Elecricity Audit: Lessons Learned

Just in time for Earth Day and after 2 months of Kill-A-Watt'ing the electrical audit of our home is finally complete! There were many eye-opening findings which prompted me to make lots of changes, and the results on our electric bill have already been well worthwhile.

Here is an Open Document spreadsheet with all of my data (you can use OpenOffice to read it):

http://www.cyberarmor.net/data/downloads/other/electricity_usage.ods

Here is an OpenPDF version of it for you folks that are still using MS Office and can't work with Open Document formats:

http://www.cyberarmor.net/data/downloads/other/electricity_usage.pdf


Here is a list of the things I learned:

a) My old cabbage patch of server equipment was eating our lunch not just on electricity but on HVAC as well. The old units were consolidated onto one laptop which backs up pertinent data to one of the desktops for local redundancy. Net gain: 5.25kWh/day + 8F less heat upstairs

b) I've started using my laptop instead of my desktop for surfing, email and non-gaming entertainment as it uses just 12-16W while my desktop and its supporting equipment suck down 260W. We have also started shutting down the desktops when not in use. Net gain: ~10kWh/day

c) As soon as it warms up enough for things like caulking I'll be re-sealing every window, door. vent, attic access, etc. because heating and cooling takes so much energy. Even without being able to get a reading from the compressor (it's too cold... I couldn't get it to kick on - hehe) and even with the heat being produced by burning natural gas the HVAC system is still our largest electrical expenditure (the ventilation system sucks a ton of juice).

d) Our coffee maker uses more juice on two pots a day than the 32" LCD HDTV that gets turned on for a few hours every evening.

e) My pride and joy which I saved up for years for, the 50" plasma HDTV downstairs, is truly a luxury item. Not only did it cost a pretty penny up front but it is the largest non-infrastructure electricity user. Combined with its supporting equipment (AV receiver, subwoofer, HD-DVR satellite receiver, DVD player, power filter) it takes 600W to watch television, 610 to watch a DVD.

f) Our refrigerator works great, is the first one we've ever had that included an ice maker and filtered water dispenser and came with the home at purchase time, but it turns out it's one of the most inefficient models on the market. It is so inefficient that we'll basically pay for it again in electricity usage before it's retired/recycled.

g) The toaster oven uses the same amount of juice as the microwave.

h) The range light (part of the microwave - it's an under-cabinet mount) is the most inefficient bulb in the house now that everything other than appliances have been converted to CFLs. Despite covering less than 1m of visible space it sucks down 70W of juice. The refrigerator is close behind at 60W on the fridge side and 50W on the freezer side.

i) Thanks to CFLs, despite the microwave only being used for about 10 minutes per day it is sucking down more juice than the entirety of our general lighting in a 24-hour cycle.

j) Space heaters are evil little devices! They use just as much wattage as a hair dryer and some folks run them for 8-10 hours per day. You may as well just donate a percentage of your paycheck to your utility provider.

k) It takes juice to perform surge protection and power filtering. It never occurred to me but it does indeed require power to keep things like conditioning and load protection at the ready. All of the surge protectors in the house, despite being different brands and having different ratings, use about 1W constant while the power filter in our AV setup draws 10W constant.

l) Hair dryers, like all things heating and cooling, are so inefficient that despite being used for just 5 minutes per day it is taking more juice than a 24-hour cycle for our instant hot water recirculator. While my wife's flat iron is more efficient than the blow dryer it still uses more power in just 15 minutes than my laptop does in 4 hours.

m) DeWalt battery chargers use 2W even when there's no battery plugged in and they are showing no indicator lights.

n) Despite being another heating device "heating pads" are pretty doggone efficient. The larger one we have draws just 8W no matter which setting you have it on (it just draws longer to achieve higher temperatures for the higher settings). On this note it really is cheaper to use an electric blanket at night than it is to keep your entire home heated, even if your heat comes from natural gas (I never would have thought this).

o) Shredding paper doesn't take as much energy as I anticipated. I figured it'd be in the neighborhood with vacuum cleaners and blow dryers but ours uses just 77W when shredding 7 pages at once.

p) Glade Plug-Ins only cost about $0.50/year to operate despite running 24 hours a day for that time.

q) The Wii is an impressivley efficient computer! At 18W it uses less juice than my laptop-server. Too bad it's hooked to that 50" plasma and AV receiver.

r) Yes, CFLs (Compact Fluorescent Lights) are that much more efficient than incandescent bulbs. Despite costing over $300 to change out every bulb in and around the house they will pay for themselves in less than 6 months.

s) With rare exception fans are much more efficient than air conditioning. Our meter tall vertical fan uses 31W on medium and while sweeping 90 degrees. You can't even look at a window AC unit for that kind of power, and just the central air's thermostat uses 5W (the central ventilation fan uses 600W - ouch!).

