BAE Department - University of Kentucky

This program analyzes the costs and returns for investing in high volume low speed fans (HVLS) on a dairy not presently utilizing cooling strategies. The values which are already filled are default values. You can change these values according to your own situation. Yellow cell values are calculated automatically and cannot be changed.

   
Income tax rate
     
Minimum attractive rate of return
     
     
Number of fans
      Choosing the number of fans.
Fan horsepower
    hp  
Efficiency
    decimal  
Cost per fan
$ $/fan  
Total installation cost
$ $/fan  
Electricity rate
$ $/kwh  
Hours of operation per year
       
Electricity cost
$ $/yr  
   
Milk price
    $/cwt
Number of cows
     
Gain in production
    %
Base milk production
    305 day average
Gain from cooling
$ $/yr

    
Net present worth
$ $
Annual benefit
$ $/yr
Payback

   

yrs

 

Choosing number of fans:

Provide cooling fans to increase air movement over the body of the cow. Air should move past cows' bodies at 200 to 400 ft/min. HVLS fans move a large volume of air (up to 88,000 cfm) over a large area (up to 15,000 sq-ft) very slowly (at about 200 to 300 ft/min). At standard speed, a 20-ft paddle fan creates a floor jet about 9-ft deep. Space HVLS fans 60 feet apart over the feed alley. Use the following table to determine the number of fans you need:

Number of rows
Length of barn
HVLS fan
2
120
2
3
120
4
4
120
2
6
120
6
2
240
4
3
240
8
4
240
4
6
240
12

For different size barns, use the analogy between number of rows and length of barn given in the table above to determine the number of fans.

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Adapted By Original Score system Web Version

Updated 06/29/2005

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This page is part of the Biosystems and Agricultural Engineering web at http://www.bae.uky.edu