Many people have a preconceived notion that
“sustainment” and “sustainability” only refer to environmental sustainability,
which is unfortunate. Sustainment and
sustainability are concepts that are much older and broader than just the
environmental context that the popular media most often relates them to.
The origin of the word sustain is the Latin word sustenare, which means “to hold up” or “to support”. The modern use of the word sustain is to keeping something going or
to extend its duration, [1], where the most common synonym for sustain is maintain. It is not uncommon
for sustain and maintain to be interchangeably used, however, maintenance usually
refers to activities that are targeted at correcting problems, while sustainment
is a more general term referring to the management of system evolution.
The concept of sustainability is connected to nearly every discipline
[2], e.g., environmental sustainability, business or corporate sustainability
and technology sustainment, however, in this blog we are interested in
technology sustainment. Although sustainability and sustainment are
closely related in a semantic sense, environmental sustainability organizations
almost never refer to what they are doing as sustainment or sustainment
engineering. However, organizations that
maintain systems (sustainment organizations) use both sustainment and
sustainability to describe what they do.
Technology sustainment refers to all activities necessary
to [2]: a) keep an existing system operational so that it can successfully
complete its intended purpose; b) continue to manufacture and install versions
of the system that satisfy the original requirements; and c) manufacture and
install revised versions of the system that satisfy evolving requirements.
Sustainment Definition
The most widely circulated definition of
sustainability is attributed to the Brundtland Report [3], which is often paraphrased as
“development that meets the needs of present generations without compromising
the ability of future generations to meet their own needs.” This definition was
created in the context of environmental sustainability, however, it is useful and
applicable for defining all types of sustainability. For example, for technology sustainment, “present
and future generations” in the Brundtland definition can be interpreted as the
users and maintainers of a system. Unfortunately, the definition of sustainability has
been customized by many organizations to serve as a means to an end, and in
some cases it has been abused to serve special interests and marketing.
A good general definition of sustainment is [4]: “development, production,
operation, management, and end-of-life of systems that maximizes the
availability of goods and services while minimizing their footprint”. In this case the terms in the definition
mean:
- “footprint” could represent any kind of impact that is relevant to the system’s stakeholders, e.g., cost (economics), human health, energy required, environmental, and/or other resource consumption (water, materials, labor, expertise, etc.)
- “availability” represents the fraction of time that a good or service is in the right state, supported by the right resources, and in the right place when the customer requires it
- “customer” could be an individual, a company, a city, a geographic region, a specific segment of the population, etc.
Note that this definition is consistent with both
environmental and technology sustainment concerns.
Sustainment-Dominated Systems
A sustainment-dominated system is defined as a system for
which the lifetime footprint significantly exceeds the footprint associated
with making it [2]. Where "footprint" has the same definition as above. Defining sustainment-dominated
systems provides the opportunity to make a distinction between high-volume, low
cost consumer products and more complex, higher-cost systems such as airplanes,
infrastructure, and institutions. Non-sustainment-dominated products, which
tend to be high-volume products, have relatively little investment in
sustainment activities and the total time period associated with the product is
short (short manufacturing cycle, short field life). Alternatively, sustainment-dominated
products, which tend to be relatively low-volume expensive systems, have large
sustainment costs and long manufacturing and/or field lives (see my "More Than Acquisition Costs - F-35" blog post in December 2016).
[1] Sutton,
P. (2004). What is sustainability? Eingana,
27(1), pp. 4-9.
[2] Sandborn,
P. and Myers, J. (2008). Designing engineering systems for sustainability, in Handbook
of Performability Engineering, K.B. Misra, Editor, pp. 81-103 (Springer,
London).
[3] Brundtland Commission (1987). Our Common Future, World
Commission on Environment and Development.
[4] Sandborn, P. (2017). Cost Analysis of Electronic Systems, 2nd edition, World Scientific.
