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This page is too big ... get started by measuring your idle loads and seeing what fraction of your consumption they are.


How to make your home more efficient

Get a copy of Consumer Guide to Home Energy Savings. Flex Your Power has a DIY Home Energy Audit as does LBL and companies from ReNu and Sustainable Spaces to Sears offer energy services. Insulate and Weatherize: Expert Advice from Start to Finish may also be helpful.



How to Collect Data with a Watt Meter


Having flipped through The Home Energy Diet, I suspect the following is similar, but I've deliberately written this before reading it. I encourage people to buy the book if they want to know more. It contains a wealth of background material as well as excellent instructions and many relevant examples.




Electricity consumption is usually measured in watts. Watts tells you how much power is being drawn right now. Total electrical energy, over time, is measured in watt-hours, since 100W for a minute is less energy than 100W for an hour. The amount of power times the amount of time is the amount of energy. So if a radio draws 5W for 2 hours, it has consumed 10 watt-hours (Wh). And if a light has consumed 100W for 10 hours, that is 1000 Wh or 1 kWh, which is what you will see on your bill.


Calculating Savings has some more information (e.g. a kWh cost roughly 10 cents in the U.S.).


For geeks: power is energy per time unit. So when you multiple power times time, you get energy. And, if you were wondering, a watt is a joule/second ... so a watt-hour is multiplying by time to remove the time component putting us back with energy, in standard joules if we cared to convert it. But before you wish the electric company billed in joules, think about how much more challenging it would be to have them give us average power draw (in watts): e.g. one house averaged 500W for the whole month.


Watt Meter Overview / QuickStart

Collecting watt meter data with a stand-alone pass-through meter is easy. Your meter should have at least two basic modes. The "watts" mode displays the current instantaneous wattage (not to be confused with VA) being consumed by whatever is plugged into the meter. The kilowatt-hours (kWh) mode multiplies the instantaneious wattage by however long it has been being consumed. That gives a total amount of electricity consumed since some point in the past (usually whenever the watt meter was plugged in).


For those in Wisconsin without a watt meter, supposedly libraries are getting them! From an FAQ:


Q: Why is my electric bill so high?

A: If your electric bill seems high, it may be that you have one or more electrical appliances that need to be replaced. You can check out a watt meter (or portable energy meter) from your local library. With a watt meter, you can measure the amount of electricity that an appliance (for example, your refrigerator) is using. If your library does not have a watt meter at that location, they can get one through an inter-library loan.


You have to tracking total energy consumption (kWh) for devices like fridges which cycle on and off (100W times 10 minutes; then 0W times 20 minutes, etc). After leaving it plugged in for a day or so, you divide the number of watt-hours by the number of hours to get average wattage that you can multiply by longer period of time (like a month of a year) to see how much the device consumes over that amount of time. The Kill-a-Watt and Watts-Up also have a timer which makes it easy to calculate the average wattage (divide the watt-hours by the number of hours to get average watts! :).


Start with a piece of paper

Start with a sheet of paper (or Spreadsheet, but really, scratch paper is easier) like this:

Device "off"/standby in-use idle sleep max daily use daily energy Notes
Apple MacBook Pro 15" 0W (charged) 46W downloading 23W (Finder) 6W asleep (no USB devices) 50W compiling 2 hours ~70 Wh need to try a game, what's with 6W asleep?


See our Data page for more ideas on what you might want to collect. Use the Notes column to record any suspicions you have. If you know what you want to collect, go for it. Please consider entering your data not only so that others can learn from it, but so that you yourself can refer to it in the future.


If you want hints on where to start, continue down this page.


Make a list

If you want to collect data on everything, go room by room and check every plug and switch (ceiling light bulbs generally consume the number of watts the bulbs imply). Don't forget to at least take note of things like pumps, doorbell circuits, and electric stoves/dryers which may have "hardwired" connections into your circuits or be too powerful to use with a basic watt meter. There are other ways to collect data for these devices which we will discuss in detail at some point in the future.


