Poor maintenance can reduce efficiency of ventilation systems by as much as 40 percent.
The ventilation system of your dairy consumes about 21 percent to 24 percent of the energy used on the dairy. This means you should be looking at the efficiency of your fans.
Fan efficiency is commonly measured as cubic feet per minute (cfm) of air per watt (W) of electricity consumed to give a cfm/W number. Several factors affect fan efficiency, including blade design, housing design and motor efficiency. Therefore it can be said that “not all fans are created equal,” and you often “get what you pay for.”
Source: John Tyson, Penn State Extension Dairy Team, June 2012 Penn State Dairy Digest