Sustainable Consumption on Different Levels
Product Level: From Functional Unit to Needs Fulfilment
Comparative product LCA studies analyse the life cycle wide impact products per functional unit of each product; i.e. in relation to “which function(s)” each product provides, “how much” of the function, “how well” and for “how long”. This basis serves to compare alternative products.
In a consumption perspective, and particularly for consumer products, it makes
sense to expand this functional unit also to the human needs fulfilment: The direct
function of a product ultimately serves to meet a range of human needs. While its primary, technical function of many or most products typically relate to only one of the physical basic needs, e.g. mobility, housing, or food, it always contributes also to meet other, psychological basic needs, such as for example affection, participation, and identity (Max-Neef 1991). The relevance for consumption decisions to meet also needs such as “identity” can be illustrated by the relevance that brands have in clothes consumption decisions. This example also illustrates that it will be an individual judgment how well a product meets these “soft” needs.
Person or Household Level: Sustainable Lifestyles
Moreover, it should be highlighted that needs fulfi is often done rather by complex activities, that involve different products in a specifi combination that create a new quality, rather than by simply consuming each of them: a simple walk in the park may involve a combination of outdoor clothing, maybe an umbrella, a bus trip to reach the park and for the way back, using the restaurant service to have a cake or ice-cream etc. and – important in the context of secondary consequences – involve an individually decided period of time. While the distance walked and the life time of the shoes have some relevant causal relation, otherwise the duration of many activities can be largely independent from the actual consumption of goods. Particularly the fulfi of higher needs are less directly related to product consumption, other than more basic needs such as food and shelter.
In view of efforts to a more sustainable consumption and lifestyles, it is important to consider that very different activities – using possibly also the same amount of the household resources, but with a hugely different environmental impact – may still contribute to the same degree to the needs fulfilment and happiness for the same individual person. Using leisure time and money for meetings our “soft” needs can differ as much as taking a longer motorbike ride, playing a game on a smartphone, or practicing yoga, depending on the person's preference. Also meeting our physical basic needs can be done in different ways, while again using the same amount of the other household resources. One of the possibly most widely discussed component of sustainable consumption is eating vegetarian versus a meat-rich diet. As another example, for the need shelter/housing, zero-energy houses have much lower overall life cycle impacts than less well designed and insulated houses, possibly at the same total cost of ownership.
On the next more complete level, we look at the entire consumption of a person or it's household. We agree with the literature that the individual will aim at optimizing the use of his or her household resources to achieve a maximum fulfilment of the needs. Which needs are considered how relevant and how well the individual understands which products best contribute to fulfil these needs, is obviously different for each individual.
The quantification of the impact of consuming a product, i.e. including the many secondary consequences, carries a very high uncertainty, as illustrated in the preceding chapters. Somewhat surprisingly, a much more accurate guidance can be given to individuals if looking at the entirety of consumption: The sum of all consumption – e.g. in form of lifestyle scenarios – has no secondary consequences across the person's available household resources, as they are all covered in the total by definition. This allows to build scenarios of different lifestyles and calculate and compare their overall environmental impacts.
Some limitations will still reduce the accuracy and precision of the results of
• Accurate LCI data are not available for many specific products yet, respectively approximations are less precise, and available data from different countries is not widely interoperable (see e.g. the findings of a recent survey among National LCA databases globally in Wolf (2014c))
• Secondary consequences on society level are not covered or including them adds a relevant uncertainty, e.g. changes in road congestion if the individual uses public transport instead of a car.
• Effects on changing consumption patterns upstream of the supply-chain, i.e. at those individuals that earn extra income by contributing to the production of the purchased goods.
• Finally, the calculation of how well the specific lifestyle fulfils any specific person's needs will have a high uncertainty.
However, defining alternative lifestyles and assessing their overall environmental impact and utility, using the approach proposed in Sects. 2.7 and 2.8, will allow individuals to reflect on his/her own lifestyle and allow to adopt or adapt a more sustainable one. In summary, sustainable consumption decisions mean to meet the same needs in a less impacting way without overly triggering secondary consequences by changing the available household resources.