If you don't want to go room by room, here's a list of devices we've discovered consume unexpected amounts of power

  • anything you leave on all the time(!): internet, accent lighting
  • anything with a remote control: televisions, stereos, boomboxes
  • anything with "soft power" (no "real" on/off switch): computers, computer accessories, sub-woofer, cordless phone
  • anything with a clock: microwave, stove, VCR, bedside radio
  • anything with a "power brick" (check for warmth; investigate Replacing Transformers or upgrading to EnergyStar)
  • ?


If you just want to see big numbers and to be reminded about things that consume a lot of power

  • anything that produces heat: space heater, coffee machine, toaster, iron, hair dryer
  • anything with a big motor: fans, pumps, vacuum cleaner, furnace/boiler


Heating appliances where society has a choice (Natural Gas Heat is more overall efficient & generally cheaper)

  • range/oven/stove (how efficient is a gas pot or frying pan over a gas flame?)
  • dryer: you may want to hang-dry your clothes; if buying a new washer, a front-loader with a high-speed spin saves on drying
  • hot water heater: low-flow showerheads, aerators, washing with cold water, and efficient washers really help



Go to it. Enlist your friends and family. If you are really ambitious, you can cut power to your whole house and go circuit by circuit to figure out where it is all going. But if you start with your list from above, you'll quickly have most of the data you need. Just don't forget to write it down!


Don't worry too much about absolute accuracy this first time around. For example, Apple will tell you that their power supply is drawing more than 0W, but the goal here is to see what the meter says is being consumed and to get a big picture of the electrical energy consumption within the home. Use the notes column to record any discrepancies you suspect. EC users are always interested in solving mysteries.


Compare to your bill

Look at how much each device consumed and how long you tend to use each device each day. Multiply the watts by hours and divide by 1000 for kWh. Now find your last couple of electric bills. If they sport a kWh/day average, compare directly to the total of "daily energy" above. Otherwise, multiply by the number of "billing days" covered by your bill and compare the number of kWh you were changed for with the number of kWh you were able to identify using your watt meter. If you were able to positively identify 50% or more of your electricity consumption, congratulations!


Note that consumption varies with season, number of people living in the home, etc. If you are trying to size a solar array, etc, you'll probably want to survey two years worth of bills. And if you've been making significant changes, you'll want to compare to previous similar seasons. Your local utility may have information about the weather in past months (PG&E calls it "degree days" for both heating and cooling).


See also: Calculating Savings, Utility Bills


Consider Action

Take the data you have so far. What are the biggest consumers of energy? How many "little" consumers are there and how do they add up (especially 24x365)? Is there anything in particular you think could be done better? What's the easiest most fun change you could make? Which would be the most challenging? Are there behavioral changes that would have a positive impact on both your life and your energy consumption?


If you're motivated to make changes, consider how much time, effort, and money each one might take and how much energy you will save. Some people like a technical challenge, but most want to start with the biggest steps that will fit within their budgets. First off sealing and insulation pay off, big time. After that, maximizing the efficiency of regularly-used devices (from CFLs to refrigerators). Then reducing your large, periodic loads and last, but certainly not least, eliminating "phantom" loads.


Sealing, insulation, and programmable thermostats that you set to your schedule really help. Even better are occupancy sensors and per-room thermal zones that let you really only use energy when you need it. Energy Star appliances are well-known ways to save and the watt meter data you've collected will help you prioritize any appliance replacements.


The watt meter data should also make it clear which loads consume due to their frequency. For example, getting a pool cover so you can run the pool pump/filter/heater(?!) less is going to pay off a lot more than trying to vacuum less (unless you vacuum many hours a week). At the other end of the spectrum, your microwave's idle power supply probably consumes more energy for all those hours the clock is on (and the buttons ready to push) than it does in those few minutes heating food each day (10 kW-minutes vs. 1.440 k-minutes x N idle watts).


