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The Parker Ranch installation in Hawaii

Certification for C&I Fans

6-4-2015
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• Sampling requirements: Typically at least 2 units are selected at random to be 

tested

• Each sample is tested in accordance with the product’s test procedure

• To account for variations in materials, the manufacturing process, and tolerances 

when manufacturer’s are testing, manufacturers must use statistics to determine an 

appropriate rating range

• For example, product making representations of energy consumption:

• Determine the mean of the sample:

• Determine the upper confidence limit of the true mean divided by 1.05: 

• Representations of energy consumption must be greater than or equal to the 

whichever is higher, the UCL or mean. 

How to Rate a Basic Model

x� = mean

n= number of samples

xi = efficiency measured per sample

xx̅=

1

nn ∑ xxii

nn

ii=1

UCL = xx̅+ tt0.975 ×

ss

nn

UCL = upper confidence limit

t

0.975 = t statistic for the 97.5% one tailed confidence interval with n-1 degrees of freedom

s = standard deviation
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FER Representations for Com. and Industrial 

Fans

• For each fan model, certify FER at every operating point for which the model 

is going to be sold

• Two methods for calculating FER at each self-declared operating point: 

1. FER = tested BHP + default motor losses + default transmission 

efficiency+ default controls losses

• Test two samples at the given operating point and apply default values 

to determine FER for each unit in the sample (FERa, FERb)

• Use DOE statistics to calculate the mean and UCL from FERa and 

FERb, determine allowable range for selecting a representative FER 

• The representative FER for this operating point of a given fan basic 

model is selected from this range and certified to DOE. This same 

value must be used in all public representations.
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2. Wire-to-air test

• Conduct a wire-to-air test for two samples at the given operating point to 

determine the FER for each unit in the sample (FERc, FERd)

• Use DOE statistics to calculate the sample mean and UCL from FERc

and FERd, determine allowable range for selecting a representative 

FER 

• The representative FER for this operating point of a given fan basic 

model is selected from this range and certified to DOE. This same 

value must be used in all public representations.

FER Representations for C&I Fans
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Illustrative example based on current DOE method

• Example for method 1 at one operating point 

– Test two samples at the given operating point and apply 

default values to determine FER for each unit in the 

sample (FERa, FERb)

BHPa= 5.92 add default values FERa= 7.34

BHPb= 5.87 add default values FERb= 7.22

– Use DOE statistics to calculate the mean and UCL from 

FERa and FERb, determine allowable range for 

selecting a representative FER 

xx̅=

1

nn ∑ xxii =

1

2

× 7.34 + 7.22 = 7.28 nn

ii=1

UCL = xx̅+ tt0.975 ×

ss

nn

×

1

1.05

= 7.28 + 12.71 ×

0.084

2

×

1

1.05

= 7.66

Energy Conservation Standard ≥ Representative FER ≥ 7.66

FER Representations EXAMPLE
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Illustrative example based on current DOE method

• Example for method 2 at one operating point 

– Test two samples at the given operating point to 

determine FER for each unit in the sample (FERc, 

FERd)

FERa= 7.30

FERb= 7.18

– Use DOE statistics to calculate the mean and UCL from 

FERa and FERb, determine allowable range for 

selecting a representative FER 

xx̅=

1

nn ∑ xxii =

1

2

× 7.30 + 7.18 = 7.24 nn

ii=1

UCL = xx̅+ tt0.975 ×

ss

nn

×

1

1.05

= 7.24 + 12.71 ×

0.084

2

×

1

1.05

= 7.62

Energy Conservation Standard ≥ Representative FER ≥ 7.62

FER Representations for C&I Fans