would be the most credible and useful. The question is not trivial. In the first study of residential display meters, the feedback had no effect (Becker et al., 1979)—possibly because feedback was given (in cents-per-hour) at two-second intervals. This method showed major changes in energy use only when appliances were shut off entirely.
Useful feedback might also be delivered to households through an improved utility billing system. Research on this issue, while limited, shows that it has some promise as well as some problems (Russo, 1977).15 A few studies have also examined the use of energy consumption feedback in motor vehicles. They are somewhat promising, showing small fuel savings in the 5 to 10 percent range from the installation of devices to monitor fuel use on cars and trucks (Stern and Gardner, 1981; Reichel and Geller, 1981). It is reasonable to expect that the effectiveness of feedback on fuel used in vehicles will depend on some of the same variables as for home energy use: credibility of the feedback; commitment and the setting of goals; frequency; and the importance of fuel costs in the user’s budget.
Feedback systems for making energy visible have a potential advantage over verbal information and advice in that they can be made credible independently of the issue of trust in an information source. While a utility’s motives may be mistrusted when it sends advice on how to save energy, its meter readings are usually accepted as definitive. Therefore, feedback systems may be important independently of issues of trust.
Because houses and apartments vary so much in their structural characteristics and because their energy requirements also depend on climate, the cost of fuel used, the stock of appliances in the home, and the behavior of their occupants, most recommendations for energy-saving activity in “all homes” are likely to be inappropriate for many households. Technical experts in residential energy conservation have long recognized this and have developed the concept of a home energy audit specifically to handle the problem of diversity—to give householders expert advice suited to their individual situations.
Over almost a decade, various programs to provide individualized energy information through home energy audits have existed in the United States. Some of them have been based on short building surveys, filled out by residents and analyzed by computer to give recommendations for action. These “Class B” energy audits typically give the householder information on the estimated costs of each suggested action (if installed by a contractor or if done with the resident’s own labor) and some simple measure of expected return on investment—either estimated dollar savings per year or an estimate of the number of years it would take the investment to pay back its cost at current energy prices. Class B audits are an inexpensive