The Virgin Islands Water and Power Authority (our power company) is seeking a 40% increase in power costs come July. We are already paying $0.33/kWh for residential areas, much higher than most areas of the US (3-4 times higher than many areas).

From what I've heard, the high rates are caused in part by people stealing electricity. Many residents will routinely unhook their meters, only to re-connect them the day before someone comes out to read the meters. WAPA has been cracking down on this lately, and most of the boxes now have tamper-evident clasps and are read automatically from the office. In addition, they burn oil at the power plant, so they are highly affected by increasing oil prices. And they seem resistant to alternative energy ideas for some reason. It seems like a wind farm would be an obvious natural source of energy on an island where we have fairly constant 10mph+ trade winds all year round.

This rate hike will make alternative energy much more viable, of course, so we may have to reconsider solar power in a much shorter timeframe.

In preparation for this, I decided to spend part of my weekend figuring out where we use all of our electricity. Our bill runs around $800/month, so surely there must be something we can cut back on. I measured the energy usage of everything in our house that consume electricity. I use a few different methods to do this.

First, I purchased a Kill-A-Watt power meter and plugged various items into it. It displays instantaneous usage in Watts and total usage in kWh over any period of time.

1. For devices that are plugged in and operate all day long at the same power levels (e.g. routers, telephones, etc.), I simply took a Wattage reading and added it to the spreadhseet.
   
2. For devices that are off or idle most of the time but come to life for periods of activity (e.g. washing machine, microwave,
   computer, etc. - most things that are plugged in), I took a Wattage reading when the device is off (many devices consume a small amount of power even when they are off!) and then when it was operating. I then estimate approximately how many hours per day those devices were operating.
   
3. For devices that fit the previous criteria but are difficult to estimate usage (e.g. water cooler, wine cooler, washing machine, etc.), I measured one cycle if possible (e.g. wash one batch of clothes). For continuous things like the water cooler, I plugged them into the Kill-A-Watt meter for a day and measured how many kWh they used.
   
4. Lights are easy. Just read the Wattage numbers on them and multiply by the number of lights. With compact flourescent (CF) bulbs, be sure to read the actual Wattage and not the effective Wattage. For example, our driveway lights are 7W bulbs, but they replace incandescent bulbs of 35W and produce the same amount of visible light (incandescents waste a lot of power by producing light that's not visible to human eyes and by producing light over a broad spectrum).
   
5. Ceiling fans are also easy. I found a chart online that gives 52" fans as using 90W and 36" fans as 55W.
   
6. For some appliances that weren't easy to get to the plug, I looked up their rating at EnergyStar's website.
   
7. For hard-wired appliances that had power ratings on them, I used those. Some were listed in Watts, but others were listed in as horse-power or Amps. A horse power is 746 Watts, so that's easy. (Our water pump is 1/2 HP, for example.) To convert Amps to Watts, you simply multiply by the Voltage. So you have to know if the appliance is on a 120V or 240V circuit. For example, our 17.7amp air conditioner on a 240V circuit uses 4.2kW at peak power. (This is a very powerful and efficient Mitsubishi mini-split air conditioner.)
   
8. To further confirm the energy usage a few key appliances like our pool pumps and air conditioners, I took a meter reading. To do this, I turned off as much electricity as I could in the house, especially anything that might come on intermittently and ruin my measurement. This required that I turn off the circuit to the refrigerator and turn off all A/C. I then measured how long it took for the power meter (installed by the power company at the edge of our property) to make one full rotation. One rotation is 0.01kWh or 10Wh. The baseline measurement with everything off was 54.39s/10Wh. Since one hour equals 3600 seconds, we can cancel out seconds and get: 54.39/36000W. Take the reciprocal to get: 662W. That's our instantaneous power usage with all the large power-consumers turned off. I then repeated this calculation with the appliance in question turned on to come up with a total instantaneous Wattage. Subtract the baseline Wattage to get the power that the appliance is using.
   

Conclusions

First, I found that we are doing a lot of things efficiently, already. For example, we use a solar hot water heater with a solar-powered pump. So our hot water is effectively free. The sun heats the hot water to excess of 160 degrees, seriously minimizing the amount of supplemental heating the clothes washer or dish washer need to supply. Second, we use propane for cooking and clothes drying. It is much cheaper to produce heat from propane than electricity, even at mainland US rates.

In addition, we've recently upgraded some appliances to very energy efficient models. We upgraded our washer and dryer to Whirpool Duet high efficiency ones. I did a batch of laundry in both and calculated 0.08kWh to wash and 0.22kWh to dry. Even if we do 4 loads per week, it only costs $0.56/mo to wash and $1.24/mo to dry a medium-sized load (including the constant 1W that each appliance uses while inactive). It helps a lot that water and heated water are free due to our rain-collecting cistern and solar hot water. We also upgraded our old Sub-Zero refrigerator to a more efficient Kenmore side-by-side.

There were also some surprises. While I knew that compact flourescent lights saved power, I didn't realize how much power incandescent lights used! For example, in our bathroom, we have a set of 12 40W lights over the mirror. When on, that's 480W, twice as much as my computer! Even if we just use them 2 hours per day when getting ready in the morning, that's $7/month just for those lights. If we forget to turn them off, they cost $4/day or $120/month just for one set of lights!

In addition, our pool pump uses much more power than I suspected. Here's the full breakdown:

• Air conditioning and fans: $306
  
• Computer Equipment: $154
  
• Television Equipment: $35
  
• Lights: $91 (including 9 low-power Sodium security lights that run 12hr/day on a light-sensitive switch)
  
• Appliances: $29
  
• Pool pumps: $182
  
• Other: $3
  

I was also interested in how much power we were wasting on devices that stay on all the time or use power when "off". It was not as bad as I thought. So here is the breakdown looking at that:

• Devices that are off: $9
  
• Devices that are idle or always-on: $36
  
• Devices that are on or being used: $755