Save Energy — Fans

Your home is a giant block of air. This air needs to be moved for various reasons. Fans move air to distribute heated or cooled air throughout your home, provide a gentle cooling breeze, exhaust unwanted air from your bathroom or kitchen. Fans if used properly can be a big aid in comfort and save energy.

Your Home Energy Living Plan

  • Ceiling fans should be used only to blow air upon occupants in the summer, or blow to the ceiling to mix air in the winter.
  • Use bathroom and kitchen exhaust fans only as long as necessary to do the job.
  • Turn off fans when not at home.
  • If you have a whole house fan, make sure it seals tightly when not in use.
  • If your have an attic fan, make sure it is operating properly (see attic ventilation).
Impact of Your Energy Saving Actions

About 11% of the average US home’s annual utility bill is for air conditioning. This percent is an average of all the United States, where many homes do not have A/C or are in northern climates, so if you have air conditioning then your percent may be higher. Using fans to holding off on running the air conditioner can have a significant impact.

Infiltration accounts for 28% of heating and 16% cooling energy. Insuring a good seal on your whole house fan can have an impact.

How Energy is Lost

All fans use energy. However the energy to run a fan is small; it can be less than 100 watts. If the operation of a fan prevents the running of more energy intensive equipment like the air conditioner, then energy can be saved. The problem is overusing fans. You may have the ceiling fan on in order to not turn on the cooling. A ceiling fan is only effective when blowing on someone. Exhaust fans may run long after they have done their job. While most fan motors draw about the same energy as a light bulb, just like a light bulb the energy adds up if left on.

You may have a whole house fan. They can be effective in cooling the house, but they are a big hole in your ceiling. If the fan does not seal tightly, air can leak past just like a leaky window or door.

Fan Characteristics

A fan or in some cases a blower is a motor that rotates blades causing air to flow. Technically a fan increases the air pressure forcing air to increase in velocity. Fans used in residential applications do not have to create very much pressure to accomplish they goal. Therefore, the energy needs are small. Bathroom, most portable and most ceiling fans use about 100 watts or less. This sets the stage for saving energy.

Ceiling fans are mounted from the ceiling and blow air down towards the floor. Their cooling effect is from the manner in which we lose heat from our bodies. As air velocity increases, our sweat evaporates faster making us feel cooler. Ceiling fans do not cool the air, we just feel cooler from the breeze. Energy is saved only when the use of ceiling fans keeps the air conditioner off. If the fan is not blowing on someone, then they are not serving any purpose and are wasting energy. Do not run ceiling fans if no one is in the room. Do not run ceiling fans when the air conditioner is on. If it feels more comfortable with fans running when the air conditioner is on, then you may have an air distribution problem, see air distribution.

In the winter warm air will rise towards the ceiling. In high ceiling rooms the air near the ceiling can be several degrees warmer. By reversing the ceiling fan, air is blown up to the ceiling forcing the warm air back down lower into the room. This can help keep the room warm, however it could also be a sign of poor air distribution. For rooms of normal ceiling height (8 feet) the air distribution system should be able to prevent any significant warmer air at the ceiling.

Bathroom and kitchen exhaust fans are to remove obnoxious fumes and moisture. Insufficient bathroom exhaust can result in mold or mildew damage in bathrooms. The small amount of energy to run them is worth the protection. However, they should not run for long periods of time. Air can also leak out through the exhaust fans. The fans have dampers that close, but they may become stuck open.

Instead of operating several ceiling or portable fans a whole fan pulls air through the whole house. Located in the ceiling, they pull air in through windows (which should be opened) and exhaust through the attic. The openings at the fan is as large as a window. If this opening does not seal when then fan is off, then air can leak out. The whole house fan should not run when the air conditioner is on.

You can affect the ability of a fan to blow air. If you block or hinder the flow of air then the amount of air will decrease. This can easily happen with exhaust fans, portable fans, whole house fans, or your fan in the central heating/cooling unit. The fan becomes less effective if its airflow is decreased. For most of these fans the energy will increase as the airflow is blocked. So you get less and pay more. All propeller type fans have this characteristic. Centrifugal fans, like the one in your central heating/cooling unit will decrease energy use if blocked.

Do not forget about the fan in your central heating/cooling unit. This fan distributes air throughout the house (see air distribution for more details). Do not block any supply or return grilles. Also change filter regularly. Also the fan in the outside unit of your air conditioner must be kept clear of any debris (see air conditioning for more information.)

Energy Solutions Explained

Use fans as needed. However, they will not save energy unless they prevent the use of air conditioning.

Speak Your Mind