Conservation tip: Measure your energy use


Real time feedback in a car can change your driving patterns. What about your house?

Many users of Prius’ and other hybrids report that simply having the fuel efficiency counter on the dash has changed their driving behavior. What used to be a “get there as soon as possible” task is now turned into a “get there with the highest MPG” task. Pretty cool.

The same promise has been around for decades in energy, generally referred to as “smart metering“. Instead of the useless twirly-whirl sitting behind the bushes outside, energy experts envision placing a real time meter in the kitchen that shows real time cost data. One day it may even display differential pricing, encouraging you run the dishwasher while you sleep, instead of in the middle of the day. There’s a nifty case study on the Bayard/Ampy website if you want to learn more.

kill a watt

Inexpensive consumer tools can let you play the role of energy detective around your house

But, let’s face it. Your utility moves at the pace of molasses in Mongolia. You don’t have one of these fancy meters and you want one. Well, there are now quite a few solutions, such as the Killawatt, available for under $30 that will help you measure energy consumption. They’re not perfect, but they will get you most of the way there.

I’m testing one of these and hope to report back in a few weeks with my experiences. Any TerraPass members have one and care to share?

There’s an old business cliche: you can’t manage it if you don’t measure it. Now if you’ll excuse me, I’m off to measure that VCR that never gets used…

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  1. Anonymous - March 7, 2007

    I never knew there was such a product available. I am eagerly awaiting for your report on how it does.

  2. David - March 7, 2007

    I have a Kill-A-Watt device. I now uplug my laptop powere adapter. Shocking how much energy it uses even with no laptop plugged into it. I also uplug all our cell phone chargers when not in use. They too use a lot of power even with no phone attached. Great little device but only measures one device at a time. I would love a whole house meter in the house.

  3. Rick - March 7, 2007

    I can personally attest to the effects of having a real time meter on your energy consumption. I drive a Civic Hybrid, and just having the real time MPG meter has had a big impact on my driving. I now make it a game every time I drive somewhere to see how high I can get the mileage (while being safe of course). Now instead of driving 75 mph to get somewhere on the freeway, I just relax in the slow lane and drive 55-60 mph. I can now regularly get 50 MPG round trip as long as traffic doesn’t come to a stand still.
    In fact, I have actually said to people before that I think there should be a law requiring every vehicle sold in the U.S. to have a real time MPG meter! This simple idea would probably save hundred of thousands of barrels of oil and reduce a significant amount of pollution. People are just less likely to take off at a green light when they see the MPG meter dip down to 8 MPGs. We’d probably see a reduction in accidents too.

  4. Anonymous - March 7, 2007

    The article on measuring states:
    “What about my wood stove?
    Technically, the burning of wood is carbon neutral. Of course there are many other downsides to it, and we’re not recommending it as a substitute for gas or other more traditional energy sources.”
    Technically, coal is also plant sequestered atmospheric carbon, so it is also “carbon neutral”. The main downside to burning wood is that it pumps CO2 into the atmosphere and adds to global warming because our human population and burning of evrything is way beyond sustainable.

  5. tom - March 7, 2007

    Coal is not carbon neutral. It is in fact the enemy of the human race (not my quote).
    Coal = prehistoric carbon, not part of current carbon cycle
    Wood = current carbon cycle.

  6. Chad - March 7, 2007

    Driving slowly to save gasoline is a waste of time and resources in most situations. Roughly, you are saving about four times the price of a gallon of gas per hour, or about $10/h. Unless you are a minimum-wage worker driving by yourself, the odds are that your time is more valuable than this.
    Please drive 75 mph, work a couple of extra hours a week with the time you saved, and send the money to Terrapass. You will offset many times the carbon with the same effort, while avoiding pissing everyone off who DOES have somewhere to be.

