Concern over ecologically unsustainable levels of private consumption has become prevalent during the past few decades in Western countries. Household consumption expenditure has increased in the EU-15 by almost one-third per person between 1990 and 2002. Households are also becoming smaller, so people tend to use more living space, energy and water and generate more waste per person [1]. This development increases the extent to which private households consume natural resources and is a driving force behind the current overuse of natural resources.

However, not all households are equal in terms of how much they consume. Previous research shows a clear connection between income level and the environmental impacts of consumption: people with less financial resources use less natural resources and cause less carbon emissions [2,3,4,5,6]. Therefore, we can assume that the material footprint of people living in low-income households is at a more ecologically sustainable level. Consequently, the conclusion could be made that since poor people are living at a more ecologically sustainable level, their poverty is justified. Nevertheless, all environmental policies aimed at reducing the present level of consumption should take account the economic needs of low-income households and ensure at least a decent standard of living for all members of society [7]. Sustainable development requires an awareness of the fact that ecological sustainability and social justice are inextricably linked [8]. Therefore, the aim of this paper is to evaluate both the ecological sustainability and the social sustainability of low-income households. The approach resembles the concept of “environmental space”, which describes the amount of sustainable space between the equally shared maximum rate of consumption of global natural resources while still ensuring basic needs and human dignity [9]. By drawing from previous research on what constitutes an ecologically sustainable level of natural resource use, and by using reference budgets that illustrate the social minimum required for decent living, we discuss the possibilities for achieving both an ecologically sustainable and socially decent standard of living in Finnish society.

In this study, we measured the amount of natural resource used by private households, i.e., their material footprints, based on the MIPS concept (material input per unit of service) [10,11]. The MIPS method measures natural resource use throughout the entire life cycle of products and activities by taking into account both direct and indirect material use [12]. Material footprints can be used as an indicator for comparing present levels of household consumption to long-term targets for ecological sustainability. In addition, we assessed if the consumption level of low-income households can be regarded as socially sustainable by comparing their material footprints with the material footprint of a woman below 45 years of age, based on a single household reference budget. We decided to study low-income households in the Finnish welfare state because, according to social policy goals, they should be allowed to achieve a decent standard of living, while, according to previous research [2,3,4,5,6], they can be assumed to have lower material footprints.

We present and discuss the material footprints of each of the 18 low-income households in their entirety and the different consumption components that the households need to make ends meet. With respect to the ongoing discussion about what constitutes a socially and/or ecologically sustainable level of household consumption [3,7; in terms of energy requirements, see 4], we compare the material footprints of the participating households to the material footprints calculated for the decent minimum reference budgets [13] and to the material footprints of 27 different, more “typical” households at varying income levels [2], as well as to the material footprint of an average Finn [14]. In addition, to evaluate the ecological sustainability of a particular household’s level of consumption, we compare its material footprint to the level of sustainable resource use, which we obtained based on the values originally published by Bringezu [15].

In the following section, we describe the framework for the study and assess the notion of ecological and social sustainability. Thereafter, we describe the methodology of the study and the MIPS concept for measuring the material footprint of various households. After displaying and discussing the results, we conclude by considering the contribution of these empirical results to the sustainability debate.

Sustainable development requires integrating environmental and social aspects in a way that directs policy goals and societies to an ecologically sustainable and a socially flourishing future. Ecological sustainability means living within the limits of the supporting ecosystems: the level of natural resource use should not exceed the long-term carrying capacity of nature (see [12,15,16,17,18]). Social sustainability refers to a sense of equity, an awareness of sustainability, participation and social cohesion and it emphasizes that development policies and social policies should be handled in a just and equitable manner [19,20]. The goal of socially sustainable development is to ensure a decent standard of living for every human being around the globe. This requires “meeting the basic needs of all and extending to all the opportunity to satisfy their aspirations for a better life” [21]. Socially sustainable policy goals are implemented in welfare states through various welfare programs. For instance, in Finland the social policy is aimed at supporting social inclusion and participation and ensuring a basic quality of life for all members of society by providing, for example, a minimum level of social benefits in cases of social risk, such as sickness or disability [22].

However, the present sustainability discussion lacks a profound understanding of what constitutes basic needs and a decent standard of living: What is to be ensured and sustained? What should we regard as “decent” (e.g., [23,24])? Basic needs refer, naturally, to the ability to satisfy different needs, such as the need for food and pure water, decent housing, energy and health care [25]. A decent standard of living is, nevertheless, a more complex concept, since it has to be assessed in each society in the relation to the requirements of the environment in which people live. Just as with the concept of deprivation, a decent standard of living is relative to the local community and society to which an individual belongs [26,27]. For instance, in affluent consumer societies such as Finland it includes more material necessities and a higher standard for housing and nutrition than is regarded decent in poorer countries.

