Sustainable consumer behaviour
Sustainable consumer behavior is the sub-discipline of consumer behavior that studies why and how consumers do or do not incorporate sustainability priorities into their consumption behavior. It studies the products that consumers select, how those products are used, and how they are disposed of in pursuit of consumers' sustainability goals. From a conventional marketing perspective, consumer behavior has focused largely on the purchase stage of the total consumption process. This is because it is the point at which a contract is made between the buyer and seller, money is paid, and the ownership of products transfers to the consumer. Yet from a social and environmental perspective, consumer behavior needs to be understood as a whole since a product affects all stages of a consumption process. Consumer decision process
The buyer decision process or consumer decision process is described in three or five stages. The basic, three stage model of consumption describes obtaining, consuming, and disposing of products and services. The study of consumer decision making expands these into five stages, first described by John Dewey in 1910: Problem recognition
 Information search
 Evaluation of alternatives
 Purchase decision
 Post purchase behavior

Problem recognition
Need and want recognition occur when a consumer senses a difference between what he or she perceives to be the ideal versus the actual state of affairs. Information search
There are three key sources for searching information: personal, commercial, and public sources. Mass media, which is a public source, increasingly provides information about the environmental costs and benefits of consumption. Consumers become aware of such costs and benefits through these sources. Evaluation of alternatives
In this stage, environmental concerns which are expressed as environmental costs, risks, and benefits, will contribute to the evaluation of options as the consumer decides what to buy. One way to evaluate more sustainable consumption is to consider the total customer cost which incurs in acquisition, use, and post-use phases. Purchase decision
Consumers have to trade off the environmental benefits against other attributes such as price, performance, and design. In addition they may need to change their habitual manner of behavior. Post purchase behavior
In this stage, maintenance, repair, use frequency, and type of use are of interest. For some key products such as homes, cars, and domestic appliances, much of the sustainability impact accrues after the purchase phase during use or post-use. Post-purchase behavior may also include disposal where consumers can keep, reuse (for example by selling, trading, or giving a product to others), or dispose of a product. Some materials such as paper, glass, or metal can be recycled or reused in the production process. This phase has become important due to overloaded landfill communal waste disposal. Consumer behavior influence

Buying and consuming an individual product like a cup of coffee might seem such a trivial action that, although it refreshes us, leaves no lasting impression or memory. However, that action combines with those of other consumers to contribute to the economic success of the coffee retailer, the overall growth in the economy, and the volume of waste with which local government must deal. It influences the demand for, and the price of, coffee beans and milk, and so influences the lives and prosperity of farmers, and shapes their investment and planting decisions. It has  in terms of the demand for pesticides, fertilizer, packaging materials, and energy. The economic impact of that coffee contributes to the share price of the retailers and the levels of income and investment they will enjoy. At a national level, it contributes to national prosperity and so influences future policies on taxation and interest rates. Consumption is an economic phenomenon that addresses our individual wants and drives the economy through our collective behavior, but it is also a social and cultural process through which we express our identity and establish our place within society. It is also a physical process that consumes resources. What we eat, how we heat our homes, and how we travel to work or for pleasure may seem like nobody's businesses but our own. However, the collective consequences of such consumption decisions are a principal driver behind climate change that will have consequences for people, countries, and species across the globe. Consumers’ purchasing behavior determines the success or failure of new products and services that are marketed on the basis of their sustainability performance. Because of the role of consumers in determining sustainability impacts during the use and disposal phases of the consumption process, their overall behavior also influences the sustainability performance of all goods and services. Attitude, knowledge and behavior gap

There exist some inconsistencies in consumers’ behaviors. Attitude and behavior gap
Despite the increase in consumers’ environmental awareness, many have not changed their consumption choices and behaviors. This can be due to consumers’ selfishness, because they don't want to give up or change the way they live, or because of the associated costs and taxes. A survey was conducted in October 2020 by McKinsey & Company in ten countries (primarily in the U.S.) to determine the important factors individuals consider while deciding to purchase a product. Sustainable packaging was not highly considered compared to price, quality, brand, convenience, as well as food safety and health in regards to . Knowledge and behavior gap
There is a discrepancy between what behavior consumers think is socially and environmentally sustainable and what their behavior actually is. For instance, many people in the U.S. limit their use of spray cans as they want to minimize their contribution to the impact on the ozone layer. Their behavior is not environmentally significant because the substances that affect the ozone layer were banned in the U.S. long ago. Consumers’ lack knowledge about the environmental impacts of consumption. In the same survey 60–70% of people reported to be willing to pay more for sustainability and 35–36% would buy sustainable products if these products were available and better labeled as such. These results demonstrate a knowledge gap that prevents people from making the best choices. Consumers rely on perception and may make ignorant decisions. For example, cereal in a cardboard box is considered to be more environmentally friendly than cereal in a bag, even though the bag contains less packaging (as the box also contains a bag inside). The outward appearance of the recyclable cardboard masks the plastic inside. Three theories of explanation

Rational explanations
These theories emphasize the economics of sustainable consumption, and how consumers weigh up the functional benefits and relatively affordability of a product and service. Behavioral models based around economical rationality tend to assume a high degree of self-interest on the part of the consumer. Psychological explanations
Research into the psychology of sustainable consumption, and of the more emotional and irrational explanations of our behavior, focuses on consumers` attitudes and beliefs about sustainable issues. Three important sets of attitudes that influence consumers willingness to engage with sustainability issues are perceived personal relevance, social responsibility, and trust. Sociological explanations
Consumer behavior is also explained by how we think our consumption activities will be perceived by others, and how that might be reflect and influence our place in society. Forms

