=Paper=
{{Paper
|id=Vol-1416/Session2Paper
|storemode=property
|title=Evidencing Sustainability Design through Examples
|pdfUrl=https://ceur-ws.org/Vol-1416/Session2Paper3.pdf
|volume=Vol-1416
|dblpUrl=https://dblp.org/rec/conf/re/ChitchyanBDPPV15
}}
==Evidencing Sustainability Design through Examples==
https://ceur-ws.org/Vol-1416/Session2Paper3.pdf
Evidencing Sustainability Design through Examples
Ruzanna Chitchyan Stefanie Betz Leticia Duboc
University of Leicester Karlsruhe Institute for Technology State University of Rio de Janeiro
Leicester, UK Karlsruhe, Germany Rio de Janeiro, Brazil
rc256@leicester.ac.uk stefanie.betz@kit.edu leticia@ime.uerj.br
Birgit Penzenstadler Christophe Ponsard Colin C. Venters
California State University Long Beach CETIC Research Center University of Huddersfield
California, USA Charleroi, Belgium Huddersfield, UK
birgit.penzenstadler@csulb.edu christophe.ponsard@cetic.be c.venters@hud.ac.uk
Abstract—Significant research has recently been undertaken • positively contribute to the personal well-being and sense
within the Requirements Engineering (RE) community towards of worth of its users (human sustainability);
understanding, integrating, and evaluating sustainability con- • positively contribute to cohesion and trust in the commu-
cerns in software systems. However, there still is no single point
of reference for either RE researchers or practitioners where nity of its users (social sustainability);
the work on sustainability is gathered and exemplified. It is the • support continued economic prosperity of its situated
aim of this paper to become such a reference point. Here we business (economic sustainability).
review the current work on RE and Sustainability, and gather
In this paper we have collated a number of techniques that
both the set of available approaches and demonstrative examples
on how each of the RE activities - from feasibility study to aim to strengthen the above outlined sustainability aspects
requirements management - can be undertaken with explicit throughout the requirements engineering process. While the
support for sustainability. This paper aims to serve as a starting presented collection of techniques and approaches is not com-
point for RE researchers and practitioners who wish to start prehensive, it does provide a good and encompassing overview
to positively contribute to sustainability of the socio-technical
of the major body of work related to requirements engineering
systems via RE research or practice.
Index Terms—Sustainability, sustainability design, require- activities for sustainability. The sources used for this paper
ments engineering, example have been taken from two recent systematic literature reviews
on software engineering and sustainability [1], [2] and the
latest work presented at RE4SuSy 2014 workshop [3].
I. I NTRODUCTION
The collected work is discussed and illustrated through two
Recently the Requirements Engineering (RE) research com- running examples from industry. We use the same example
munity has brought forward a number of methods, techniques systems for illustrating the use of different techniques, ex-
and approaches for systematically engineering sustainability plaining their application, and highlighting the peculiarities
of software systems and their situated contexts through re- that handling sustainability concerns could cause throughout
quirements engineering activities. Yet, there is still a shortage RE. Such an illustrative reference is crucial for convincing the
of reported case studies and examples on application of these practitioners of the validity of proposed methods and research
techniques, and where available, such reports tend to focus on results, as well as for helping the researchers to place their
a single RE activity. As a result, those wishing to engage with work within the current related work.
the research and practice of sustainability engineering through Outline: After introducing the illustrative examples: the
RE lack a single integrated view on the current state of art and DriveNow car sharing example and the ONE nursing system,
practice. The aim of this paper is to address this omission, and we go through all major activities in RE (from feasibility study
provide an integrated perspective on current techniques and to requirements management) and describe how these can be
approaches in RE for sustainability design. undertaken while taking sustainability into consideration, and
Here sustainability is defined as the ability of a system to illustrate how this was done in the two respective example
endure and prosper, thus, such a system will: studies. Then we provide brief review of related work for each
• be technically sound and adaptable (technical aspect of of the activities from the available research literature.
sustainability);
II. OVERVIEW OF THE K EY E XAMPLES
• positively contribute to its natural environment, or, at
the very least, actively minimize its negative impact DriveNow is a car sharing platform from BMW Munich,
(environmental sustainability); currently offering its services in four countries. The business
Copyright c 2015 for this paper by its authors. Copying permitted for private and academic purposes.
model is commercial car sharing for registered users with
flexible drop-off points for the vehicles on public parking lots.