t) Subwoofers designed for the home seem to be much more efficient than the ones made for cars. The last setup I had in a car had a 900W amplifier, but the one that's part of my surround sound system uses just 9W and will rattle every surface in the house if I let it. Maybe all of the ricers should get an inverter instead of an amp...

u) Despite being different brands and being purchased 4 years apart both of our vacuum cleaners pull exactly 1150W.

v) Analog AV equipment requires much less power. Our 15-year-old analog 27" television pulls 50W while our 32" LCD pulls 155, and our analog satellite receiver pulls 9W while the HD one pulls 19.

w) Satellite receivers run at full power even when in "standby" or "sleep" mode. As long as they are locked on to a satellite they are pulling 100% of their juice. This makes me mad... why does my HD-DVR need to pull 52W when I'm dead asleep? However, if you fully turn off the receiver then it will take up to 10 minutes to reacquire the satellite once you power it back up, which is quite inconvenient.

x) The Linksys WRT54G wireless router requires 4W out of the box but only 3W once you re-flash it to run on the Linux firmware, despite the Linux firmware offering 2 extra options over the default one.

y) The Kill-A-Watt is a wonderful, useful, worthwhile device that paid for itself in the first month I got it.

z) As I learned from a fellow that runs the State Legislature's Environmental Protection unit for northern Nevada at Thursday's Green Summit in Reno, if everyone in my area would make the same changes that we have, which required very little investment and no sacrifice, then there would be no talk of building a new coal-burning electricity plant.



With all of the things I learned by reading, researching and measuring I was able to make both physical and mental changes throughout our home and family that have resulted in cutting our daily power usage by more than half (December's average was 43kWh/day while March's was 22kWh/day and I am expecting April's to be around 17kWh/day).

This puts the option of going with a grid-tied solar array within much closer reach as a 3kW system would run about $20k installed (before rebates, etc.) vs. the $38k needed for a 6kW system. I need to wait for warmer weather to see just how much juice the AC compressor draws and then calculate in the cost of converting the hot water and HVAC systems to 100% electricity to get a better idea of exactly how much solar energy we would need, but I'm tempted to wait until I see what my future PHEV will need every day as I'd rather pay off one home improvement loan than two.

 

Thanks for that, Brian.
My wife and I are starting to look at houses. For us, the electrical efficiencies of the house are equally or more important than any other factor. I know that as soon as we move, the first thing I will do is address leaks and drafts before everything is moved in. The second - after moved in and settled - is perform an audit.

Great write-up and tons of useful information. I'm going to print it out as a reminder.

 

Thank you both for the compliments and I'm glad that other folks find this information useful.


Wayne,

lol - I don't know what to call it, either, but I like "hyperwatting".

The LCD monitors pull about 0.5W while asleep and the LCD and plasma televisions use about 0.2W. I'm pretty sure the reason they need some power while "off" is that they are constantly polling for remote control signals and/or ACPI/APIC signals from the desktops, which in turn requires keeping things like input and infrared ports spun up.

The one CRT television that we still have, a 27" model, draws 2W when "off".

 

Great report - I would love to go to some type of renewable energy source, just haven't found a way to make it happen.

I am checking out http://renu.citizenre.com/index.php
Sounds too good to be true, but I'll see if they can back up their claims on the web site.

Cutting back usage is one thing we can all do.

Today the local Baton Rouge area Home Depot's are giving 1 free 14W CFL to each customer, at 11:00 this morning there were still a few left.

 

That's an awesome writeup. I've been thinking of an audit for some time, if for no other reason than just to educate myself about "hyperwatting" .

It's interesting how technology makes going green less associated with "sacrifice" and more with just making informed decisions.

Just finished caulking the shower to fix a leak that was corroding the baseboards/sheetrock right next to it. It's a shame that energy leaks can't display some kind of similar visual unpleasantness.

We have CFLs in bulk and are using them when conventionals burn out. Up to around 15% of the house so far. Hopefully we'll be 100% CFL by the time we sell the house in a couple of years.

 

Great writeup Brian! There's a bunch of things there I never would have thought of. Right now I'm replacing incandescents with CFLs as they burn out, and I use my laptop about 90% of the time instead of my desktop, but its just peanuts compared to your house-wide audit. Bookmarked for when I get ambitious.

 

Wayne,

That's a great idea, thank you for the compliment, and I'm more than glad to be helping everyone with this.

On a side note, the 2 documents linked in the original post have been updated to reflect some readings on some of the 240V devices (I was able to use a multimeter for some things) and a few smaller, missed appliances.

The inventory is now as complete as I know how to make it, and the only electrical device I am aware of that is missing is the a/c compressor. I assume it's the worst culprit of them all and I'm hoping to be able to extrapolate its energy usage once warmer weather is here and it is in use.