One concrete way to assess the idea of a decent standard of living in terms of household consumption is a reference budget. It sets a consensus-based standard for a socially acceptable and desirable standard of living in present society by defining those goods and services that all households (whether a single individual, a couple or a family) should be able to afford. Reference budgets describe the level of consumption regarded as necessary for all members of society. According to Bradshaw et al. [28], reference budgets take into account both basic material needs and the need for social participation. In Finland, an adequate standard of living has recently been defined in the decent minimum reference budgets. These budgets were established as part of a consensual process involving both consumers (n = 53) and experts and they are based on four types of households [29]. The consumption level of the reference budgets is relatively low compared to what Finnish people spend on average. For the purposes of this study, we have calculated the material footprints for all the commodities and activities that are included in the Finnish decent minimum reference budgets (see [29]). For example, the material footprint of a single woman below 45 years of age is 20 tonnes per person in a year [13].

The reference budgets are based on current consumption patterns and the goods on offer. In many countries (e.g., Great Britain, the Netherlands and Sweden), the budgets are updated regularly, because when economy grows and more commodities enter the markets, the amount of commodities included in the reference budgets also tends to increase [29]—leading to an increase in the natural resource use of households. The growing amount of commodities and activities that constitute the elements necessary for a decent standard of living is one example of how social sustainability is promoted without taking into account the environmental challenge that we are facing. So far, the social and environmental dimensions have usually not been successfully integrated in research, in policy documents or in practice, which has led to separate and even contradictory policy targets [19]. For example, poverty reduction often requires economic growth, which might lead to an increase in material use and environmental degradation.

However, sustainable development demands that social sustainability goals be formulated in an environmentally sound manner, acknowledging that ecological sustainability is a necessary foundation for a sustainable society [8,19]. Sustainable social policy goals ought to include a target to decrease the present over-use of natural resources by reducing the harmful environmental impacts of both the public sector and private households. In addition, the social policies of Western welfare states should acknowledge that overconsumption by the rich nations is one strong driving force behind the overuse of natural resources, and that the world’s wealthy are causing serious ecological destruction in developing countries by supporting export-oriented production. In addition to the need for a more equal distribution of wealth on a national level, there is an urgent need for a more equal global distribution of wealth and a more equal use of natural resources [8,9,20,30]. Environmental justice means that intergenerational and intra-generational equity should be made congruent—on a global level [31].

Based on this future-oriented and equality-based perspective, research on material use has estimated the level of ecologically sustainable public and household consumption. One target for sustainable production and consumption has been to reduce material flows in the industrialised countries by a factor of 10 by the middle of this century [12,32]. This would make it possible to cut global material flows in half, while doubling global prosperity: it would lead to an increase in global resource productivity by a factor of four [33].

Drawing on these projections, Bringezu [15] has substantiated the sustainable level of resource use for total material consumption (TMC)—including public consumption and capital formation—of European countries by calculating that an acceptable level of abiotic resource consumption would be approximately 6 tonnes per capita in a year. In addition, he argues that the present consumption of 4 tonnes of biotic resources could probably be maintained “under conditions of sustainable cultivation”, whereas erosion should be reduced by a factor of 10 to 15 from the present level of 3 tonnes per capita [15]. Therefore, a sustainable level of total material consumption (TMC) for a European economy would amount to a maximum of approximately 10 tonnes per capita in a year.

At the level of a private household, a sustainable level of natural resource use would amount to 6 to 8 tonnes per person in a year. We estimated this level by acknowledging that in a sustainable economy, the shares of public consumption and capital formation might drop to 20–40% that of the present level (approx. 40–60% of TMC [34,35]), because household consumption could be seen as being more essential than public consumption and capital formation.

At the present level of household consumption and the material footprint generated by it, Finnish households exceed this sustainable level by a factor of 4 to 7. Previous research has estimated that the natural resource use of an average Finn is approximately 30 [36] to 40 [14] tonnes per year and that the biggest shares of this go to housing, food, everyday mobility and tourism [2,14]. In a pilot study designed to measure the natural resource use of private households, Kotakorpi et al. [2] studied 27 Finnish households, including single households and families, households from urban areas and the countryside, and households from various income levels. The results showed that the differences in the material footprints of the households ranged from 13 to 118 tonnes per capita per year, meaning that there is a factor difference of 9 between the households with the smallest material footprint and those with the largest material footprint, a factor that differed by 3 from average in both directions.

