Understanding Your Energy Bill Part #1 — Why Don’t They Write Energy Bills in English?

Having just launched our Energy WatchDog Program, I’ve had the…well I don’t want to say pleasure but let’s call it opportunity…to become familiar with energy metrics – kilowatts and kilowatt-hours and the like. Personally I would like to have words with the person who invented the term “kilowatt-hour” as it does not necessarily refer to an hour, but the consumption of energy over a vague period of time which could literally be an hour, 24-hours, a month, or any amount of time which floats your boat.

For example, a 60-watt bulb will use 60 watt-hours (or 0.06 kilowatt-hours) of energy in an hour, but you could also say that it will consume 1,440 watt-hours (or 14.4 kilowatt-hours) in 24 hours. Whether or not energy consumed was during an hour, a day, or a year, you will still see a watt-hour or kilowatt-hour (kWh) designation. And that’s just the start of the confusion.

Electric Meter

One helpful blog article that I found recently does a good job explaining the concept of watt versus watt-hour and also has some clever-cute “screw in a light bulb” jokes to boot. The blog, “What is a Watt, Anyway? Understanding Energy and Power Metrics” posted by Tristan Roberts on BuildingGreen.com discusses the following:

  • Watts are basically the miles-per-hour measurement of the electrical world–they tell you how fast the electrons are speeding down the highway (i.e. a 60-watt bulb is going 60 watts per hour – that’s fast!). A watt is a measure of speed of electrons, otherwise known as “power.”
  • While a watt is a measure of power, a watt-hour is a measure of energy. When you get your utility bill, the electricity you’ve used is measured in kilowatt-hours (kWh) or kilowatts consumed over a period of time. Energy is defined as the capacity to do work, such as creating heat, light, or motion. Kilowatt-hours is the measurement of energy consumed over a period of time.
  • Commercial and industrial facilities typically pay “demand charges,” which are calculated based on their peak power draw (usually measured in megawatts, or MW), which compensates the electric utility for ensuring that it has enough power available to meet that demand.

Though this article touches on Demand Charges, I will be exploring them further in future blog articles. An important thing to know about demand charges is that they can be fairly easily reduced using programming and sequencing strategies. More on demand charges to come…