Some unique ideas:

  • put things on power strips you can easily turn off
  • put a lamp cord switch into the cord for an appliance that never shuts off (e.g. a boombox; batteries can preserve settings)
  • install a mechanical timer on your bathroom fan so you don't leave it running
  • install a time of day thermostat on your water heater
  • install a mechanical timer on a strip attached to your microwave
  • use X-10 controllers to turn (e.g. networking) equipment on only when you need it
  • RMI's Home Energy Briefs
  • if you have a lot of "wall warts" (AC/DC transformers), replace them with Energy Star models (now sold by Radio Shack)



Extra Credit: Compare idle consumption to your outdoor meter

Let's say you think you have a pretty good idea of where you electricity is going. You've used some averages for some of the big items and are pretty confident you know where the energy is going. You've even implemented a few changes and are happy to be seeing some results. You're ready for a something more challenging than websurfing for ec.org.


Turn everything you'd normally leave off, off, as if everyone was out of the house (a day when everyone else is out restoring native plant habitat is good). Go outside and watch your meter spin. Take a stopwatch with you. Time it. Go back inside and make sure nothing unexpected is running. Meter the fridge and wait until it's recently finished / isn't defrosting itself (1000+W :P). Or unplug it with a note that says "don't open; local energy consumption scientist at work!" Make sure any well or pool pumps are aren't going to kick in.


Calculate how many watts your home is consuming based on the spin speed and whatever factor you've previously calculated (# watt-hours/rotation). How close is it to what you think your idle draw should be. What's still on? Does it need to be? Is there a way you could eliminate it?


David B covers reading your house's meter in phase I of his 4 Phases ... powering your house when it is "off." :)


EnergyConsumption aims to help you both figure out what you want to know and make any changes you are interested in making. Go forth informed and challenged by the opportunity to optimize, be comfortable, and to have fun!




Random Instructions


Random Tips






(warning: ramblings on the philosophy of our direction-giving beyond this point)

EnergyConsumption (purpose/background)


So the thousand and one or the hundred and one ... some have case studies, but I don't think any of them have people posting their utility bills before and after putting themselves or their home on an energy diet. I think EnergyConsumption has the potential to innovate in this area as well as to provide various "diets" (i.e. sets of bossy instructions that tell you what *to* try, not just what to cut back on). We're going to need to look at the existing good work to make our sets of "do this" instructions unique.


For example, I'd expect every energy utility to have a region-appropriate page of generalities on how to save there. We want to help people and businesses go further, to question (but not feel worse about) every watt, therm, BTU, and drop of water, and figure out how to optimize. I expect businesses to grow out of EC as experts begin hiring themselves out to apply these ideas.


Below are a bunch of things off the top of my head. Such "diet" directions get into the realm of environmental impact and value judgements. I want to be appropriately bossy to people who have said, "yes, I really want to save energy!" and not assume that they meant "yes, I really want to save energy and want to hear why I must give up meat, my car, my house in the suburbs, and my yearly vacation to Mexico." I don't like telling people I don't know that they can or must change their lifestyles. However, I do want to empower them to do so within the technical, measurable realms of energy consumption.


I'm not yet sure where we're going to draw the line for EC proper: I certainly encourage each user to make their own custom "energy diet," but I don't want EC to be about regurgitating all the high-level changes one can make, along with the implicit selfrighteousness. We need to keep it to hard numbers, or something. We want save the world type sites to link to us for whatever we're really good at. Maybe we could say "consider eating less meat" after our users have visited farms and calculated the energy that goes into the various forms of meat in their supermarkets.


(need to link to some of the many web sites listing these things this ... e.g. http://green.yahoo.com where you can make yourself a list)

for the home

  1. get CFLs (make lighting 5% of your bill instead of 20%)
  2. use task lighting
  3. stop the Junk Mail
  4. insulate!
  5. if making changes, consider motion / occupancy sensors


for travel

  • optimize beyond driving alone to work
  • look for fun times to walk or bike (realize the awesomeness)
  • build not driving into your family routine
  • take the train or a boat instead


for the computer geek

  • let the computers and monitotors go to sleep
  • use WOMP


for your diet

  • find food that is produced nearby
  • eat less meat




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