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Monitoring Household Electricity

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Here on Maui electricity is rather on the pricey side and as my household here is hitting the 10 year mark a lot of the household appliances are starting to limp or downright fail. It’s getting to be time for replacements. As I do so I started to pay attention a little more to energy usage of the components.

So a week ago I picked up an electricity usage monitor as an exercise in better understanding energy usage in my house:

P3 International P4460 Kill A Watt EZ Electricity Usage Monitor


and I’ve been plugging this thing into various outlets and hooking up a bunch of different appliances to them and monitoring electricity usage. It’s interesting  to see what household appliance and components actually consume in terms of energy – there are definitely quite a few surprises.

Here are a few devices and their energy consumption in a roughly 24 hour time span (unless otherwise noted):

Laptop Computer 0.5 kwh
External (second) Monitor 1.2 kwh
Office Main Plug
Comp, Monitor, Router, modems, USB hub, monitor switch
2.3 kwh
Refrigerator (new) 2.2 kwh
Regrigerator (old) 4.5 kwh
TV (roughly 3 hours) 0.6 kwh
Living Room AV plug (roughly 3 hours)
(TV, DVD, Stereo, Media Laptop)
1.1 kwh
Power Off AV plug (overnight) 0.3 kwh
2 100W Music Amps for 4 hour Jam Session 0.3 kwh

The numbers are a bit surprising in some cases although this falls in line with my monthly energy usage that I see on my bill I use somewhere between 300 and 330 kwh a month in the house which is around 10/12 kwh a day.

Interesting is that the computer’s energy usage is fairly light even when in full operation for 10 hours or more and sleeping the rest. The monitor is the real energy suckage though which has 2.5 times the usage of the computer. All the little boxes we all have – router, cable modem, VOIP Modem, USB hub a couple of other switches all take up another 0.6kwh in that timeframe. It’s not a lot but it competes with the Refrigerator which I wouldn’t have thought – I always thought that office energy usage would be pretty light, but it’s amongst the most energy I use.

The Refrigerator – not surprisingly – uses the most energy of any appliance. It’s warm here on Maui with 80+ degree daytime temperatures and the fridge has to keep its base temperature through it so it’ll probably work a bit harder than it’s spec’d rating which is supposed to be 474kw a year – clearly that’s NOT going to happen (well if I go away for a half a year maybe <g>). I recently bought a new fridge and it’s interesting to compare the old and new ones. The new one uses less than half what the old one did.

Also not surprising is that my LCD TV (42”) uses a lot of energy. Those big screens eat up electricity regardless of that energy star logo on the thing. Also to be expected. What sucks though is that when the device is off sitting over night nearly a third as much energy doing nothing while in standby mode. Yup I had 0.3 kilowatt hours just letting the thing sit at night until 12 hours later in the morning. Everything was turned off, but it’s of course in ‘standby’ mode. The TV still has an LED in front, and stereo, DVD player and other things all have their LEDs on and burning. That probably doesn’t account for the energy usage alone, but it really bites that appliances these days don’t have a way to turn them off completely short of disconnecting them or plugging them into a power strip and turning everything off (which doesn’t work with anything that requires recording and time which I don’t have). As a result I started switching off the switch on the power strip – if I remember.

Either way all appliances these days seem to have this wasteful standby mode. My dishwasher has LEDs that say it’s clean (and it gets confused often enough when the door is closed to start up), the Microwave has blinking lights, the stove does too. All in standby mode with no way to really turn off except unplug or kill the power completely. Lame especially for things like TV, stereo that once off have really no reason to be in standby mode.

Worth looking at Energy Usage?

Now all of this might sound like overkill and it probably is. While electricity is pretty expensive here the actual cost of a kilowatt hour on a bill still amounts to little more than 30 cents. The biggest chunk of my bill are actually base charges, plus energy surcharges with the actual kilowatt hours not being that important (this is how they get you here anyway). In fact looking at my bill I can’t see a damn thing that actually tells me my actual per kilowatt energy costs. Everything is mumbo-jumbo’d with surcharges – probably just to keep people from figuring out exactly what the energy charges are.