The car sharing system is composed of a web application for
registration, reservation and billing, a car fleet maintained by
a service partner where each car is equipped with a meter
and a transponder, and a central database. In exchange for a
one-time fee, members of the program can use DriveNow cars
whenever needed. The nearest car can be located and reserved
though an online application or via phone. Once reserved,
the car is held free of charge for 15 minutes. Members only
pay for the time they used the car, not needing to inform
in advance about when they will need it for. At the end of
a booking, the car can be dropped anywhere in a specified
business area. Members can also choose the car model they
want, incur no extra fuel costs, and park for free within city
limits. DriveNow is an interesting example as it can show “a
positive contribution towards sustainability and environmental
protection” [4]. It is also highly dependent on technology,
including the development of the infrastructure and of the
diverse platforms that allow providers, partners and users to
interact with the system.
The ONE is a public institution run by the Belgian govern-
ment that supports children’s development from birth. Most
services offered by ONE are free of charge. The institution is Figure 1: Overview of the Organization
hierarchically structured in three layers (see Fig.1): A. Feasibility Study
• Layer one is the strategic management. Its main function 1) Overview of feasibility study and its relevance to sus-
is to develop birth and childhood policies. It also supports tainability: A feasibility study is carried out to check if it is
functions like finance, IT, and training. feasible to implement the desired system. During this activity
• In layer two is the decentralized operational management the project goals are defined and contradictions between these
which is located in six regions for coordinating the daily goals and the existing organizational values explored. In
field work. The main functions at this level are to support summary, a cost/benefit analysis is conducted on undertaking
children’s development within their families and social the project. Should these analysis indicate expected loss from
environment via prenatal consultations, medical and so- the project, the project will be canceled or substantially
cial children’s consultations, and outside of the family modified. The following issues need to be addressed during
environment via day care. Additionally, information for the feasibility study for a software system project:
future parents, training activities, and field studies is • Does the system contribute to overall objectives of the
provided. These main functions are supported by two key organization (which objectives, and how)? Are there any
roles: administrative referent and team coordinators. better alternative such that the system is not necessary?
• The third layer consists of teams executing the field work.
What problems will be addressed through the system?
The teams are composed of nurses working together • Can the system be implemented with given technology
with hired doctors. Each team is responsible for a small and within given cost? Is the organization able and willing
geographic location (for example a city district). to accept new/different technology?
The overview of the organization is provided in Fig. 1. • Can the system be integrated with other systems already
used in the company?
III. R EQUIREMENTS E NGINEERING WITH To answer these questions, the techniques used are, for
S USTAINABILITY C ONCERN : A WALKTHROUGH example, a quick SWOT (strengths, weaknesses, opportunities,
and threats) or TELOS (technical, economic, legal, opera-
In the following we briefly discuss each of the RE activities tional, schedule) or Business Model Canvas (BMC) analysis.
in turn (such as, feasibility study, stakeholder identification When sustainability is treated as an explicit concern in
etc.) along with very brief summaries of accepted RE tech- a feasibility study, the threats to and opportunities for all
niques for handling them. Relevance of sustainability to each aspects of sustainability of the organization and its situated
such activity is also commented upon. Then, using the above societies need to be considered. Similarly, so do the effects
discussed example cases, we outline how these activities can of the intended system (including its immediate, indirect, and
be handled while explicitly considering sustainability. Finally, systemic effects). Moreover, one needs to question if the
for each activity some additional related work is summarized. system goals align with the values of the intended customers,
users, and its situated societies. application is used on and the database servers for it (envi-
2) Illustrative Examples: DriveNow: To undertake the fea- ronment), or the change of work practice of the nurses, and
sibility study of the DriveNow system, the Business Model access to multilingual information and interpreter for non-
Canvas (BMC) technique is used. The BMC method creates a native speakers (individual).
one page graphical model that helps understand the structure The 2nd order effects include reduced emissions by the
of a business [5] by asking how an enterprise creates, delivers organisation due to reduced travel, increased number of fami-
and captures value. lies reached and children/prospective parents consulted, better
The BMC of the DriveNow system is shown in Fig.2. Since customized support for young families, reduced paper and
sustainability is considered as an explicit concern, such value printing materials use.
