In this paper we argue that unsustainable behaviors often stem from a common averaging bias when people estimate the environmental impact of a set of environmentally friendly and less friendly objects or actions. In Experiment 1, we show that people believe that the total carbon footprint of a category of items (a community of buildings in this case) is lower, rather than higher, when environmentally friendly (“green” buildings) items are added to the category, a negative footprint illusion. Experiment 2 showed that the carbon footprint estimate assigned to a category with a mix of environmentally friendly and less friendly objects (“green” and conventional buildings) is the average of its subsets (the “green” buildings and the conventional buildings, respectively), an averaging bias. A similar averaging process may underpin estimates of the environmental impact of people's own actions, explaining why people believe that environmentally friendly actions can compensate for less friendly actions.

Recent years have seen a marked increase in carbon emissions despite pledges made by the international community at the Paris Accord in 2015 to reduce fossil fuel production and consumption. Rebound effects could contribute to this phenomenon as, in which attempts to curb carbon emissions might have inadvertently led to an upswing in fossil fuel usage. The present study hypothesizes that rebound effects are driven by a misapplication of compensatory balancing heuristics, with the unintended outcome of producing inaccurate estimates of the environmental impact of “green” or environmentally friendly labelled products or behaviors. The present study therefore aims to investigate the relationship between participants’ degree of compensatory thinking (e.g., “Recycling compensates for driving a car”) and their susceptibility to the Negative Footprint Illusion, a widely replicated phenomenon demonstrating that the presence of “green” products biases carbon footprint estimations. One hundred and twelve participants were asked to complete a 15-item Compensatory Green Beliefs scale and to estimate the total carbon footprint of a set of 15 conventional houses, followed by a set that included 15 “green” houses in addition to 15 conventional houses. Results indicated that participants, on average, believed that the “green” houses were carbon neutral, and that susceptibility to the Negative Footprint Illusion was predicted by performance on the Compensatory Green Beliefs scale. This is the first study confirming that individual differences in cognitive processes (i.e., Compensatory Green Beliefs) are indeed related to inaccurate estimates of “green” products, providing a foundation for further investigation of the influence of “green” and compensatory beliefs on carbon footprint estimates.

People’s belief that one or more environmentally friendly items that are added to a set of conventional items can reduce the total environmental impact of these items (the negative footprint illusion) could lead to unwanted environmental consequences. An averaging bias seems to underpin this illusion: people make their estimates based on the average of the environmental impact produced by the items rather than the accumulated sum. We report four studies that used various priming manipulations to explore whether people’s preoccupation to think in terms of an average can be eliminated by fostering a summative mindset. The results demonstrate that participants avoid succumbing to the negative footprint illusion when the critical judgment task is preceded by tasks that engender a summation judgment. Our evidence indicates that the negative footprint illusion can be tempered when a primed concept (summation) is used adaptively on subsequent judgments, thereby correcting for bias in environmental judgments.

Previous research has shown that merely calling an indoor environment environmentally certified will make people favor that environment over a conventional alternative. In this paper we explore whether this effect depends on participants deliberately comparing the two environments, and whether different reasons behind the certification influence the magnitude of the effect. In Experiment 1, participants in a between-subjects design assigned higher comfort ratings to an indoor environment that had been labeled “environmentally certified” in comparison with the exact same indoor environment that was unlabeled, suggesting that the effect arises even when participants do not compare the two environments when making their estimates. The results from Experiment 2 indicate that climate change mitigation (as the reason for the certification) is a slightly better trigger of the effect compared to climate change adaptation. The results suggest that studies on psychological effects of “green” buildings should experimentally control for the influence from participants’ judgmental biases.