During the summer when temperatures exceed 100 degrees Fahrenheit or in winter when temperatures drop below 40 degrees Fahrenheit, most heating and cooling systems reach capacity. The efficiency of the system decreases when it operates at or near its rated maximum capacity. In other words, the amount of comfort benefit realized is significantly less per unit of electric energy consumed. A great deal of electricity is used and less comfort is achieved.

How does this affect my bill?

  • Significant swings in outside temperature may make your heating or cooling equipment run longer and use more electricity
  • Only a few days of extreme temperatures can cause your bill to be noticeably higher
  • During extreme weather your system will work much harder to cool or heat your home and may not be able to effectively attain the temperature setting you have selected

Winter Cold Weather

During periods of cold weather, portable heaters and strip heaters are among the highest sources of electricity demand. View more cold weather tips.



Summer Hot Weather

Even if you never change your thermostat, cooling can account for 50% or more of your electricity bill during hotter weather. When you lower your thermostat to stay comfortable in humid weather, this causes your air conditioner to run longer which increases electricity use. To save energy, cool your home at 78-degrees or warmer with the thermostat fan switch on "auto." For additional savings, raise your thermostat to 82-degrees or warmer when you're away from home. Also, clean or replace your air conditioner's filter every month to help your unit run more efficiently. View more hot weather tips.

Spring Relative Humidity

Relative humidity is the percentage of water vapor present in a given quantity of air compared to the amount it can hold at its temperature. How does it affect a cooling system and your electricity bill?

Direct Effects

  • The coils of an air conditioning unit collect condensation. The more humid the air, the more water collects on the coils. This results in the unit running longer.
  • The humidity in the air does not change the thermostat reading; however, it does change how much energy is available to cool the house. This results in the thermostat staying at the same setting for longer periods of time.


Indirect Effects

Moisture in the air can cause you to feel warmer and result in you lowering the thermostat.