What is Sustainable Software?

In software engineering the term "sustainability" traditionally refers to "maintenance" and is still widely used in this manner. This is the more incomprehensible as "sustainability" is  well accepted as enduring mankind’s existence in a world of limited, steadily depleting, and nearly exhausted natural resources since the early nineties. The UN defined sustainable development recursively as a development that "meets the needs of the present without compromising the ability of future generations to meet their own needs."1
Beginning with the Green IT hype in the last few years, environmental sustainability attained a lot of importance in the area of ICT. The potential of Green IT is expressed in two sub-concepts: Green in IT and Green by IT2.
  • Green in IT means being environmentally sustainable in ICT (aka direct impacts3,4)
  • Green by IT means: being environmentally sustainable by using ICT in order to gain higher energy and resource savings in its application areas (aka enabling impacts, mostly smart technologies3,4)
Besides the environmental aspects, ICT especially plays a significant role in the social and economic development of developing and emerging countries as it improves communication, education, and access to information, which opens new social and economic perspectives and possibilities. Of course, this is also valid for already developed countries, but there the access to ICT is usually very easy and common today.
Putting all together, each pillar of sustainable development, economy, society, and environment should be addressed by Sustainable Software. Taina5 defined some basic requirements for green software, which we consider to be wide enough to apply also to Sustainable Software:
"We require green software to fulfill three abstract requirements:
  1. The required software engineering processes of software development, maintenance, and disposal must save resources and reduce waste.
  2. Software execution must save resources and reduce waste.
  3. Software must support sustainable development."5:23-24
Just before Taina, Dick et al.6 published a definition that is very similar to Taina’s requirements:
"Sustainable Software is software, whose direct and indirect negative impacts on economy, society, human beings, and environment that result from development, deployment, and usage of the software are minimal and/or which has a positive effect on sustainable development."6:250, 7:296
Comparing both definitions, it turns out that Taina’s requirements are narrower than the definition of Dick et al., because Taina requires that software supports sustainable development, whereas Dick et al. leave this aspect as optional.
As an effect, it is probably not possible with Taina’s requirements to label a general purpose software, e.g. a word processor or enterprise resource planning system that is especially optimized to have a low environmental footprint, as Sustainable Software, because you may use it for activities that have either a positive or a negative effect on sustainable development. In such a case, the third requirement cannot be fulfilled in general.
Which one of the definitions will make the running in the discussions of the green/sustainable software community cannot be estimated at this moment. Probably this issue will be answered with the introduction of a green software label.
Until then, you are free to choose a definition that fits your needs best!

  1. Report of the World Commission on Environment and Development. Our common future. New York (1987). http://www.un.org/ga/search/view_doc.asp?symbol=A/42/427
  2. Heng, S., Klusmann, B., K├Ânig, F.: Green IT. More than a passing fad! Deutsche Bank Research, Frankfurt am Main (2010). http://www.dbresearch.de/PROD/DBR_INTERNET_DE-PROD/PROD0000000000268157/Green+IT%3A+More+than+a+passing+fad%21.pdf
  3. OECD Information Technology Outlook 2010. OECD Publishing, Paris (2010). http://www.oecd.org/sti/ito
  4. Greener and Smarter. ICTs the Environment and Climate Change. OECD Report. OECD Publishing, Paris (2010). http://www.oecd.org/dataoecd/27/12/45983022.pdf
  5. Taina, J.: Good, Bad, and Beautiful Software - In Search of Green Software Quality Factors. CEPIS UPGRADE, volume XII, pp. 22–27 (2011). http://www.cepis.org/upgrade/media/taina_2011_41.pdf
  6. Dick, M., Naumann, S., Kuhn, N.: A Model and Selected Instances of Green and Sustainable Software. In: Berleur, J., Hercheui, M.D., Hilty, L.M. (eds.) What Kind of Information Society? Governance, Virtuality, Surveillance, Sustainability, Resilience. 9th IFIP TC 9 International Conference, HCC9 2010 and 1st IFIP TC 11 International Conference, CIP 2010, Held as Part of WCC 2010, Brisbane, Australia, September 20-23, 2010. Proceedings, pp. 248–259. Springer, Berlin, Heidelberg (2010). doi:/10.1007/978-3-642-15479-9_24
  7. Naumann, S., Dick, M., Kern, E., Johann, T.: The GREENSOFT Model: A Reference Model for Green and Sustainable Software and its Engineering. SUSCOM, volume 1, issue 4, pp. 294–304 (2011). doi:10.1016/j.suscom.2011.06.004