This page is a good idea, but the proposed spreadsheet for launching the home audit has a couple serious problems. Since I can't edit the spreadsheet itself, I'll put my beefs about it here.

  • Watts = Volts x Amps? It's not that simple. With A.C. power, that only works with a purely resistive load like an incandescent light bulb or a space heater. The major electricity users in a home - fridge, air conditioner, anything with a transformer/motor/compressor - are reactive loads. The voltage and current sinusoids are out of phase, you can't just multiply the rms volts and amps together. This is obvious to an electrical engineer (like me), but the average visitor to this page won't know that. It's best that they don't worry about volts and amps, and just enter the watts, either from the appliance label or measured with a wattmeter.
  • As most folks don't have a wattmeter, I think it would be easier if you pre-populate the spreadsheet with a list of appliances, light bulbs, etc. and their typical wattages already filled in. Then the user only has to enter the quantity of each appliance (leaving it 0 if they don't have one) and the number of hours they estimate they use it. I think a good start would be a list like this: http://web.archive.org/web/20090204111342/http://bluewaterpower.com:80/rates.asp?link=7 .
  • I guess the phantom load column is ok, but I really think it's overhyped these days. Standby power seems to be the villain de jour, but my own audits of my home and others show that phantom loads are very minor compared to the very visible household electricity hogs: air conditioners, refrigerators, water heaters, waterbeds, and lights that are left burning all night.

(A Wikipedia contributor, passing through...) 68.78.97.236 17:58, 30 January 2007 (PST)

  1. You are right that P=I*V only for ohmic devices, and that phase difference results in a power factor less than 1. But when the electric company charges for kW, they are actually charging for apparent kW, aka kVA. Therefore if you are on the grid, the watts you are paying for are actually volt*amps, but when you are off the grid your point rings very true. Another factor that makes your point more pertinent is that the amps on the label of most appliances is the max current for legal purposes. I think the best answer is to have seperate spreadsheet tabs for on-grid vs off-grid. All of this needs to be addressed on the main page and I appreciate you raising your points here.
  2. Thank you for the great idea. I am a little reticent to make the spreadsheet long enough to prepopulate it with common appliances, but I really like the idea of having that information in the spreadsheet. I will start a page, Common energy consumption of appliances, to start compiling this information.
  3. I consider standby power to be a phantom load. I started Phantom loads to discuss this further.
Thank you, I greatly appreciate you stating your concerns here. --Lonny

It is good that topic of home energy audit is being discussed.Tutoring common man with electrical energy conservation ideas ,which they can practice,is welcome

I want to add only one point:

common man understand Power in watts so it is better to stress usage of low watage CFL lamps electronic chokes comparing with Incandescent and Fluorescent lamps and conventional chokes with respect to their comparable luminous intencity and how they provide electricity conservation and reduction in electricity bill. [Abraham - consultant Energy conservation and Management]