blog

Energy Monitoring Tools

Now that you are a pro at tracking your monthly utility usage, it's time to drill down and start looking at how you use energy by the week, day and even hour.  In order to learn what appliances and household items are the biggest draw in your energy footprint, you need feedback on how these devices are performing and when they are in use.  In order to do this, you need an energy monitor in your home.  In this article, I will cover three types of energy monitors: plug-in device monitors, "moment of use" monitors and Internet-enabled, data logging devices.

Plug-in Device Monitors

Kill-a-watt Device Monitor

A device monitor is used by plugging the monitor into a 120v household outlet (therefore US only) and plugging the device to be monitored into the outlet socket on the monitor.  This allows the homeowner to monitor several metrics: voltage supplied to the device, watts "drawn" by the device and energy use over time (watt-hours or kilowatt-hours)  The most popular of these monitors is the Kill-A-Watt.  If you want to know how much energy a table lamp uses, unplug the lamp, plug in the Kill-A-Watt and plug the lamp into the monitor.  There are several buttons that let you choose between the options listed above.  The most popular choice is to test to see how many watts are drawn by the device.  If it draws somewhere around 60 watts, then you probably have a 60 watt bulb in your lamp. As a test, turn off the lamp, change the bulb to a different watt bulb, turn it back on and see if the watt value changes.  Another good test for the Kill-A-Watt is to turn off a device plugged into it and see how many watts are drawn when the device is off.  This will help you calculate "vampire loads" in your home.  Vampire loads are energy used by devices when they are supposed to be turned off.  See our post on vampire loads.

You can also push the button for kilowatt-hours and see how much energy a device uses over time.  the Kill-A-Watt doesn't keep track of time so you will have to do that yourself.  Also, if you unplug the KAW it loses the data it stored for the device.

One of the bigger drawbacks to the Plug-in device monitors is that they will only work with devices that plug in to a household outlet.  They also only work with one device at a time.  There are other options for getting a bigger picture of your energy usage in your home.

Moment of Use Monitors
The next level of realtime energy monitors are devices that monitor the total electricity usage in your home.  I call these "moment of use" monitors since they give you a picture of your total electricity usage for the current moment in time.  This is a great way to get instant feedback on behaviors in your home.  Typically, these devices include a device that attaches to your electricity meter and a display unit that communicates with the meter-mounted device via a wireless signal similar to a cordless telephone.  The device I used is called the PowerCost Monitor by Blueline Innovations.  Blueline is located in Canada and also supplies their monitor under private label to Black and Decker. (at least it appears that this is the case since their device looks exactly the same)

When I used this monitor in my home, I was able to place the display unit on my bedside table.  I found this to be a very effective way to use this device since I was able to monitor closely the fluctuation in energy usage while other family members were moving through the house and using different devices.  For example, I noticed that a few minutes after one of my children started showering, the display unit jumped from its 3-400 watt idle value to over 1.5 kilowatts.  After a little thought, I realized that was from the hot water heater turning on.  When I hear the AC relay flip and the house begins to cool off, I watch the display unit jump to over 3kw.  I found this type of monitor to be an effective way to begin understanding the systems in my home and how different behaviors affect how much energy we use.  The PowerCost Monitor can also track electricity usage by dollar cost if you enter in the electricity rate in your area.  I found that this wasn't as an effective tool for me since I was more interested in units of electricity than cents per watt used.  See our post on the PowerCost monitor for more information.

Moment of use monitor

After a few months of monitoring, the "moment of use" monitor outlived its usefulness and I was ready for a more sophisticated tool that could help me look at my usage over periods of time so I could track trends or look for patterns in how I use energy through the course of a day or week.  I knew this would require a monitor with data-logging capability as well as internet access.

Internet-enabled Data Logging Monitors
In the past few months, several internet-enabled energy monitors have arrived on the market.  In addition to giving you access to monitoring over the internet, they also provide data logging so you can look at usage trends instead of just "moment of use" data.  An example of trending is, "how much energy do I use on a weekday vs. on the weekend?" or "Do I use more energy in the morning, day or evening?"  By providing answers to these questions, a homeowner is empowered with the knowledge of understanding how they use energy.  With this knowledge they can begin to make educated decisions on the most effective ways to reduce their energy usage without making major changes to their behavior.

The TED 5000 from The Energy Detective made by Energy, Inc. in Charleston, SC is the most popular and full-featured IP-Data Energy monitor on the market.  I purchased a unit several months ago and you can read more about it here.  Once I finished installing the unit in my breaker panels, I plugged in the gateway and began logging my energy usage right away.  In addition to the online dashboard, TED also has an optional display unit that displays energy usage wirelessly for viewing in your home.  I chose not to get the display unit since I was more interested in remote monitoring via the internet.

After configuring the gateway, I set up TED's most powerful feature: Google PowerMeter integration.  Google offers integration with the TED5000 with it's Google online metering software.  The TED communicates with the PowerMeter every 15 minutes and provides electricity usage data that is stored and graphed in Google PowerMeter.  Google provides a widget that is displayed in your iGoogle portal page so you can monitor your energy usage from any device in the world with internet and a browser. (including an iPhone)

TED also offers an API that allows third party tools to pull data from the device in XML format.  This works very well and I quickly built a web application that wakes up every morning and tweets my electricity usage from the previous day to Twitter.  Now that I have my TED and Twitter talking, I now have a great understanding of how many kWh I use per day and can drill down in Google PowerMeter to find out when and where I'm using electricity during the day, week, month and year.  I haven't been using the unit long enough to look at monthly usage compared to my electricity bill but expect to build a tool that compares these two sources of data soon.

The Future: My Wish List
My thirst for energy knowledge has not been quenched with the TED5000.  This tool has empowered me to want to answer some new questions: "How much energy does my AC use compared to my washer, dryer, hot water heater, refrigerator, etc."  "How much energy does it take to charge my electric car and how many miles can I go on that charge?"   To answer these types of questions, I need to be able to monitor individual systems in my home.   If I can isolate key systems by circuit breaker, I would like to have a "smart" circuit panel that has current transformers built into the circuit breakers that register unique data by circuit.  Having "smart: appliances that report energy usage data back to a "smart" monitor in addition to data by circuit and total home energy consumption would give me deep insight into the energy usage in the home.  This deep insight would give me the knowledge to optimize and tweak every system in my home.

smart appliances for the smart grid

I've been talking a lot about energy usage in this post but I'm really referring to electricity usage.  There are several other sources of energy usage in my home.  There is natural gas, water and even diesel fuel for my fleet of diesel vehicles.  The ultimate monitoring system will include monitoring for all energy and resource systems.  For some homeowners or renters, they must also consider propane, heating oil, wood pellets and even solar and wind.  In the future, I hope to have advanced monitoring that can provide data on all of these sources of energy and, in an ideal solution, the ability to control and adjust the levels based on user interaction or the surrounding climate.  See my post on the Solar Decathlon homes to learn more about the future of monitoring and systems control.

In summary, by installing real-time energy monitors, homeowners can empower themselves with more knowledge of how they use energy in their home that will take them beyond the basics of tracking monthly utility usage.  This knowledge can be used to optimize their energy usage and both reduce their energy usage and change the types of energy they use.  Stay tuned for Part III of Energy Tools for Newbies to learn how to find quick wins that will help improve energy consumption in the home through use of the tools described in our Energy Tools for Newbies series.