proposition of the business as the “Environmentally Sustain-
able Transportation” and “Integrated Transport” are identified, The systemic effects include, for instance, less congested
as this business “seeks to minimize the use of scarce resources health centres, decrease in personal stress in young families,
and maximize the use of more sustainable, low impact forms better children’s welfare and, in the end, a higher welfare of the
of travel” [6]. Education on Environmental Sustainability is society. Overall the system aligns well with the social values
also identified as a value provision stream: aiming to increase of the organisation as well as of its situated community.
uptake of this car sharing through educating customers on its 3) Other Work on Feasibility: Mahaux et al. [9] present
green credentials. Moreover, the value for human sustainability a study focused on minimising the impact of an event or-
aspect is supported via “Flexibility” of the customers as well ganization business (Yellow Events) on environmental sus-
as their fulfillment via “Driving Premium Cars”. tainability. Here the feasibility study is undertaken through
Whether the system has an explicit purpose for sustainabil- a “rich picture” style context model. This technique allowed
ity or not, it will cause some impact on sustainability. The to broaden the context considered for the system-to-be from
feasibility study should also consider the three-order effects of the product to the “environment-at-large”; the main actors and
the system [8]. For the DriveNow system, first-order effects are the material/information flows between actors were captured
caused by the resource consumption of the system itself (e.g., in the picture so that the impact of the business on envi-
the energy use). The second order effects arise from cars being ronmental sustainability can be visualized. This model was
shared, which decreases the overall consumption of resources used to identify opportunities to (1) minimize transportation
(e.g., no need to bring own car to the city and use extra of physical artifacts, (2) perform environmental calculations
gas, or use up parking space for long time). The third-order (e.g., carbon footprint), (3) check what has been tackled to
effects arise from system leading to reduction in the number lower the environmental impact, (4) help the environmental
of cars produced (as less cars are individually owned), greater specialists to assess current impact, and (5) communicate with
availability of parking spaces and, less congested streets. all stakeholders on improvements and alternatives.
ONE: The SWOT analysis for the ONE example high-
lighted that the main strength of a software system devel- Penzenstadler et al. [10] model a system for medication
opment is in improved access of the families with young adherence. The project followed the template according to
children to the relevant information and care services, as well business case method used at the Harvard Business School.
as in improved utilisation of the staff time. The system will First, the problem was defined, then the current situation was
also provide an opportunity to deliver the relevant information analyzed, which was followed by review of other solution
to young immigrant families with limited French/English options and cost-benefit analysis. The Business Case Analy-
language skills, as well as those with limited mobility. Main sis reveals the perspective of the stakeholders’ view on the
threats here are in missing out relevant requirements and view- problem that will be solved by the software system under
points which may jeopardies acceptance of the new system by development. In addition to the core elements (problem, anal-
the intended users. ysis, solutions, recommendations, and project description), the
Business Case Analysis for this requirement specification also
A number of sustainability goals have been identified for
included a section devoted to how the project will contribute
the ONE, such as:
to sustainability.
• Reduce need to travel for nurses
• Optimize format of consultations delivery (at fixed cen- 4) Summary Feasibility Study for RE with Sustainability
tres, periodic visits,via bus, at home); Concern: In summary, when undertaking a feasibility study,
• Ensure equal access for all, especially for the families one should consider the strength, opportunities, threats and
requiring more help and disabled; weaknesses that the system-to-be will pose to the full set of
• Reduce paper flow (electronic reporting, claims, statistics, sustainability dimensions, both through its direct use, and in
etc); the longer term, due to its enabling and systemic effects.
• Minimize language barriers (e.g. multilingual electronic
The same techniques and tools that are already used for
information, interpreters available at designated centers). feasibility analysis (SWOT, TELOS, BMC, rich picture, etc.)
For the ONE system, first-order effects arise, for instance, can be applied, as long as an explicit consideration is given
through the resource consumption via different devices the to each aspect of sustainability.
