Spend any time researching the current field of home energy monitoring products and you’re very likely to see mention of the Kill-A-Watt, a device from P3 International. The Kill-A-Watt can read the energy use of an appliance plugged into it, and is marketed as a tool for identifying the energy vampires that might be lurking in our stuff. It’s rightly mentioned as a useful tool in the absence of the smart metering dashboards of our future.

I can attest to the Kill-a-Watt’s usefulness, but I also found it kludgy, difficult, and uninspired. Yet, it’s the only product of its kind on the market in the United States. While I am glad that it’s available, I think that some basic usability problems with the device would have been avoided with a little user testing.

(I have heard that there are many such devices on the market in Europe and elsewhere, and would be interested in hearing if the others’ product designs — or lack thereof — are comparable.)

Button overkill

The Kill-A-Watt seems to give you a lot of power, what with all its buttons, one for each unit of measurement — but really, do I need to know the Volts, Amps, Hz, or VA of my Ikea lamp?* Actually, I only want to know about Watts, since that is the energy language I speak, as a home user. I’m not drawing up schematics or breaking out the soldering board. The device hasn’t yet outgrown its roots on the electrical engineering geek’s workbench.

This device doesn’t need any buttons. Let me connect a device to it, and make a Wattage reading: and I’m done. If the maker wants to make several units of measurement available, one button would suffice to make the setting, and the default should be Watts.

Those hard to reach places

Basic assumptions in the form factor design of the Kill-A-Watt present problems for me once I start to test appliances around the house. It plugs directly into a wall, and its LCD display is on the front face, so to make any readings I need to crouch down on the floor. That’s even more than a little annoying if I want to test the stuff that’s plugged in behind the couch.

One potential solution would be to place the display on the top of the device, so that I can make a reading from above. Even then, the display might still be hard to read if it’s in a cramped space, since it lacks a backlight. My solution is to plug the Kill-A-Watt into an extension cord, so that I can use the Kill-A-Watt like a handheld device. That way, I can make readings where it would otherwise be hard to read, and also test appliances plugged into outlets that simply won’t fit the Kill-a-Watt.

The Kill-A-Watt is only easy to use if you plug it in to an outlet at eye-level (preferably a workbench), and bring your stuff to it. Most of us, I’d wager, just want to test our appliances where they are.

Testing over time

You can also leave an appliance plugged in to the Kill-A-Watt for a length of time and make a reading of its accumulated kWh usage. This is certainly useful, since the energy many appliances pull oscillates or varies with types of use. My laptop computer, for example, might use 25 watts using a word processor, but 70 watts running a game.

This kind of measurement also hints at the kinds of calibration the Kill-a-Watt enables you to do. When I first tested a bunch of my home appliances, I jotted down the initial Watt reading for each and moved to the next. That helped me identify those weird vampires I didn’t expect* — on this first pass I removed over 100 Watts of continuous energy suck from my tiny apartment. (Chief among my strategies: power strips and just uplugging stuff when I’m not using them) Later, I took more time and measured my commonly used things over a period of a few days, to get a better look.

A transition device

The Kill-a-watt represents the kind of cheap and simple interface we need immediately, as it may be years before the average home is equipped with smarter metering and ambient feedback devices. The market has yet to be really explored, as far as I can tell. I think even small improvements in its usability, and a modest, incremental extension of its functions (perhaps adding easy upload of your appliance data to a computer via USB) would bring us a little closer to more efficient use of home energy.

* I found that my Ikea lamps, by way of poorly designed power adapters that apparently like to stay warm for no reason, pulled 6 watts on average when turned OFF.