I can guesstimate though since I have a few months without any energy usage (because I’m on the mainland then). So even if the entire amount is used the electricity still costs no more than 38 cents a kilowatt hour. But it’s actually less when removing surcharges and other crap that isn’t directly tied to usage. Most likely this will be a way for utilities to get around in the potential case where people start feeding back to the grid. Low kwh charges and high surcharges that aren’t paid back to users.

It’s hard to think that cutting back a few kwh here and there is going to make a big dent on the budget. But then it isn’t only about the bottom line, but becoming a little more aware of what the actual energy usage in the home is and what can be done to effectively reduce it within reason. It’s been useful to put some numbers with actual energy consumption and see them in relation to daily tasks and what energy usage is associated with them. Certainly it can’t hurt to reduce energy usage as much as possible when within reason.

One of the reasons I started looking into this about late last year is that I was thinking of setting up solar for my house here. Clearly we have plenty of sunshine and it would be nice to be somewhat/partially self-sufficient. But looking at my actual energy usage (which I suspect is fairly light compared to most people – especially if you live somewhere where house heating or cooling is required) even this small energy budget would be very expensive to cover with solar for self-sufficiency.

I suppose I’m glad I’ve put this off for some time. I suspect that there will be more improvements in solar technology and public interest in the solar energy sector in the not so distant future as there’s more politcal motivation to move to alternative energies (hopefully). Hopefully this means that prices for the technology will get a little closer to affordability within reasonable range of potential budget benefit <g> and not just as a good faith gesture that it is at this point.

Posted in Personal  

The Voices of Reason


William Kapke
December 06, 2008

# re: Monitoring Household Electricity

I've been looking at doing this exact same thing for quite some time... I just hadn't found a device to monitor it like the one you have above. Do you like it? Do you think it is accurate?

So I gotta say... I've been checking here for answers/ideas about software engineering/architecture for over 5 years- but I never woulda guessed I'd find THIS info here!

.. sooo thanks for posting your randomness too. :)

William Kapke
December 06, 2008

# re: Monitoring Household Electricity

...also- what kinda craziness you doing in December?

Are you a Christmas light fanatic!?

Rick Strahl
December 07, 2008

# re: Monitoring Household Electricity

@William - the device is Ok but it could be a lot better. The problem is that it only works when it's plugged in and it's not always easy to read values off while it's plugged in at some odd angle behind various furniture <s>... It does have a battery so you can unplug it and then look at the values somewhere more convenient but it sure would be nice if the built in battery would allow it to work without being plugged in.

Otherwise the thing is very basic and simple. It does the job.

As to December - that's a great question. I don't know. I think I had a few guests last year in December and there was lots of extra washing machine action going on. Or maybe I forgot to turn off the stove or something. :-}

Anand Narayanaswamy
December 07, 2008

# re: Monitoring Household Electricity

I think Refrigerator (new) with double door (separate freezer) consumes more power than old ones. Water pumps also consumes more power in India.

Anand N
Microsoft MVP

December 07, 2008

# re: Monitoring Household Electricity

In my case, it doesn't matter a few bucks up or down, but if all the people care a bit about being more efficient, it's becomes necessary to burn less coal/gas/petroleum, and you can reduce the overall contamination.

Steve from Pleasant Hill
December 07, 2008

# re: Monitoring Household Electricity

Solar technology makes leaps every few years. PG&E here in CA is required to purchase any excess you produce but cannot consume.

But one always has to compute the 'start up' costs vs. long term payoff.

That is one confusing electricity bill...

December 07, 2008

# re: Monitoring Household Electricity


On Oahu, I feel your pain. We noticed our bill ever increasing, so we decided to just unplug the server, a printer and an extra computer when not in use and that cut our daily kilowatt usage by 1-3 a day. We purchased a 24" IMac a while back and I am curious to its power usage. Thanks for showing how much your music amp uses. I play guitar as well and I have a Marshal 65 and an old Fender Amp I purchased in Germany in the 80s and was wonder how much power they use.



Eber Irigoyen
December 07, 2008

# re: Monitoring Household Electricity

dude, you live in Hawaii!?