 

Great writeup, Brian! Thanks for taking the time to put it on paper and sharing it.

A question: You've made references to energy used by devices that have no AC plugin (e.g., range light, HVAC). Since the Kill-a-Watt is designed for plugin devices, how are you measuring the others?

 

You're welcome, Jim.

Our range top setup has the microwave mounted directly above it and contains the range light and exhaust fan on its underside. This way I was able to get readings for all 3 devices (microwave, range light, fan) through one plug. I bet most homes in the U.S. have a cord plugging in somewhere right above the range light/fan. Just grab a step ladder and start rooting through the cabinets.

Our central air ventilation system has a 120V wall plug as well. It even has its own outlet for it.

The dishwasher plugs in under the kitchen sink and shares an outlet with the garbage disposal.

The dryer was a bit trickier, being 240V (the Kill-A-Watt is only rated for 120V). I used a combination of multimeters from my own collection and my neighbor's to very uncomfortably hang over the back of the dryer and pull its plug out from the wall far enough to get the leads onto the prongs and then stay like that for a while (yes, I'm still sore - hehe).

 

What a great analysis this is, and a big thanks from me also. Data like this gives me so much inspiration. A question -- have you added up this cost per year for everything and compared it with your actual annual electricity cost? Is it fairly close?

This is where a timer might work wonders. Turn off the receiver at say midnight, and start it up again at noon would save 50%. It might even work for weekends too.

 

OK, I just assumed these devices were hard-wired. There I go assuming again!

And I've assumed the same about some of the same devices in my (or more accurately, my fiancee's) house. You've inspired me to check it out further. I've thought about the Kill-a-Watt, but have held off because I figured that many of the hungriest energy eaters are hard-wired.

Can I assume (there I go again!) overhead lights were calculated based on bulb wattage and duration of use?

 

We've only lived in the home since mid-October last year so I will fine-tune it as we go, especially the estimated running time of the central heat and a/c. So far it's pretty doggone close, though.

I hadn't even thought of that for this application... thank you! I'll pick one of those up tonight and experiment with it.

That's exactly how I did it. It's rare - especially in modern homes - for a lighting fixture to pull more wattage than the bulb requires, so once you know your bulb wattages and make the effort to track light usage you can easily calculate a kWh/day rating for your general and specific lighting.

This effort will have the added effects of making you immediately want to:

1) Change every bulb out to a CFL regardless of whether or not the incandescent you have still work. Incandescent bulbs are another thing that just wastes wattage like you would not believe... not only do they require 4x the energy of a CFL to produce the same amount of light but they also put off a lot of heat which causes your central cooling to work harder, or can even create "hot spots" in the home that lead you to run the central air systems harder to compensate in that spot. This means it's not worth keeping them until they burn out just for the sake of trying to maximize their usage, and they'll start to bug you anyway when you realize that every time you flip the switch on one of your remaining incandescents it's costing 4x more than it has to. hehe

2) Turn off the lights when not in use - religiously.


Our incandescent lighting was costing us $20-$30 more per month than it had to, not including the short lifespan of most incandescent bulbs. $20 buys 6 or 7 CFLs. Those CFLs will only take on average 3-4 months to pay for themselves, so changing out even the bulbs that are less frequently used (i.e. guest rooms) will be paid for in just a few months by the savings of the lights that you use more frequently.

Now that we've begun to pay close attention to our lighting use we've managed to shave another $6/month off the bill, even with the CFLs in place (if we were still using incandescents the impact would be 4x greater).

Aside from the monetary savings the total reductions we have made so far represent a real-world drop of 1,500kWh/month or 1.8mWh/year that our electricity provider does not have to produce. If everyone in my city of 200,000 and region of 400,000 did the same there would be no talk of building a coal burning plant.



Wayne,

I'm curious... What would be the reality - both good and bad - at your plant if, over the course of 1 year, every one of your end-point customers dropped their electricity usage by 50%?

 

You know it's tempting when you look at this data to do like Ms. Irony and say "well I can afford that". Especially the low numbers on pg 2. But everybody's got some low-hanging fruit -- stuff that could make a big difference at little sacrifice. This is a great map to it.

 

If my wife see's this. My fish tanks, computers, TV's, Audio Eq. will be gone.

 

There is a good kill-a-watt story in today's NYTimes. May need to register to see it though.

http://www.nytimes.com/2007/06/14/t...em&ex=1181966400&en=3e1939192b5f2028&ei=5087

 

I'm very happy to see that this site will allow discussion about home energy use. I started with the house before I got to the cars. It was the biggest offender. Net results were a 50% drop in KWH used. Our house is totally electric and as such was a good candidate for improvements. We now average 44 KWH a day instead of 88 KWH.

As you would expect, the most expensive items were the biggest inprovements. However, the house is so much more comfortable that before. If anyone is interested I can give you a run down of what I did.

Louis B