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Hot shower = 2650 light bulbs

How much energy does it take to run a shower?

Enough to power about 2650 light bulbs! More than the total electrical power to many homes.

How much could you save by switching to a low-flow shower head?

70% - enough to power about 1857 light bulbs!

How about short showers?

If you take a 5 minute shower, that uses enough energy to power 2650 light bulbs for 5 minutes, or about 220 bulbs for one hour.

I'm cold!

Wear warmer clothes, turn up the heater, or even cozy up in front of 2000 light bulbs - you'll still save energy, compared to warming up in the shower.

Save more, greater comfort

Enclosing your shower can cut drafts and make your shower more comfortable, even with less energy, and you comfortably turn off the water while sudsing. This site shows one way: http://www.instructables.com/id/Cozy-Low-Energy-Shower. I've taken a simpler approach - I hung a shower curtain above the door to my shower.

Calculations

The calculations are based on:
  • 5 gallons/minute for a normal shower,
  • 1.5 gallons/minute for a low-flow shower head,
  • 3.8 liters/gallon
  • 4187 Joules to heat 1 liter of water 1 degree C
  • heat water from 40 to 104 degrees Fahrenheit (30 degrees C)
  • 1 Watt = 1 Joule/second = 60 Joules/minute

    Hence, the wattage needed to continously heat water for a normal shower is

  • 5 * 3.8 * 4187 * 30 / 60 = 39776.5 watts

    For comparison, that corresponds to about 2651 15-watt compact fluorescent light bulbs.

    That 40 kilowatts is more than the total electrical capacity of many homes. The typical standard for modern homes is 100 amp, 220 volt service (see this link), or 22 kilowatts.

    Installing a low-flow shower head saves 70% of that, 27844 watts or 1857 bulbs.

    How many incandescent bulbs?

    A 75 watt incandescent bulb uses as much power as five 15 watt fluorescent bulbs. That heavy shower would power about 530 incandescent bulbs.

    Caveats

    At different times of the year, and in different parts of the country, you will heat water more or less than 64 degrees. E.g. if the ambient water temperature is 72 degrees, then cut everything in half.

    This does not consider conversion losses (when producing electricity), transmission losses, or the energy cost for delivering gas or oil to homes.

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