I was just there in Maui a few weeks ago

been thinking about solar power options my self for a while, but I'll have to study the efficiency of that here in Utah

Rick Strahl
December 07, 2008

# re: Monitoring Household Electricity

@Eber - Solar is still so damn expensive and fairly inefficient although efficiency is finally reaching upward of 30% energy conversion. However most Photovoltaic systems you buy today do much worse. It takes a lot of coverage and $$$ to generate enough power to be self sufficient and currently the return on in investment is very unfavorable. The projected break even points for current systems are usually given as 15-20 years (barring extremely drastic energy rate hikes).

Still I've been thinking about this - I think energy is going to become much more expensive in the not so distant future, so it might be a good idea to start planning ahead. I'm hoping the new administration will provide more incentives for solar and start more technology investment in this area to bring prices down... we'll see.

Douglas Osborne
December 08, 2008

# re: Monitoring Household Electricity


When I remodeled my basement, I junked the oil burner and outside central air unit for a geothermal system. The heat and the air conditioning work great - I have the lowest allowable electric rate from PECO because I'm using renewable energy - our biggest electric bill in the past 6 years was $259 - and this is in PA where we have snow on the ground as of this morning.

Here's the website for my unit - http://www.waterfurnace.com/.

I have to put your monitor on my beermeister and see what that is costing me...;-)


Alex Feldstein
December 08, 2008

# re: Monitoring Household Electricity

Since I sold the house and moved to an apartment a few years back, my consumption dropped dramatically. I am in Florida where we can drop the A/C for a few months (it's been off since October). My electric bill is now very low until March.

I still wonder what the refrigerator, stove, server, PCs (3) and TV consume. I might do what you did to check them out.

December 14, 2008

# re: Monitoring Household Electricity

Interesting! My electric bill is roughly the same here in Pittsburgh,PA. I'm running 3 servers 24x7 with a workstation that goes to sleep when not in use. I always turn off my monitor when I walk away. Working in the Nuclear industry however, and we're designing systems that will reduce the cost of generating electricity. I hope it gets passed along by the Utilities that buy our equipment.

December 18, 2008

# re: Monitoring Household Electricity

Things are getting rather expensive over here in the UK as well, although I have switched to a company called Utility Warehouse who seem to be pretty sharp at keeping elec and gas prices low.

What I find most amazing is that our Government want us to use Green energy, but after some investigation I found that the price to install and setup things like solar power is crazy and it would take me probably a decade to get any return! I mean to sort of incentive is that...

(Just thought I'd have a rant!)

Mitchel Sellers
December 26, 2008

# re: Monitoring Household Electricity

Wow, that is nuts. We pay $0.08 per kilowatt here in Iowa, i didn't realize how cheap our costs really are!

January 05, 2009

# re: Monitoring Household Electricity

We use roughly the same gadget in the UK. Really useful. My house tends to have a "run rate" of about 0.3 kwh peaking at 2.4 kwh if the kettle is on for a cup of tea (very British). The really frightening thing is how much energy that actually is - I'm sure you've tried the high school experiment of trying to power a 100w lightbulb from a bicycle wheel (pretty much every science museum will have the same experiment) and its just about possible for a fit guy/gal for about 30 seconds. Our household is buring the equivalent of 3 of those just sitting and reading a book.

With regard to standby - its a pain but we've put in individually switchable plug blocks so we can turn off those bits and pieces we know were not using; watching TV without the DVD-R ? fine, watching a movie from DVD with home cinema, fine, we just have to remember to switch off the stuff we're not using. My dictum has been that I should be able to walk around the house after dark and see no little glowing lights anywhere. Only issue is with the DVD-R which takes a good 60 seconds to boot up, but I can live with that.

Derek H
August 02, 2009

# re: Monitoring Household Electricity

I've put my cable modem & Apple wireless router on a plug in timer that switches them off at midnight and on again at 0800, when I start work. The Computer is off the same block too. I used to have the router and modem on 24/7, so I'm hoping to save a bit. I also have a separate fridge, and separate freezer. I'm going to look at a getting a single unit that uses only one compressor.

October 22, 2010

# re: Monitoring Household Electricity

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