h and Input Power = 2,400 W,
EER = (25,000 Btu/h)/2400W = 10.42
 The
larger the value of EER, the more efficient the air conditioner is.
Therefore, choose a bigger EER if you are comparing between two equipment.
 The
EER has a limitation in that it is measured only when the unit is in
steadystate condition. The starting up and shutdown cycles are not included
in the calculation. Therefore, this rating does not give a complete picture
of the efficiency of the unit. A better efficiency ratio known as Seasonal
Energy Efficiency Ratio or SEER is developed.
4.
SEER (Seasonal Energy Efficiency Ratio)
 This
ratio is rated by AHRI (Air Conditioning, Heating and Refrigeration
Institute) and manufacturers' equipment ratings are published in their
catalogs. This ratio is more accurate as it takes into consideration non
steady state conditions such as the startup and shutdown cycles of the air
conditioner.
 This
ratio is obtained by dividing the total cooling that the equipment is able to
provide over the entire season (Btu) over the total energy in Watthours it
will consume (Wh).
SEER = [Total of Btu/h cooling outputs at all test
conditions]/[Total of all Watt inputs at all test conditions]
The
unit of SEER is Btu/W.h.
 The
COP of a machine can be found by multiplying the SEER by a factor of 0.293
COP = SEER X 0.293
 In
choosing the SEER, the choice is always to go for a higher SEER as it is more
efficient equipment. The tradeoff in choosing a higher SEER is that usually
the initial cost of the equipment will be higher.
 All
central splitcooling system produced in the US must have this ratio
effective Jan 23, 2006. In order to ensure more efficient units are produced,
a minimum SEER of 13 has been stipulated except for window units which has a
minimum SEER of 10.
 You
can find the Watts Input, Cooling Capacity as well as the SEER information on
the label which is usually a metal plate that is attached to the heat pump
unit. If SEER is not provided, a simple calculation can be done.
Example#2:
If
the label displayed Cooling Capacity = 5000 Btu/hr and Watts Input = 600 W.
Solution:
SEER
= [5000 Btu/hr]/[600W] = 8.3
Example#3:
If
another 2.5ton air conditioner requires 2 kW of electrical power, what is
the SEER?
Solution:
1
ton of refrigeration is 12,000 Btu/hr.
SEER
= [2.5 X 12,000 Btu/hr]/[2,0000 W] = 15
5. HSPF (Heating Seasonal Performance Factor)
 This
ratio is used to determine the efficiency of air source heat pumps equipment.
It applies to the heating mode by which the total heating used during the
entire season is divided by the energy in Watthours that it consumed.
HSPF =the total heating used during the entire season in Btu /
the energy in Watthours that it consumed in KWH
 A
ratio of greater than 8 is considered efficient equipment. However, the
advancement of better control and inverter compressor has enabled units to
have HSPF up to 13. The higher the HSPF, the better the unit is.
Example#4:
A
ductless split unit heat pump delivering 100,000,000 Btu during the entire season
and consuming 12,000 kWh. Calculate its HSPF?
Solution:
HSPF
= 100,000,000 Btu/12,000 kWh = 8.33
6.
Energy Star
 This
rating for an equipment shows that the equipment is designed to save energy
hence reducing your electricity bills as well as protecting our environment. The
below figures show the SEER and EER equivalent to each star rating.

Energy Star SEER Rating 

Thank you
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