What Does A Kilowatt Hour Mean?

When using electricity in your home, you never think about “how many kilowatt-hours (kWh) am I using to power/charge my __________?”  But the reality is, everything that is plugged into an outlet or hardwired uses power.  That power adds up to what you pay monthly on your electric bill and can get expensive if abused. Being an energy consultant I am often asked, what really is a kWh?  The easiest way to explain this concept is the following:

One kWh of energy is equal to 1,000 watt hours and will power a 100 watt light bulb for 10 hours.

(100 watts x 10 hours = 1,000 watt‐hours = 1 kWh)

Believe it or not, a kWh can go pretty far when you think about it.  Here are some examples of a typical use of a single kWh:

‐ Watch television for 10 hours                                  ‐ Wash 12 pounds of laundry

‐ Work on computer for 5‐10 hours                          ‐ Vacuum for an hour

This chart below illustrates the amount of kWh’s a typical household item uses:

Ceiling Fan                                                                0.075 kWh/hr. = $0.018 per hour

Central Air Conditioning (3 ton‐12 SEER)                3.0 kWh/hr. = $0.72 per hour

Dishwasher, Norm Cycle – Cold Water         1.0 ‐ 2.17 kWh/load = $0.52 per load

Microwave Oven (1,600W)                               0.12 kWh/5 min = $0.028 per 5 min

Energy Star Refrigerator, 17 Cu/Ft                     73.0 kWh/mo = $17.52 per/month

Ironing                                                                               1.0 kWh/hr. = $0.24 per hour

Television > 50" LCD                                                0.22 kWh/hr. = $0.052 per hour

Recording Device – DVR                                        28.8 kWh/mo = $6.91 per month

Computer – Laptop                   0.02 ‐ 0.05 kWh/hr. = $0.0048 - $0.012 per hour 

iPhone 6                                                            3.8 kWh/per full year = $0.91 per year

Golf Cart Batteries (New 48 Volt)       2.8 kWh/per full charge = $0.67 per charge

Tesla Model S (P85D)                          85 kWh/per full charge = $20.40 per charge

*Information Sources:  U. S. Department of Energy (www.energy.gov); Silicon Valley Power (www.siliconvalleypower.com); Concordia Electric (www.concordiaelectric.com). Information provided is approximate and may vary based upon age of appliances/devices and usage.

**Cost per kWh is calculated by using an average SCE customers cost of .24 cents per kWh.