Figure 2: Business Model Canvas for DriveNow. Adapted from [7]
B. Stakeholder identification stakeholders. This can be done through establishing a role
of sustainability advocate, or including surrogate stakeholders
1) Overview of stakeholder identification and its relevance for marginalised or currently unavailable groups, such as a
to sustainability: Any (group of) individual(s), organization representative for future generations, or (at the very least)
or any entity that has interest or could be affected by the by referring to a domain expert on environmental standards,
software system-to-be is a stakeholder to that system. Since legislation, and regulations.
stakeholders are the primary source of requirements, collab- 2) Illustrative Examples: In the DriveNow system a num-
oration with the right set of stakeholders ensures that the ber of stakeholder groups were identified through tradi-
right requirements are identified and a useful system is imple- tional reference lists, goal analysis, and semi-structured inter-
mented. Traditionally, stakeholder identification is carried out views with known stakeholders. Additionally, a sustainability-
by selecting those entities who can be affected by or affect the specific stakeholder reference list was used [12] to find the
project. It can also be done through analysis of system goals missing sustainability stakeholders. The stakeholder model for
and strategies to fulfill these goals, or through analysis of roles the DriveNow system then included additional stakeholders
and interactions with the system, by using reference lists and that advocate sustainability or serve as domain experts for
models (such as Onion model), business process or rich picture life cycle analysis, environmental concerns and regulations,
analysis. Stakeholders can also be discovered by complying or social standards.
conventional theory of power, legitimacy and urgency [11]. For the ONE case, the existing organization was used to
In order to integrate the right sustainability requirements identify stakeholders, then business process modeling com-
into a given system, it is necessary to identify the appropriate menced from a process cartography, which became progres-
sources for such requirements, i.e., their stakeholders. While sively more detailed. After this, goal modeling (in connection
a good set of relevant sustainability requirements (e.g., those with a specific project) was applied - working with the known
related to human, social, or economic concerns) can be elicited key stakeholders to identify additional context specific stake-
from the traditional stakeholders, additional stakeholders are holders. A context diagram was used to picture information
necessary to present the otherwise silent interests, such as flow to identify current and future information producers and
environmental, or longer-term effects of the system on future consumers. The set of identified stakeholders also included
those that advocate social sustainability, childcare “concerns”, source of capitalizing on these opportunities and learning how
legislation for medical regulations, and social standards. The to counter their respective threats and weaknesses.
set of so identified stakeholders is shown in Fig.3 below. It
includes those that advocate social sustainability, childcare C. Requirements elicitation
“concerns”, legislation for medical regulations, and social
standards. 1) Overview of requirements elicitation and its relevance
3) Other Work on stakeholder identification: In Mahaux to sustainability: Requirements elicitation is the phase where
et al. [9], stakeholders for the Yellow Events were identified the stakeholders are interviewed, workshops are held to derive
using the Volere checklist [14], which already included the role usage scenarios, legal documents and standards are scanned
of “Environmental Specialist”. Additionally, authors defined for identifying constraints, and users are questioned with
“green thinking” and “anti-green thinking” clients and event regard to their objectives, wishes, and needs. There is a
participants. They suggest that most of the classical roles of plethora of methods for this task, from observation to creativity
stakeholders could have a “green” counterpart: green user, techniques, from storyboarding to analysing feature requests,
green client, green champion, and green finance specialist, etc. all with the objective to find out what the requirements for the
Penzenstadler et. al., [15] propose that stakeholders for system-to-be are.
sustainability can be found from four potential information Requirements elicitation is crucial for sustainability, as this
sources through the following simple approaches: is the task where the requirements engineer is actively in touch
1) Analyzing sustainability dimensions (e.g., via with all the stakeholders. If sustainability is acknowledged
goals/softgoals) for the given system to find roles as a key topic at this point in the conversation with the
of responsibility, and match them top-down to the stakeholders, it will be integrated into the requirements which
context of the system-to-be; will define what the system is and does. In short, if recognised
2) Instantiating generic lists of sustainability stakeholders and elicited as a set of necessary requirements, sustainability
for the concrete context; will be designed into the system.
