Dairy Farm Energy Management Handbook - Wisconsin Department ...

and bears a heavier load to achieve the desired amount of cooling,
which costs more in electricity.
In many cases, you can repair louvers that are sticking (in the open or
closed position) just by cleaning them and applying a dry graphite
lubricant to the hinges. Graphite is recommended over oil because it will
not attract dirt as rapidly and thus reduce the maintenance interval.
Any obstruction on the discharge of a fan impedes airflow. In short, fans
with louvers on the outside are less efficient than comparable fans with
louvers on the inside.
You may have to spend some time shopping to find fans with inside
louvers since most fan louvers are built for installation on the discharge
side.
Louvers also come in two basic types: motor-activated and air-activated.
Air-activated louvers reduce airflow 20% to 30% and are less efficient
because fan power pushes the shutters open.
Motor-activated louvers eliminate that problem because the shutters lift
and close automatically. In addition, motor-activated louvers will work
even when dirty or when the joints get stiff, so cold air is less likely to
enter during wintry days.
• Safety guards should be used on fans within reach of personnel to
prevent accidents. The guard supplied by the manufacturer is usually
best because it lowers fan airflow and efficiency very little (usually by
less than 5%).
• Installing thermostats to control the fans’ on-and-off operation saves
energy and increases productivity.
Research has indicated that dairy cows begin to show heat stress at 74°
F with 70% relative humidity (the average relative humidity for
Wisconsin), so it is recommended that the thermostat be set between
70° F and 75° F.
Sanford recommends using a thermostat designed for outdoors in
damp, dusty conditions. He suggests mounting the thermostats out of
the reach of animals but in an area that will accurately reflect air
temperatures around the livestock.