SciTech

Study shows public perceptions on saving energy may be skewed

Credit: Maria Raffaele/Art Editor Credit: Maria Raffaele/Art Editor

It turns out that the simple practice of turning out the lights is not saving as much energy as we think. In fact, we think we’re saving about three times more energy than we actually are when it comes to our common energy-saving activities.

A study published in the Proceedings of the National Academy of Sciences this past July surveyed over 500 participants about how much energy they believed they were saving from performing certain tasks such as turning out the lights, working on a laptop rather than a desktop computer, or switching to energy-efficient appliances.

Cliff Davidson, a professor in Carnegie Mellon’s department of civil and environmental engineering and a co-author in this study, commented on the importance of this kind of study. “If people have a poor understanding of the amounts of energy used by each of their choices, they will not be able to factor in energy use as one of the variables affecting their decision,” he said.

The survey began by asking the participants to state the most effective thing they do to save energy in their lives. The responses were then separated into two overall categories. The first was curtailment, which included actions such as turning off the lights. The second was efficiency practices, which included practices such as using more energy-efficient appliances. Fifty-five percent of the respondents stated that curtailment would be the most effective way of saving energy, while only 11 percent stated that switching to more energy-efficient appliances would do the job. Thirty-four percent of the responses were too ambiguous to be separated into these two categories, and varied from “conserve energy” (15 percent), “recycle” (4 percent), to “sleep more or relax more” (3 percent). One percent of the participants stated that they simply did not know. While more people surveyed believed curtailment was more energy effective, in reality, curtailment activities like turning out the lights save very little energy in comparison to using more efficient products. These results may come as a surprise to many people.

More detailed questions in the survey exposed some inaccuracies in the participants’ energy-saving mindsets. It was found that people could sometimes predict which practices consumed more energy, but usually underestimated the magnitude of the difference. As an example, the participants correctly predicted that desktop computers consume more energy than laptop computers.

However, a discrepacy occured when researchers asked participants how much more effective laptop computers are than desktop computers. On average, people predicted a desktop computer used 1.2 times more energy, when it actually uses about 2.9 times more energy. In addition, they correctly predicted that making a can out of un-recycled aluminum requires more energy than doing so with recycled material, but incorrectly said that making a glass bottle requires less energy than an aluminum can. Actually, it takes 1.4 times more energy to make a glass bottle with un-recycled glass and 20 times more energy when using recycled glass.

There were a few areas in which participants were accurate in predicting energy comparisons, such as how much energy is saved when using compact fluorescent light bulbs. However, participants showed very little knowledge in the comparative energy saved across various activities and practices.

The authors theorized the reason the majority of the participants claimed curtailment was the best way to save energy was because switching to energy-efficient products almost always involved further research and up-front costs. To most people, it would involve less time and effort to flick off a switch than to take the time to buy a new light bulb or appliance.

More interestingly, the participants who claimed to perform more energy-saving practices were less accurate in their perceptions of energy saving. This was possibly due to unrealistic optimism about how effective their energy-saving practices were in comparison to alternative practices.

Because switching to energy-efficient products saves much more energy than common curtailment activities, there is much ongoing discussion as to how these useful energy-saving tips and information can be relayed to the public. Since results of the experiment show that many people do not fully understand how their actions affect the amount of energy saved, it is important to inform the public about energy saving practices.

Davidson suggested that “metering in real-time in residences is a good idea, so people can immediately see how much energy is consumed while they use their computer, set their thermostat to a certain temperature, or do various activities around the house.” Certainly, the transfer of this information to the general public is crucial for making beneficial, long-term energy-saving decisions.