3) Inspecting the context, understanding which concrete 2) Illustrative Examples: DriveNow: Elicitation of require-
roles are involved, and matching them bottom-up to the ments in DriveNow is supported via goal decomposition,
dimensions; where a goal is an objective the system under consideration
4) Iteratively analyzing and refining a generic sustainability should achieve. Here the objectives were elicited by consid-
model. ering the dimensions of sustainability and how they can be
In the system for medication adherence from Penzenstadler reflected with regard to the system. The set of original goals
et. al., [10], the stakeholders involved in the development was collected through a number of semi-formal interviews
and operation of the system are depicted, along with their with relevant stakeholders.
relations to the system with regards to contribution to all ONE: Goal-based elicitation technique was also utilised
five dimensions of sustainability through first, second, or third in case of ONE. Here functional and some quality goals
order effects. Ten stakeholder types are identified with some were identified from business process models with structured
directly interacting with the system, others taking on passive template requirements. Several of these goals (such as volume
role, but still affected by it. of information, paper flow, statistics, need for travel) directly
4) Summary of stakeholder identification for RE with Sus- reflect sustainability concerns. An excerpt for the ONE goal
tainability Concern: In order to represent sustainability re- model is shown in Figure 4 below. An example issue identified
quirements in the software systems, the relevant stakeholders via the this goal analysis is the substantial difference in work
must be identified and engaged into the RE process. This organisation, depending on geographical characteristics of the
can be done by complementing the traditional stakeholders locality. Thus, in cities, due to very high density of population,
with sustainability-specific ones through dedicated reference fixed deployment of nurses and doctors was preferred. In
lists for sustainability stakeholders (See Penzenstadler and rural areas with lower population density regular-frequency
Femmer [12] for a generic model for a generic list of sus- consultations (i.e. once a week) were chosen. In remote areas,
tainability stakeholders); business and operational context and with very low population density, a specially equipped bus was
goal analysis to identify relevant roles for the present and preferred where bus stops had to be customised to the current
future, or explicitly accounting for a “green” and “anti-green” demand.
counterparts of each identified stakeholder. Additionally, rel- 3) Other Work on requirements elicitation: In the Yellow
evant requirements will be elicited from more traditional Events study [9], author use and misuse case analysis [16] was
stakeholders, if they are made aware of sustainability and its used in elicitation of sustainability requirements. Since this
relevance to the specific stakeholders. It is evident that this study was focused on environmental sustainability, for each
process will lead to identification of many more stakeholders use case two questions were explicitly considered: What is
than “normal” with often new roles emerging to take respon- (or might be) harmful to the environment here? and How to
sibility for sustainability. Yet, if the costs and opportunities mitigate the identified harm? This resulted in identification of
of sustainability were considered in the project feasibility new use cases and/or modification of previously developed
study, the sustainability stakeholders will provide an invaluable ones.
Figure 3: Stakeholder model for the ONE. [13]
Figure 4: Partial goal model for the ONE system. Image from [13]
Penzenstadler et. al., [10] uses goal modelling to explore the system-to-be with respect to sustainability (either through
how the medication adherence system could improve the use/misuse cases, or through goal/anti-goal analysis), and fol-
five dimensions of sustainability, though human sustainability, lowing general “good practice” for sustainability requirements
aiming to improve patient’s well-being, which is the project’s identification. These practices include, for instance [18], a
central sustainability goal. few specific guidelines in requirements elicitation, such as:
Ahmed and Khaled [17] suggest to first raise awareness on (1) consider the estimated service time of the software and
a particular sustainability topic amongst the stakeholders, and expect to run it on legacy hardware to avoiding disposing
only then gather the sustainability requirements. They describe of existing hardware; (2) avoid using screens with bright
how such requirements have been collected from users and colors (as they consume more power) or colors that might
stakeholders after an informal workshop about alternative harm user eyes; (3) requirements should include switching
energy sources such as wind or solar energy. off the devices or operating in low power mode when not in
use; (4) avoid throwaway prototyping to elicit and understand
4) Summary of requirements elicitation for RE with Sus-
requirements, due to its unnecessary use of power, paper and
tainability Concern: Requirements elicitation can be accom-
custom hardware.
plished through interviews, observation, participatory work-
shops, as well as through goal elaboration, etc. The key guide- When working with goal models, a generic sustainability
line here is an explicit and deliberate treatment of sustainabil- goal model [12] can be instantiated for a specific system, if
ity as a topic of relevance to other areas of requirements. This sustainability is considered a major purpose of the system-to-
can be facilitated by either explicitly looking for misuse of be. When sustainability is one among a number of equally
important objectives, it is more appropriate to develop an In [27] a rich picture of the medication adherence system
overall goal model for the system and to detail the sub-model vision was used to take the input from the stakeholders and
for the objective of sustainability by using the sustainability goals and use this as a basis for the system use discussion.