Sustainable consumption is not simply a question of what products and services are purchased, but is also about the adoption of a lifestyle in which sustainability is reflected in all aspects of consumers' behavior. Voluntary simplifiers' lifestyle is based around five key values:

Material simplicity
This involves consuming fewer products and services, and tending to seek out products that are resource efficient, durable, and with a reduced ecological impact. Human scale
Following the principle of "small is beautiful" this favors working and living environments that are smaller, simpler and less centralized. Self-determination
This means to meet one's needs, or even to influence what those needs might be, through a reduced reliance on large commercial businesses, or even large public-sector organizations. Ecological awareness
People can change their behavior through marketing campaigns to encourage recycling and reducing  emissions and the adoption of conservation of resources and reduction of waste in order to protect the environment. Personal growth
This emphasizes satisfaction through experiences and development of personal abilities instead of through commercially provided consumption experiences. Many of the key traits of voluntary simplification have been exhibited in a less extreme, but more widespread way, through the phenomenon of "downshifting." Downshifting involves a change of lifestyle and consumption patterns that exchange a relatively highly paid/lower stress but more rewarding, and shifting to a lower level of material consumption but a higher level of quality of life and personal satisfaction. Sustainable consumption choices

All types of consumption are not equally important in terms of their sustainability impacts. The European Environmental Impact of Product Project provides a rigorous analysis of research into the environmental impact of products consumed by households. The project's input/output-based methodology assesses 255 domestic product types against a wide range of environmental impacts. It concludes that 70–80% of total impacts relate to food and drink consumption; housing (including domestic energy use); and transport (including commuting, leisure, and holiday travel). Ideally, all aspects of our consumption behaviors and production systems will become oriented toward sustainability, but initially significant progress would be achieved through the following:

 Sustainable food and drink consumption choices—Consumption level that are more conducive to health; a reduced consumption of meat products due to their contribution to climate change; choosing organically produced and locally sourced, seasoned produce; and greater composting of biodegradable food waste
 Sustainable housing consumption choices—More emphasis on purchasing homes constructed using sustainable materials and choosing and creating homes with high levels of insulation and energy efficiency. This also involves energy usage within the home based on sustainable energy source, and the avoidance of energy waste while living in the home (e.g. through energy-efficient refrigerators and energy saving bulbs). Sustainable travel behavior—Reducing the amount of travel (e.g. through home-working or teleconference service) or finding alternative transport means for journeys, such as cycling for leisure rather than driving. Seeking tourism offerings that try to protect the global and local environment and also the cultures within tourism destinations. Sustainable choices and motivational imbalance 
Individuals may experience motivational imbalance in which they believe a particular choice has positive personal outcomes but is subject to disapproval by important  or that the choice does not comply with their moral standards. Motivational imbalance can generate further ramifications on consumer sustainable choices. Toward behavior change

Behavior change in consumption is a guiding principle for sustainable development policy. However, switching unsustainable consumer behaviors to sustainable ones is far from straightforward. Individual behaviors are rooted in social and institutional contexts. We are influenced by what others around us say and do and by institutional rules. We have been already locked into unsustainable behaviors regardless of our intentions. Sustainable consumption choices are influenced by habit and routine. Habits can be thought of as procedural strategies to reduce the cognitive effort associated with making choices, particularly in situations that are relatively stable. They allow us to perform routine actions with a minimum of deliberation and often only limited awareness. Evidence suggests that habit is a crucial component in a wide variety of environmentally-significant activities: travel behavior, shopping patterns, household chores, waste disposal, leisure activities, and even personal hygiene. Habits are formed through repetition and reinforcement. Andersen (1982) identifies three stages in the formation of a new habit:
 The declarative stage involves information processing relating to a particular choice or action. At this stage the attitudinal and affective responses to this information are both important. The information challenges the existing choice, but at this stage does not actually change (e.g.) coffee-buying behavior. In the knowledge compilation stage, however, this information is converted into a new routine by exercising a different choice in practice. When the action itself is associated with a clear positive reinforcement, and repeated over time, a "cognitive script" is developed which enables one to repeat the same action in similar circumstances with very little cognitive effort. This final procedural stage locks into a new habit. At this stage, the behavior is more or less automatized and bypasses rational deliberation almost completely. In many cases, people appear to be locked into behaviors and behavioral patterns that resist change. In fact, they change continually and sometimes radically in a short period. The uptake of smart phones, widescreen plasma TVs, standby modes in electronic appliances, patterns of holiday travel and travel behavior: these are examples of technological and behavioral change that have occurred in only a decade. These sorts of changes are a kind of "creeping evolution" of social and technological norms. Individuals alter their behaviors and sometimes individual behavior initiates new social trends. At some level, individuals find themselves responding to societal and technological changes that are initiated elsewhere. Policies to encourage pro-environmental and pro-social consumer behaviors can be informed by understanding of the dimensions of and possibilities for behavioral change. Consumption is a holistic process, part of a broader consumer lifestyle, that is strongly influenced by the social context in which it takes place. Individual changes in purchasing behavior can contribute to progress toward sustainability, but progress also depends on supports from deeper changes occurring within consumer lifestyle and throughout society. There are now many  that support consumers in making their lifestyles more sustainable. See also
 Consumer behavior
 Sustainability
 Sustainable development
 Sustainability marketing
 Sustainable transport
 Efficient energy use
 Environmental impact
 Behavioral pattern

References

Consumer
Ethical consumerism