February 1, 2011 | 13
Editor’s Note: Scientific American‘s George Musser will be chronicling his experiences installing solar panels in Solar at Home (formerly 60-Second Solar). Read his introduction here and see all posts here.
"I was bleeding energy out," fellow solar homeowner Paul Proctor told me. "I needed to find out how, and why, and where." I can relate. Even though I’ve worked hard to seal up my house and drive a stake through electricity vampires, I still can’t bear to open my monthly utility bill. So I continue to seek out energy forensics tools to ferret out where energy is going and what I can do to stop it from going there. Proctor has been trying out the FIDO Home Energy Monitoring System from EcoDog and he related his experiences to me last week.
In past posts, I’ve raved about the Kill-a-Watt, a module you plug into a wall outlet to display the power draw of the appliance using that outlet, and The Energy Detective (TED), a coil of wire that clamps around the power cables coming into your house to record your total consumption. Both devices have spawned imitators, and fellow energy blogger Chris Kaiser keeps a excellent list. A study in northern Ontario in 2006 found that TED-like monitors encouraged families to reduce their electricity consumption by an average of 6.5 percent.
But the TED tells you only how much and when, not where the energy is going. It’s a pain to go around the house plugging and unplugging the Kill-a-Watt to track down the culprits. I’ve longed for something that combines the automatic data-gathering of a whole-house monitor with the appliance-level detail of a plug-in module. So I was intrigued last year when two products came out that promised to do exactly that: the EcoDog device and the eMonitor from Powerhouse Dynamics.
Proctor, who lives with his wife and daughter in San Diego, was one of EcoDog’s first customers. He said he became aware he had a serious energy problem when he got to talking with his neighbors about their electric bills. (I guess in San Diego, you can’t make small talk complaining about the weather.) Most were $100 a month or so. His was twice that. (In general, I think we could all learn a lot by sharing our energy experiences, both offline and on. Microsoft Hohm is one way you can do this.)
FIDO works much like TED. Its main innovation is that you clamp a coil of wire around each circuit in your breaker box rather than just the main cables (see photo at left). This coil, known as a current transformer, magnetically registers the current flowing through the circuit. It is attached to a monitoring device that takes readings at regular intervals and transmits them to a USB computer interface. Like TED, the EcoDog device uses the household electric wiring for its transmissions. Proctor said the transmission has been completely reliable, but I suspect that someone running electronic devices that also transmit over the power line, such as home automation equipment, would run into trouble and might need to install noise filters, as I had to do with TED.
The computer app (Windows-only, alas, though a Mac version is planned for later this year) shows a floor plan of the house with all the data arrayed around it. The way Proctor described it, it’s an energy geek’s dream. You can study your patterns of electricity use and find places to cut back. Proctor’s biggest power sink turned out to be a water pump for a decorative pond in his backyard—it accounted for fully half his total electric bill. "I certainly shocked my family when I showed them how much energy was being burned," he told me.
Another use, EcoDog’s president Ron Pitt told me, is to watch for changes in appliances’ power draw as an early warning sign they need fixing. A third application, as my colleague Larry Greenemeier wrote about yesterday, will be to monitor electric-car charging. Proctor has ordered a Nissan Leaf, and FIDO will let him break out the charging costs from the rest of his household power consumption.
On the downside, the EcoDog system, unlike TED, doesn’t interface with Google Powermeter, so you can’t watch your household consumption remotely—say, from your office. The biggest shock, however, is the price tag. Proctor said he paid $1,800 for 16 circuits. You can get the system for $1,300, but that doesn’t include installation if you don’t feel up to it yourself (and you shouldn’t, if you don’t have experience with electrical service panels). The eMonitor is nearly the same price ($1,200) for a roughly comparable system. Depending on the state of your household wiring, you might incur other costs. In an old house like mine, there’s very little logic to how the outlets, lamps, and appliances are grouped together. If I wanted to break down my usage room by room or appliance by appliance, I’d need to shift some outlets from one circuit to another.
Few homeowners can justify these systems based solely on the expected savings, unless, like Proctor, they can slay a serious hog. For now, these monitors are in the realm of fun gadget.
A basic issue is that lamps and most appliances use a piddling amount of energy compared to heating and cooling, at least for those of us who live in climates less blessed than San Diego’s. What would really justify spending money on is an energy monitor for heating and cooling. Surprisingly, none yet exists. It would take a sensor to monitor gas or electric use, a few strategically placed thermometers, and a computerized thermal model of the house. Such a system would conduct an ongoing energy audit of your home. For instance, you might find that some areas are systematically colder, suggesting a need for better insulation. Temperature differences between rooms might signal problems with the air ducts or radiator venting. Temperature differences between upstairs and downstairs might indicate that the house suffers from a chimney effect and would benefit from air sealing in the basement and attic.
I bet a $1,000 thermal-monitoring system could pay for itself within a single season. With that data, you could also see whether super-expensive steps such as deep energy retrofits or geothermal heat pumps would justify themselves. Until someone develops such a system, though, I think you’d still benefit from one of the cheaper power monitors.
Photos courtesy of EcoDog