Inexpensive Home Building

Cut through the jargon and nonsense of home building and house construction by starting from zero dollars and trying to figure best-value bang-for-your-buck when choosing construction methods or construction materials. My research might answer some of your questions and at other times perhaps you have the knowledge or experience to post the answers to my questions and thereby help others too. The goal is an affordable and sustainable home for all.


Wednesday, April 04, 2007

Real Power Usage of Appliances (Wattage)

Do not estimate when you can measure.

Guessing can cost you money.

The Kill-A-Watt meter recorded the following results:

  • The “1875W” hairdryer used only 1360W on high and 390W on low.
  • The toaster-oven and coffee-maker were the next biggest loads, in the neighborhood of a kilowatt (kW), but, like the hairdryer's load, these are short duration uses. Brewing 4 cups (1/3 pot) took 5 minutes and the hot plate measured "zero" watts, so a 2-hour total recorded 0.16kWh.
  • The “dorm” mini-cube refrigerator totaled about half a KWh in a day, similar to a constant 22W load but you need 10 times that power capacity because refrigerators are start-stop with a kick-start surge.
  • I did not “benchmark” the computers to record their maximum loads. Normal” was the spike of opening a program or application (browser, word processor) although other active use was sometimes 10-20W less. The desktop does not include the monitor.
  • The "40W" fan used only 15W, close to only a third of its rating.
  • The radio at maximum volume did not draw enough to register above zero on the meter (using an AC adapter to power the radio).
  • The "Actual" numbers in the table are watts (W) observed on the meter, sometimes rounded up a few watts. The meter is less accurate near zero. Anything with an electronic remote control or a non-battery clock is using some power even when "off" (phantom load)--unless you use a "hard off" (for lack of a better term) such as a power-strip switch.






From IHB


Kill

-A-

Watt

Data


(c) 2007







Appliance

Rating (W)

Actual Peak High

Actual Start Boot

Actual Normal

Actual Idle Low

Actual Sleep ”Off”

Coffeemaker drip

1000

820

740

800

0

0

Laptop 150MHz

45

?

31

31

21

1

Laptop 2400MHz

90

?

85

60

25

3

Desktop 900MHz

?

?

60

55

35

2

Fan 4in 1-setting

40

15

NA

15

NA

0

Fan 20in 3-sett

?

170

NA

120

85

0

Hairdryer 2-sett

1875

1360

NA

NA

390

0

Monitor CRT 17in Energy Star

75

75

75

60

NA

0

Radio 2AA cell

?

0

0

0

0

0

Refrigerator 1.7cuft 1/25hp

?

215

215

80

?

0

Toasteroven

?

1150

1150

1100

?

0

2 Comments:

At 5:02 PM, Anonymous Sarah said...

I've been labeling my appliances with their wattage under phases of use. Like the personal fan, low and hi, versus the box fan's low/med/hi. This helps me make instant decisions by reminding me that use of the appliance will cost X.

Great blog, by the way - I'll be linking your posts.

 
At 8:30 PM, Blogger J at IHB and HFF said...

Sarah,

Hello and thank you. Labeling is a good idea, especially with multiple people in the house.

Thank you for the visit.

 

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