  7. FD - March 7, 2007

    I was recently visiting a family member in the rural midwest. The home is mostly electric with propane suplement for heating when electric is less availible. The electricity is supplied by a co-op and he has a neat system. The co-op can shut down certain circuts in his home remotely when they are at a peak, so hot water, baseboard heaters, etc. can be made in active to level load for the utility. Plus he gets a great rate on his electricity for his “sacrifice”. The system has a nice meter that displays current usage, circuts being limited etc. I wish big utilities would offer this as well, it allows them to run more efficiently and me to save money, sounds like a win-win. And yes the meter does curb his usage by keeping it in your mind, just as the mpg meter does in my 97 saab, which is getting a combined mpg of 31 despite what the doe says it should get.

  8. Scott - March 7, 2007

    The Kill-a-Watt works very well. I currently own two of them. One of the major uses of the product is to evaluate standby electricity consumption. For example, my RCN DVR use 30 watts of electricity 24/7. My computer speakers use 6 watts when not in use. Kill-a-watt gives me the incentive to disconnect these items when not in use.

    In this month’s Popular Science magazine, a new product that has a wireless sensor attached to your home’s power meter was profiled. It is called Powercost Monitor and can be found at . This provides whole-house power consumption monitoring.

  9. S Page - March 7, 2007

    I have solar PV panels and hence a net energy meter that very clearly shows both total kilowatt-hours consumed and instantaneous power received or delivered.

    However, it and my Kill-A-Watt are little help figuring out what’s unexpectedly wasting electricity. It would be great if each circuit in your home’s electric distribution panel displayed its power and energy consumption, so you don’t have to disconnect each in turn while someone else stands outside by the meter.

    Congress should require average and standby energy consumption and relative energy consumption (like Energy Star for appliances) in all product information and ads. And MPG meter in all cars as the default display.

  10. Monty - March 7, 2007

    Quick Note to Chad:
    Driving 75mph is far worse for gas mileage than driving 60mph. The ideal in gas mileage is the slowest you can drive in the top gear, of course, which is actually less than 60, of course. That said, friction from the air makes driving above 60 a very poor idea as it relates to mileage.
    As for having a meter to measure energy use in your home, it is one of those lovely ideas but not currently possible. I have Kill A Watt, and it is a nice idea for measuring a single item at a time, but it is a safe bet that any product in your home that converts AC current to DC current (all home electronics — VCR, DVD, TV, computer, phone adapters, clock radio, audio equipment, baby monitors, microwave oven, cable TV boxes, etc) is using electricity by just being plugged in. You do not need Kill A Watt to tell you that.
    While unplugging all of these devices is a fantastic way to save electricity (and we do that in our house), it is also a tremendous hassle. For example, we unplug our DirecTV box when not in use, but that means when we want to watch TV it takes us 3 minutes before we are actually watching a program as we wait for the sucker to reboot. We are saving the environment, certainly, but the hassle involved in unplugging equipment means it is an annoyance many of our family members refuse to do.
    What would be ideal is for electronic manufacturers to have a true power-off switch that stops the device from using any (or very little) electricity when not in use. Only then will this problem be solved, I am afraid.

  11. John E - March 7, 2007

    There also is a very innovative new product that has won many awards that can monitor power usage for the entire house in real-time. It is distributed in the US by Cenergies Unlimited.

    You can learn more here

    Basically, you attach the sensor clips to the phase wires in your fuse box and monitor your usage with the wireless LCD panel.

  12. Anonymous - March 8, 2007

    To “Chad”:
    Quote: “Driving slowly to save gasoline is a waste of time and resources in most situations. Roughly, you are saving about four times the price of a gallon of gas per hour, or about $10/h. Unless you are a minimum-wage worker driving by yourself, the odds are that your time is more valuable than this.

    “Please drive 75 mph, work a couple of extra hours a week with the time you saved, and send the money to Terrapass.”

    What a ridiculous comment. Basically, “use more energy, and buy an offset” — it’s comments like this that give people fodder to complain that carbon offsets are pointless. People who drive 75mph should all be arrested and jailed — it would make the roads a lot safer and more pleasant for those of us who obey the speed limits, and try to actually reduce our consumption, instead of just paying lip service.

