Product lifetime

Product lifetimes represent an important area of enquiry with regards to product design, the circular economy[1] and sustainable development.[2] This is because products, with the materials involved in their design, production, distribution, use and disposal (across their life cycle), embody carbon due to the energy involved in these processes.[3] Therefore, if product lifetimes can be extended, the use of energy, embodied in carbon, can be reduced and progress can be made towards reducing greenhouse gas emissions: Bocken et al.[4] term this "Slowing resource loops" (309, their emphasis). In addition, excessive waste generation has been attributed to short-lived goods and a throwaway society.[5]

Discussion of product lifetimes stretches beyond consideration of the service life concept. For example, the consideration of a product's service life refers to the time a product is in use from when it is sold to when it is discarded (see [6]). However, Murakami et al.[7] identify that, firstly, there are different ways service life can be defined (e.g. total lifespan, domestic service lifespan, extended service lifespan by domestic reuse etc.), and secondly, there are aspects of product lifetimes which are not captured by service life (e.g. residential time, service lifespan of parts, production span etc.).

This article examines how product lifetimes are defined in the academic literature and discusses how product lifetimes can be measured. A distinction is made between the definition and measurement of actual and expected product lifetimes.

Defining product lifetimes

Definitions of product lifetimes vary depending on what aspects those conducting research are interested in. Generally, actual product lifetimes refer to the actual time that a product exists in a particular state.[7] In contrast, expected product lifetimes refer to users' expectations for the lifetime of a product.[8] Additionally, actual and expected product lifetimes are influenced by durability and longevity; these concepts are briefly outlined below.

Durability is described by Cooper[6] as "the ability of a product to perform its required function over a lengthy period under normal use conditions of use without excessive expenditure on maintenance or repair" (p. 5). In contrast, longevity encompasses more than just the material properties of the product.[2] Cooper[2] notes that user behaviour, and broader social and cultural trends play important roles in the product's longevity. The paragraphs below outline the definitions of actual and expected product lifetimes.

Actual product lifetimes

Exhaustive work has been undertaken by Murakami et al.[7] and Oguchi et al.[9] and to outline several definitions and discuss methods for identifying actual product lifetimes. Murkami et al.[7] identify the following overarching concepts in product lifetime definitions which are discussed below: Age, Residential time, Service life, Possession span and Duration of use.

Age

A product's age is the time from when the product was created to either the present or "the time of interest" (:[7] 600) for the researchers.

Residential time

Residential time is considered to be time in which a product, its constituent materials and parts, exists in society.[7] Residential time includes the time in which a product may be broken and/ or discarded.[7]

Service life

Main article: Service life

According to Murkami et al.,[7] the Service life of a product refers to the duration of time for which products (e.g. Service lifespan/ Total lifespan, Extended service lifespan by repair, Extended service lifespan by domestic reuse) and parts (e.g. Service lifespan of parts, Extended service lifespan of parts by reuse) continue to work and can be used.

Possession span

The possession span is the period of time that a user has possession of the product.[7]

Duration of use

The duration of use indicates how long a user uses the product for.[7] Murkami et al.[7] distinguish duration of use from Service life by noting that duration of use is measured for a specific user, whereas Service life describes the total in-service use of the product for all its users (accounting for transfers of ownership e.g. reuse). Additionally, possession span is distinguished from duration of use, as possession span includes "dead storage" (:[7] 601) time, where a product is owned by a user but not in use (i.e. in storage).

Expected product lifetimes

A conference paper by Oguchi et al.[8] sought to identify and test differences in definitions of product lifetime expectations. Oguchi et al.[8] illustrated that previous research into expected product lifetimes has been inconsistent in its use of the term expected product lifetimes. For example, Cooper[10] enquires about "reasonable" expected lifetimes, while Brook Lyndhurst[11][12] discusses "normal" expected lifetimes. Wieser et al.[13] identified the tension between everyday expectations and desires, distinguishing between these expectations in his study of 21 products. In addition, earlier work by Tasaki et al.[14] and more recent work by WRAP[15] have asked users to report both how long they have owned an item for, and how long they expect to use the item for in future: WRAP[15] term this "active use". Building on these previous studies (described above), Oguchi et al.[8] identified and tested three distinct definitions of expected product lifetimes, these are outlined below.

