Using Social Norms to Reduce Household Energy Consumption
Schultz P. W., Nolan J. M., Cialdini R. B., Goldstein N. J., Griskevicius Vladas (2007). The Constructive, Destructive, and Reconstructive Power of Social Norms. Psychological Science, 18(5), 429-434.
In the two projects described below, information was delivered to households in order to foster norms that support reduced electricity consumption. These projects made use of two types of norms, descriptive and injunctive. Descriptive norms refer to perceptions of what is commonly done. They signal mainstream behavior. Frequently, people do not want to be outside the mainstream. Distinct from perceptions of what is commonly done, injunctive norms refer to perceptions of what should or should not be done by individuals within a culture (i.e. approved or disapproved behavior). The first project was carried out on a small scale in the City of San Marcos, California, while the second project was carried out on a much larger scale by the Sacramento Municipal Utility District.
San Marcos, CA
In 2005, researchers provided normative information to several hundred households in the City of San Marcos and observed the effect on the households’ energy consumption over a period of four weeks. At the beginning of the four-week period, households received two door hangers, delivered one week apart. Each door hanger displayed:
• handwritten information about how much energy, in kWh/day, the household had used in the previous week;
• descriptive normative information about the actual energy consumption of the average household in their neighborhood during that same period; and
• pre-printed suggestions for conserving energy (e.g. use fans instead of air conditioning).
Households in this project were in one of four experimental conditions. The researchers drew a happy face, an injunctive normative message implying approval, on the door hangers delivered to half of the households whose energy use was lower than the neighborhood average. The other half of the low energy users received just the information listed above. The researchers drew sad faces, implying disapproval, on the door hangers delivered to half of the households whose energy use was higher than average. The other half of the high-energy users received only the standard information.
Three weeks after receiving the second and final door hanger, households who had higher-than-average electricity use at the outset of the campaign, and who had received information that included a sad face, had reduced their electricity use by 6.0 percent. Higher-than-average electricity users who received the standard information without the sad face had reduced their usage by 4.6 percent. This difference from baseline was found to be non-significant.
Households that had lower-than-average electricity usage at the outset of the campaign had increased their electricity consumption three weeks after receiving the second door hanger. However, those that had received a happy face in addition to the standard information increased their usage by only 1 percent, a statistically insignificant amount, while those that did not receive a happy face increased their use by 10 percent.
The approval conveyed by the happy face proved effective in motivating the better-than-average electricity users to maintain their low-consumption behavior, rather than drifting towards the behavioral standard represented by the average daily household electricity usage in the neighborhood. The disapproval conveyed by the sad face, when combined with the descriptive normative information, proved more effective in motivating the worse-than-average users to bring their consumption in line with others than did the descriptive normative information alone.
Department of Psychology
California State University
San Marcos, CA 92078
Sacramento Municipal Utility District
The Sacramento Municipal Utility District (SMUD) provides electricity to 600,000 residential and commercial customers in the City of Sacramento, California, surrounding Sacramento County and a small portion of Placer County.
In a pilot launched in April, 2008, SMUD began sending monthly Home Electricity Reports to 35,000 randomly selected residential customers representing a broad cross section of ages, incomes, sizes of homes and other factors. A control group of 60,000 customers was also randomly selected. Both groups were exposed to district-wide marketing of SMUD’s energy efficiency programs and services, but only the test group received the Home Electricity Reports. The text and graphics in the reports were pre-tested with real customers in home interviews that lasted several hours.
The report received by each household displayed bar graphs that compared the household’s monthly and annual electricity usage to the average usage of:
• 100 nearby homes of similar size that used the same heating fuel; and
• 20 comparable, highly efficient homes nearby.
Households with lower-than-average electricity usage found a happy face in the energy efficiency score box on their report. The 20 percent of households with the lowest usage received two happy faces. The utility initially displayed a sad face on the reports sent to higher-than average electricity users, but stopped using them after a few customers got upset.
The reports also recommended specific energy-saving opportunities for each household and showed them what they could save if they decreased their electricity usage to the level of the 20 most efficient comparison households. Demographic information was used to tailor the recommendations prepared for each household. For example, renters would not be advised to implement measures that a building owner would normally be responsible for, such as upgrading heating equipment.
If, at some point during the pilot, a household participated in a SMUD energy efficiency or renewable energy equipment rebate program, the group of households to which they were compared was modified. The new comparison group was constructed of similar households that had also participated in such programs. The goal was to provide each household with normative information that would continue to motivate them to improve energy efficiency.
OPOWER Inc. (formerly Positive Energy), a Virginia-based company, conceived of the Home Electricity Reports and produced and distributed the Reports for SMUD.
Six months after the pilot began, SMUD conducted an initial assessment of the strategy’s effectiveness in reducing electricity consumption. It found that customers who had received the Home Electricity Reports reduced their electricity use by 2 percent more than those in the control group, or three gigawatt hours in total. That is equivalent to removing 700 homes from the electricity grid. After thirteen months, a second evaluation showed that the 2 percent electricity use reduction continued to be sustained.
People reduced their consumption mostly by making small changes, such as turning off lights and adjusting their thermostats. The data analysis also showed that even those households notified that they were in the top 20 percent of energy savers continued to try to achieve additional savings.
The results of the SMUD pilot suggest that a long-term reduction in electricity use can be sustained if householders receive repeated reminders. More frequent reminders correlated with increased energy savings. When SMUD experimented with sending quarterly rather than monthly Home Electricity Reports to some residents, they saw the savings begin to deteriorate during the three-month period between reports. Electricity savings went back up as soon as residents received the next quarterly report. Monthly reports were not three times more effective than quarterly reports, however. SMUD and OPOWER Inc. are in the process of determining the most cost-effective frequency for Home Electricity Report distribution.
The Home Electricity Reports cost $.03 for every kWh reduced, which is one-half the cost of producing electricity from clean coal and one-tenth the cost of production using solar panels.
As of early 2009, this normative informational strategy was being piloted by utilities in at least ten other major metropolitan areas in the United States.
Sr. Director, Marketing & Strategy
References for Sacramento Municipal Utility District Pilot
Bowman, Chris. (2008, September 26). SMUD Rates Customers on Energy Consumption. The Sacramento Bee, pp. 3B. Retrieved April 10, 2009 from http://www.sacbee.com/101/story/1267187.html.
Crane, Barbara. SMUD: Sixty Years of Energy Conservation. Green Technology Magazine. Retrieved April 10, 2009 from http://www.green-technology.org/green_technology_magazine/smud.htm.
Kaufman, L. (2009, January 31). Utilities Turn Their Customers Green, With Envy. New York Times. Retrieved March 20, 2009 from http://www.nytimes.com/2009/01/31/science/earth/31compete.html.
Kavazovic, Ogi. Sr. Director, Marketing & Strategy for OPOWER Inc. (formerly Positive Energy). Personal Communication on April 17, 2009.