Many manufacturers of consumer products now offer sustainable options that have a lower carbon footprint or that use recycled or plant-based material for their packaging. How come we don’t all buy these alternatives en masse? One explanation is that we are, at heart, economists, who trade off the green features of what we buy with other characteristics, not least the price. But most environmentally friendly alternatives are not (much) more expensive than the conventional equivalent, so why is the takeup of these products still rather modest?

Research by Siv Skard and colleagues at the Norwegian School of Economics set out to build a deeper understanding of what might encourage or discourage us to buy sustainable products. One of the phenomena the researchers wanted to investigate is the so-called ‘sustainability liability effect’, which describes consumers’ presumption that sustainable products are less effective than conventional substitutes. In particular for so-called strength-dependent products (like kitchen cleaners or drain unblockers), consumers might reason that the most efficacious ingredients are environmentally damaging, and therefore the environmentally friendly variant does not perform so well, or that the resources spent on making a product more sustainable are diverted from improving its quality. The research also explored to what extent the nature of the packaging material (rather than the core product itself) influenced consumer perception.

Across four experiments, both in the lab and in the field (where they showed shoppers in a shopping mall mock-ups of products), the researchers uncovered a diverse picture of how consumers respond to environmental claims by manufacturers.

For the strength-dependent category, green product credentials were clearly a liability: on average, participants thought they’d need more of the sustainable product than of the non-green one, both when they were simply asked the question, and when they had to measure off the quantity of product they thought was needed. (There was also evidence of a contagion effect from packaging to product. Participants inferred lower functional quality of products presented in recycled material, even if no sustainability claims were made about the product itself. However, this effect was weaker than for green product features.)

For gentleness-dependent products, the findings were more nuanced. As expected, there was a sustainability asset effect (i.e., sustainability claims enhance the perception of product performance, at least if they are linked to the core function of the product). The positive effect of sustainable packaging on product perception was much weaker, and for some participants it was even a liability.

Another interesting observation was that sustainability itself is not a simple characteristic. For packaging, participants rated the functional quality of a gentleness-dependent product resented in recycled packaging materials as significantly lower than the non-green product. When the product was presented in “100% plant-based packaging material” the effect was positive, although not statistically significant. The researchers hypothesize that recycled materials are associated with waste material and are not as suitable for personal care categories as plant-based materials.

Finally, as the researchers also asked the participants whether they thought it was important to them to purchase environmentally friendly products, they were able to test for the potential moderating influence of a (self-professed) “green profile”. For strength-dependent products, this seemed to make no difference with respect to the perceived product quality (regardless of their green self-image, all participants thought the non-green product would perform better). Everyone also preferred the non-green product over the green product, but people with a green profile did prefer the non-green product in green packaging.

For gentleness-dependent products, such as body lotion or baby shampoo, in contrast, there was a difference: green-profile participants preferred the green product, while the others preferred the non-green one. This suggests that people who see themselves as environmentally conscious may effectively be making a pro-environmental trade-off, sacrificing product quality for sustainability. However, as the researchers point out, participants may have been influenced by social desirability bias, and their behaviour may well align more closely with their less green fellow shoppers when it comes to actual purchases.

This research illustrates that sustainability is not a simple characteristic. It acts as a liability for strength-dependent products and as an asset for gentleness-dependent ones. Sustainable packaging for a conventional product can damage the perception of quality in both categories.

In practice, this means that the effect of claims of sustainability is not necessarily easy to predict – even the strength-dependent and gentleness-dependent categories are quite coarse. In which category would consumers place anti-dandruff shampoo, or washing-up liquid? And how would they map these perceptions about products on services? Would prospective hotel guests perceive the cleanliness of their bathroom or their sheets differently if the establishment claimed it only used green products for cleaning?

We should also not overlook the broader context: consumers may react quite differently to a niche brand that has built a solid reputation around environmental and social sustainability, and a traditional one whose reputation is of dependability.

In such a complex landscape, the consumer response to sustainability claims is not easy to predict. Simply offering sustainable products and services is not enough. To successfully shift consumption patterns, it is important to understand the specific trade-offs consumers make, and develop the right approach to change it.

Related: Read ‘Nudging’ for a More Sustainable Future