Intended lifetime

Oguchi et al.[8] define the intended lifetime as the length of time for which a user intends to use the product in question.

Ideal lifetime

The ideal length of time for which a user expects their product to last. Oguchi et al.[8] describe this as "the highest preference of consumers".

Predicted lifetime

The realist prediction by the user of how long a product will last. The user is thought to make this prediction based on their previous experiences and "other relevant factors" (Oguhci et al.[8]).

Measuring product lifetimes

Academic enquiry into the product lifetimes of electrical and electronic equipment was undertaken in 2000 by Cooper and Mayers[16] who conducted household interviews and focus groups to establish the age at discard (actual product lifetime) and expected lifetimes for 17 products. Since this study, work has been undertaken by other academics into measuring actual and expected product lifetimes; the methods employed are outlined below.

Actual product lifetimes

Actual product lifetimes can be measured using a variety of methods which include: product testing, discard surveys, user interviews and modelling. These are discussed below.

Product testing

Products can be tested under laboratory conditions to assess their lifetime under different conditions of use.[2]

Discard surveys

Oguchi et al.[9] identify that surveys of waste treatment and recycling facilities can provide information on the age of the appliance at break or discard. Identifying information such as the product serial and/ or batch number can be used to find out a date of manufacturer from which the age of the appliance at break or discard can be calculated.

User interviews

Cooper and Mayers[16] conducted household interviews to establish the age of 17 electrical and electronic items at discard and break. However it has been noted that user interviews are subject to the accuracy of memory, and that reviews of products which have failed in the past only provides information on "a historical situation" (:[2] p. 10), not taking into account the features and lifetime of extant products.

Modelling

Product lifetimes can be modelled using extant data from surveys with the application of probability and other statistical concepts (e.g. distributions).[9][17] One of the earliest attempts to estimate product lifetimes was undertaken by Pennock and Jaeger[18] who utilised actuarial methods to measure the Service life of household goods for one owner. In the 1990s, Bayus[19] modelled car replacement rates and Bayus and Gupta[20] evaluated the user decision making process and factors around replacement car purchases.[20] In 2010, Oguchi et al.[9] proposed modelling product lifetimes factoring the total number of products shipped and discarded in a year. Oguchi et al.[9] outlined a series of equations which represent lifespan distributions for a given product at a particular point in time.

Expected product lifetimes

Expected product lifetimes are measured at the individual level using survey methods and collectively using focus groups. With the exception of Oguchi et al.[8] and Wieser et al.,[13] many studies into expected product lifetimes have not distinguished between the different definitions (outlined above). The methods for measuring expected product lifetimes are outlined below.

Survey methods

Survey methods into expected product lifetimes encompass online questionnaires,[8][13] household[16] and telephone[21] interviews. These studies asked individual participants to report their expectations for product lifetimes in units of time. Survey methods (such as Oguchi et al.[8]) can also use Likert items to evaluate if current products meet users expectations with regards to durability and longevity.

Focus groups

Focus groups can be convened where participants take part in discussions to reach a group consensus on product lifetime expectations.[12]