In this article, we present the material footprints of 18 single households. We sent the invitation letter only to single households because, on the one hand, a single household is the most common household size in Finland [37], and because, on the other hand, allocating the material footprint to the members of the household is unambiguous in the case of single households.

All participating households were in southern Finland and the occupant was on disability pension or basic unemployment allowance. They belonged to the lowest income deciles in society, since their income was between 400 and 1200 euros per month, whereas the average income level in Finland was 3040 euros in 2010 [38]. According to previous research, those living at a minimum income are often, relatively speaking, poor and they lack the necessities or consumption habits that are presently regarded as socially acceptable [39,40].

The natural resource use of the participating low-income households was calculated on the basis of two interviews with each household, and via consumption and standard of living questionnaires that the participants filled in during an approximately two-week period between the interviews. The participants were asked to report their income and consumption expenditures: food, housing, household goods, energy use, transport, tourism and leisure. The list of household equipment provided in the decent minimum reference budgets [29] was adapted to fit the questionnaire and used when assessing the equipment of the households being studied. The data for tourism was collected from the previous year so as to have a common and standardized time scale. During the interviews, we were able to fill in information that was missing in the questionnaires. Because the interviews were conducted by visiting the participating households, we were even able to observe the number and types of household appliances that the participants had. The interviews thus improved the reliability of the data collection.

The natural resource consumption of the households was calculated as the material footprint [41]. The material footprint is based on the MIPS concept [10,11,12], which takes into account the entire life cycle of products and activities and includes direct resource use (used extraction) as well as indirect resource use (unused extraction) in relation to the benefit provided [42,43]. The material footprint is calculated by multiplying the direct resource consumption or other input (e.g., electricity or transportation) by a material intensity factor (MIT factor) specific to each input [41]. Most of the material intensity factors used for the calculations were based on previous research [2,41,44]. In addition, some MIT factors (e.g., for health care and hairdressing) were estimated for the purposes of this study.

We chose the material footprint based on the MIPS concept as a measure for assessing and comparing the ecological sustainability of the households for several reasons. First, the MIPS concept and the material footprint can provide a rough indication of the long-term ecological sustainability of consumption patterns when compared to estimates for a sustainable level of natural resource use (see also Section 1).

Second, the material intensity values and factors used here are based on micro-level, life-cycle inventories, which provide us with a realistic and holistic view of the entire life cycle [10,11]. In addition, measuring both direct and indirect resource use (used and unused extraction) (see [42,43]) strengthens the life-cycle perspective. This also means that the approach covers all material flows that are a part of the human economy, including the material flows required for providing energy. This makes the MIPS approach more complete than, for instance, an ecological footprint or a carbon footprint, even though the material footprint does not directly account for land use.

Third, as a micro-level calculation approach, the MIPS concept can be used for modeling the activities of specific households at a greater level of scrutiny than when using macro-level approaches such as MEFA (material and energy flow accounting, see [45]) or TMC (see above)—provided that a sufficient amount of data is available for modeling the households. In this study, the relatively good availability of public data on the resource intensity of household-related products and activities enabled us to employ the material footprint and MIPS approach. Earlier research projects in Finland [2,14,46,46,47,48] provided an adequate database for most of the data needed in this study.

In this paper, resource use is calculated using mass units of TMR (total material requirement). The TMR is the sum of abiotic and biotic resource use plus the topsoil erosion related to agriculture and forestry [11]. Hence, the TMR does not include the resource categories of water and air. Although we calculated these resource categories as a part of this study, we opted not to include them in the current article for two reasons. First, the way in which water resources and also climate-related air are calculated is still the subject of much heated debate (see e.g., [42]), so that the contribution of this article would probably be less relevant in these fields. Second, the debate regarding planetary boundaries and a sustainable level of resource use is less advanced in the fields of water and air use than are Bringezu’s [15] contributions to the debate regarding what constitutes a sustainable level of TMC.

We also compare the material footprints of low-income households to the material footprints of the decent minimum reference budgets [13]. In this study, we used the budget of a single woman below 45 years of age as a point of comparison. Another reference point is the material footprint of an average Finn, which is based on average statistical consumption data and, where this was available, on plausible data from case studies (see [14]). It would also have been interesting to compare the results of this study to the material footprint of households that especially consider themselves to be ecologically friendly. However, previous research has revealed difficulties in defining a precise material footprint for such households because even households that consider themselves to be ecologically friendly show widely varying levels of natural resource use [46].