  13. Anonymous - March 11, 2007

    I bought the Kill-A-Watt and have been measuring things in my home. I thought that I’d share my observations on my TiVo. I have a DirecTV TiVo R10, upgraded with a 250 GB Maxtor quickview hard drive. I also have a UPS connected.

    TiVo and UPS: 28 watts
    TiVo (standby) and UPS: 27 watts

    Not much of a difference for standby mode. The TiVo mostly stays on during standby mode: the CPU and fan stay on, and the hard drive keeps spinning. However, while in standby, the LEDs on the front go out, video signals aren’t sent out, and it doesn’t automatically maintain its 30 minute buffers of the active channels. That is, it doesn’t read/write from the hard drive, even though the hard drive keeps spinning.

    The reason to keep the hard drive spinning is that it avoids the stress of starting/stopping, increasing the life of the drive. Some say that avoiding disk read/writes during standby would also increase the life of the drive… I’m not sure about that, but it seems plausible.

    Anyway, there’s a slight advantage to putting TiVo into standby mode, both in terms electricity savings and possibly increased life of the hard drive. However, I wish that they had done a better job in reducing power consumption during standby mode so that it would save more than one watt.

  14. Gregory - March 14, 2007

    These are all pretty good comments. I have a quick observation. I drive an ’06 Hybrid Civic and I love being able to watch the gas mileage on my dash. I always wondered if they could make a “Cruise Control” that keeps mileage constant instead of speed. It’d be just for fun… obviously you can’t slow down too much in certain scenarios, but it’s gotta be possible, right?

  15. Greg - March 14, 2007

    Oh yeah. One question. I know that unplugging your car charges and laptop charges saves a lot of electricity. But what if you plug them into a power strip and then turn the power strip off? Would that save the same amount of electricity or do you have to physically unplug the devices?

  16. Adam Stein - March 14, 2007

    Hi Greg —
    In answer to your first question, having your car automatically speed up and slow down sounds like a lawsuit magnet.
    In answer to your second question, power strips work great.

  17. Bob March - December 11, 2007

    It appears I’m posting much later in the thread, but I have to say that I’m really pleased with the Power Cost Monitor device NSTAR gave me. I’ve been using it for a couple months now and compared to last fall, I’ve saved about 12-15% on my bill. It cost only $29 and already it paid for itself. It shows what the whole household is using and you can monitor individual appliances as well.

  18. Anonymous - March 29, 2008

    Please, help us answer this question. Which uses more power, a t.v. or an electric light bulb. I say t.v uses more, hubby says light bulb uses more, who gets the ‘wet noodle’? Sherry

  19. Gustav - June 22, 2008

    Measuring power does make a difference in how some people behave. Turn off unused lights, set the thermostat in your house, or how you drive. Another method would be to shop green when making new purchases.
    For example, large flat panel TVs use a greater amount of energy than the older CRTs. I started thinking about this when I was in Walmart standing near their wall display of flat panel TVs. I felt warm. I put my hand next to one of the screens and realized the heat was coming from the sets themselves. Collectively they warmed the entire area. Heat given off means energy released.
    I researched the sets by going to their websites and reading their spec sheets. One 50 inch Plasma set was rated at 520 Watts. The LCD screens were rated lower and the smaller the set the lower the Wattage. My 1990 Sanyo 27 inch is rated at 87 Watts per its decal. I’ll get the actual when I receive my KillAWatt.
    What I’m getting at is that if a person does a little research up front, you can make better choices in your purchasing. I still would want a TV the size of the wall. But I also don’t want it to become a radiator.

  20. eunice kim - February 25, 2009

    Dear David,
    I am student from Rhode Island School of Design. I am currently working on a project with MIT student to development energy managing device through Measure-Communicate-Motivate-Control strategy.
    Can I have an interview with you?
    my email is
    Thank you

  21. eunice kim - February 25, 2009

    Dear Scott,
    I am student from Rhode Island School of Design. I am currently working on a project with MIT student to development energy managing device
    through Measure-Communicate-Motivate-Control strategy.
    Can I have an interview with you?
    My email is
    Thank you