References

  1. ↑ Montalvo, C., Peck, D. and Rietveld, E. (2016). A longer lifetime for products: benefits for consumers and companies (PDF). Brussels: European Parliament's Committee on Internal Market and Consumer Protection (IMCO).
  2. 1 2 3 4 5 Cooper, T (2010). "The significance of product longevity". In Cooper, T. Longer Lasting Products: alternatives to the throwaway society. Farnham: Gower. pp. 3–36.
  3. ↑ Norman, J.B., Serrenho, A.C., Cooper, S.J.G., Owen, A., Sakai, M., Scott, K., Brockway, P.E., Cooper, S., Giesekam, J., Salvia, G., Cullen, J.M., Barrett, J.R., Cooper, T., Hammond, G.P. and Allwood, J.M. (2016). A whole system analysis of how industrial energy and material demand reduction can contribute to a low carbon future for the UK. (PDF). CIE-MAP.
  4. ↑ Bocken, Nancy M. P.; Pauw, Ingrid de; Bakker, Conny; Grinten, Bram van der. "Product design and business model strategies for a circular economy". Journal of Industrial and Production Engineering. 33 (5): 308–320. doi:10.1080/21681015.2016.1172124. ISSN 2168-1015.
  5. ↑ Packard, Vance (1963). The Waste Makers. Harmondsworth: Penguin.
  6. 1 2 Cooper, T. (1994). Beyond recycling: the longer life option. London: New Economics Foundation.
  7. 1 2 3 4 5 6 7 8 9 10 11 12 Murakami, Shinsuke; Oguchi, Masahiro; Tasaki, Tomohiro; Daigo, Ichiro; Hashimoto, Seiji (2010-08-01). "Lifespan of Commodities, Part I". Journal of Industrial Ecology. 14 (4): 598–612. doi:10.1111/j.1530-9290.2010.00250.x. ISSN 1530-9290.
  8. 1 2 3 4 5 6 7 8 9 10 Oguchi, M., Tasaki, T., Daigo, I., Cooper, T., Cole, C. and Gnanapragasam, A. (2016). "Consumers' expectations for product lifetimes of consumer durables.". Electronics Goes Green 2016+ Conference. Berlin.
  9. 1 2 3 4 5 Oguchi, Masahiro; Murakami, Shinsuke; Tasaki, Tomohiro; Daigo, Ichiro; Hashimoto, Seiji (2010-08-01). "Lifespan of Commodities, Part II". Journal of Industrial Ecology. 14 (4): 613–626. doi:10.1111/j.1530-9290.2010.00251.x. ISSN 1530-9290.
  10. ↑ Cooper, Tim. "Inadequate Life? Evidence of Consumer Attitudes to Product Obsolescence". Journal of Consumer Policy. 27 (4): 421–449. doi:10.1007/s10603-004-2284-6. ISSN 0168-7034.
  11. ↑ Brook Lyndhurst (2011). Public understanding of product lifetimes and durability (1). London: Department for Environment, Food and Rural Affairs.
  12. 1 2 Cox, Jayne; Griffith, Sarah; Giorgi, Sara; King, Geoff (2013-10-01). "Consumer understanding of product lifetimes". Resources, Conservation and Recycling. SI: Resourceful Behaviours. 79: 21–29. doi:10.1016/j.resconrec.2013.05.003.
  13. 1 2 3 Wieser, H., Tröger, N. and Hübner, R. "The consumers' desired and expected product lifetimes". Product Lifetimes and The Environment. Nottingham: Nottingham Trent University. pp. 388–393.
  14. ↑ 智宏, 田崎; 淳, 寺園; 祐一, 森口 (2004-01-01). "長期使用とリュース促進のための家電製品・パソコンの廃棄行動実態とその行動要因の調査". 廃棄物学会論文誌. 15 (4): 310–319. doi:10.3985/jswme.15.310.
  15. 1 2 Langley, E., Durkacz, S. and Tanase, S. (2013). Clothing longevity and measuring active use. Banbury: WRAP.
  16. 1 2 3 Cooper, T. and Mayers, K. (2000). Prospects for household appliances. Sheffield: Sheffield Hallam University for E-SCOPE.
  17. ↑ Oguchi, M. (2015). "Methodologies for estimating actual lifetime distribution of products". Product Lifetimes and The Environment. Nottingham: Nottingham Trent University. pp. 388–393.
  18. ↑ Pennock, Jean L.; Jaeger, Carol M. (1957-06-01). "Estimating the Service Life of Household Goods by Actuarial Methods". Journal of the American Statistical Association. 52 (278): 175–185. doi:10.1080/01621459.1957.10501377. ISSN 0162-1459.
  19. ↑ Bayus, Barry L. (1991-01-01). "The Consumer Durable Replacement Buyer". Journal of Marketing. 55 (1): 42–51. doi:10.2307/1252202.
  20. 1 2 Bayus, Barry L.; Gupta, Sachin (1992-08-01). "An empirical analysis of consumer durable replacement intentions". International Journal of Research in Marketing. 9 (3): 257–267. doi:10.1016/0167-8116(92)90021-C.
  21. ↑ Echegaray, Fabián (2016-10-15). "Consumers' reactions to product obsolescence in emerging markets: the case of Brazil". Journal of Cleaner Production. Special Volume: Transitions to Sustainable Consumption and Production in Cities. 134, Part A: 191–203. doi:10.1016/j.jclepro.2015.08.119.
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