The material footprint of the low-income single households ranged from 7 to 35 tonnes per person in a year. Hence, they all consumed fewer natural resources than an average Finn. In most cases, the material footprints were lower than the material footprints calculated for the decent minimum reference budgets [13] and lower than those of many of the households with varying income levels studied by Kotakorpi et al. [2]. Regardless, 17 of the 18 participating low-income households were still consuming at least two times more resources than an ecologically sustainable level would allow for in the longer term.

The results represent a standard of living that is both socially and ecologically unsustainable: we found both deprivation and overconsumption. Thus, it can be concluded that the present material footprints do not fall within the necessary environmental limits [9, see also 47]. Accordingly, the conclusion can be made that since even low-income households exceed an ecologically sustainable level of material use in contemporary Finnish society, social sustainability cannot be improved by increasing the amount of natural resources used by low-income households without accumulating ecological destruction. This leads us to ask, what are the implications of the results for future policies and the sustainability debate in general? How could household consumption become more sustainable?

First, measuring the material footprints of households reveals that material footprints, especially for housing and everyday mobility, are highly dependent on infrastructural factors (see also [2,47,48]). However, especially in the case of infrastructure, private households have only limited possibilities to reduce their natural resource use (see also [2,3,15]), and, therefore, a sustainable level of resource use cannot be achieved solely by the choices, decisions and activities of private households. Rather, governments and companies must improve the conditions and technologies that enable households to consume in a more sustainable way. Hence, sustainable consumption should be achieved through changes in the supply of products, services and infrastructure, e.g., in housing and the energy sector (see e.g., [50]).

Second, reducing the level of natural resource use of the participating low-income households would be socially unsustainable in contemporary society. One way of improving the social sustainability of the participating households would be to increase the level of household consumption of people living on minimum income by increasing their social benefits. This would allow them to develop a decent standard of living, and if done, for instance, by increasing taxation, it might decrease the inequality in society. If we were to compensate the increase in the resource use of low-income households by decreasing the resource use of other households, we would at least be closer to a sustainable situation. As Wilkinson and Pickett [51] have argued, equality in society supports the environmental policy goals of reducing consumption, because there is less pressure to maintain social status by increasing the level of consumption, or trying to catch up the consumption level of richer households. On the other hand, a more generous social policy often requires a growing economy in terms of GDP, and this can be controversial with respect to the targets of reducing the overall use of natural resources. The conclusion could be made that in order to be sustainable, we can no longer afford to alleviate relative poverty in Western welfare states via economic growth (see [52]).

Third, the results lead us to a serious rethinking of the concept of a decent standard of living. On the one hand, the comparison of the material footprints with the reference budgets offers some promising insights. The material footprint calculated for the decent minimum reference budget is approximately half that of an average Finn, which means that the present average material footprint of households in Finland (approx. 40 tonnes per person) could be halved while still retaining the possibility to satisfy basic needs and ensure social participation.

On the other hand, the material footprints would still exceed a sustainable level of natural resource use: even the present decent minimum level is too high for a globally equal and ecologically sustainable future. Although reference budgets are about “fulfilling needs and not wants” [28], in affluent consumer societies like Finland the decent minimum consumption level considers more than just necessities for satisfying basic needs. Essential consumption has become relative, which makes it more challenging to define (e.g., [53]). Delimiting the boundaries of needs and wants is difficult when consumption possibilities tend to increase and new goods, such as different cell phones, enter the market and become “necessities” for socializing and going on many errands. Without questioning the needs for subsistence and affection, for instance, it is obvious that we need different strategies for fulfilling those needs than merely increasing the amount of material possessions [23]. The issue of satisfying needs must be “de-coupled” from material use more efficiently than is the case nowadays.

In this study we have used the decent minimum reference budgets as a measure of social sustainability, but we acknowledge that they are only one possible approach for assessing social sustainability in terms of the adequacy of living standards. Besides this, a socially sustainable standard of living could be understood from a capability perspective as the various “doings and beings” a person is able to achieve, and it could include social possibilities, like the provision of public services (see [24,27]). In addition, a decent standard of living could be understood more universally. The estimates for an ecologically sustainable level of natural resource use take into account the needs of the entire global population and future generations. We suggest that “decency” should also be assessed more universally, for instance based on the universal basic needs defined by Doyal and Gough [54], or by setting a minimum threshold for basic capabilities, as Nussbaum [55] has proposed. The concept of a more universal and ecologically sustainable decent standard of living would be worth further research.