Home Energy Monitors

Home Energy Monitors, that is, devices that display a home’s energy consumption have been touted as Silicon Valley’s contribution to the national energy conservation effort. A Home Energy Monitor (or HEM) constantly informs the occupants of their home’s electricity and gas consumption, along with conversions to monthly costs and comparisons with previous periods. Some models can (or will) communicate with heating and air conditioning systems. These devices will enable consumers to more carefully manage energy consumption and quickly identify energy wasteful practices. A better-informed consumer, the theory goes, will take more actions to reduce energy use. This scenario is consistent with our belief that if we deliver energy information to the consumer they will act upon it.

Unfortunately an article in this issue suggests that HEMs don’t automatically save energy (see “The Net Impact of Home Energy Feedback Devices,” p. 20). In fact, the energy savings were, as the authors succinctly concluded “not statistically different from zero”. Furthermore, the participants in the study were highly motivated and actually paid to get the meters. If these consumers don’t save energy then what can we expect from the larger population? This evaluation is not alone: a soon-to-be-released report reviewing a large number of studies found similar results. Other evaluations in Europe and Japan also observed little or no energy savings from HEMs.

HEMs suffer from a variety of drawbacks, ranging from clunky user interfaces to voracious appetites for batteries. At least one cynic has called the HEMs “a technology in search of a problem” because monitoring a home’s energy use appears to be a wonderful application of advances in local networks and low-cost processing. HEMs today are also dropped into a lonely, inhospitable world where few other devices communicate with the same protocols (if they are able to communicate at all).

One underlying problem is that energy consumption events occur relatively slowly and rarely require the bandwidth of a webcam or audio stream. Put another way, watching home energy use on a display or on the Web is boring. Most people lose interest pretty quickly. The high attrition rates found in the Oregon study demonstrate this phenomenon.

Meanwhile, we haven’t exploited the information flows that are already in place, such as monthly energy bills. An experimental project in Gainesville, Florida, demonstrates how disclosure of monthly energy information can encourage friendly competition among neighbors. And, beyond competition, people can learn that their neighbors enjoy lifestyles similar to their own but with dramatically less electricity, natural gas and water. This is a first step towards reducing energy use.

In spite of the negative results so far, I still support the development and installation of HEMs. The technology is so cheap that a HEM can pay for itself even if it saves only a few percent of energy use. A HEM may pay for itself by alerting users to high peak electrical use where utilities charge extra for it. A HEM can also serve as a useful diagnostic tool (and data logger for a high school science project). In the long run, the HEM will become less lonely when appliances are able to communicate and provide information that consumers actually find useful. All of this calls for much stronger pressure on manufacturers toward harmonization of communications protocols and greatly improved user interfaces.

But we shouldn’t fool ourselves, consumers aren’t going to check the displays of their HEMs like they visit their Facebook pages, and HEMs are going to save, at best, a tiny amount of home energy.

- Alan Meier