dimensions and the generic sustainability model as a reference. This approach is used to give an overall view of the functions
of the system and how the stakeholders interact with it, as
D. Analysis and Negotiation well as for communication with a whole range of technical
1) Overview of analysis and negotiation and its relevance and non-technical stakeholders.
to sustainability: In this activity, the elicited requirements are Kocak [28] used the ANP based framework to prioritize
reviewed to uncover problems, such as inconsistencies and green software criteria in order to conduct trade-off analy-
incompleteness, and identify risks, such as safety hazards, sis. The framework can facilitate the identification of inter-
security threats, and development risks [19]. These problems dependencies between non-functional requirements and green
are then taken back to stakeholders be resolved through requirements, and their mutual influence as well as interactions
negotiation. A number of methods and techniques can be with the environmental sustainability concerns. The priority
used in this phase, such as checklists for identifying problems, weights, provided by the stakeholders for a number of at-
fault trees for risk analysis [20], qualitative and quantitative tributes, may be used to analyze trade-offs between conflicting
reasoning for evaluating multiple options [21], and analytic product quality and environmental requirements.
hierarchy process for requirements prioritization [22], among 4) Summary of analysis and negotiation for RE with Sus-
others. All these techniques could be used with sustainability tainability Concern: As with analysis and negotiation for
requirements as well, yet, a more desirable solution often is to other requirements, points of conflict, risks, or uncertainties
consider this as an opportunity for creative win-win solutions. identified for sustainability requirements need to be resolved.
Sustainability often is seen as competing with other system In many cases the established negotiation techniques (such as
goals [23] or as a trade-off between the present and the conflicts between goals, or AHP) can be used. However, one
future, as reinforced by the Brundtland report [24]. Analysing of the main peculiarities of sustainability requirements is their
and negotiating requirements with respect to sustainability, longer time span. In view of this, additional future forecasting
requires considering its various perspectives, stakeholders, and techniques, such as IMAGINE scenario development or use of
impact orders [8], as well as trying to find strategies that attend system vision can prove very useful.
both the present and future needs.
2) Illustrative Example: DriveNow: In this case [4] used E. Documentation
the IMAGINE scenario development technique [25] (adapted 1) Overview of documentation and its relevance to sustain-
from the sustainable development domain). Here sustainabil- ability: Requirement documentation is the process of speci-
ity indicators and their boundaries were elicited from stan- fying requirements and constraints clearly and as precisely as
dards, regulations and press publications, as well as from possible. A good documentation defines how software will
the stakeholders. The most relevant sustainability indicators interact with system hardware, other programs and human
were then chosen through stakeholder prioritization. Indicators users in a wide variety of real-world situations. Documentation
and boundaries were used to define minimum and maximum is used to establish an agreement between the customers
sustainable scenarios, and to analyse the current status of the and the suppliers on what the software product is to do,
system against a desired future one. These were represented for estimating costs and schedule, providing a baseline for
in the AMOEBA diagram shown in Fig.5. validation and verification as well as to support maintenance
ONE: For ONE, the negotiation centred around such ob- and future extension [29]. Documenting sustainability require-
stacles as specific hardware needs or legal signature require- ments is not much different form documenting other (quality)
ments preventing transformation of paper documents flow requirements. However, presently it may prove impossible to
into electronic versions. Negotiation involved a conversation provide a measurable and specific specification for a number
between several stakeholders with different goals and lead to of sustainability requirements (such as those related to so-
reviewing the current business processes, refactoring them, and cial sustainability or long-term human sustainability), as the
converging to a new set of processes. quantification frameworks for these are yet to be developed.
3) Other Work on analysis and negotiation: In the Yellow Where quantification is possible (e.g., environmental impact
Events system [9], the positive and negative goal contributions measured in in terms of CO2 emissions) documentation (as for
from the goal models were used as drivers for negotiation. any other requirements) should normally be completed using
The lower level goals were used to identify the list of impacts set templates, such as those provided by ISO standards [29]),
between goals as well as the possible resolution actions, and or templates for use cases [30], and Volere Shell [31].
compensation programs. 2) Illustrative Examples: DriveNow:
The work of Gu et. al., [26] uses a Green Strategy Model to In this study [7] the Volere Shell requirement specification
break “green goals” (i.e., those with ecological implications) template [31] was used to document system requirements; the
down into (a number of) “green actions”. This model can be environmental sustainability dimension was considered a non-
used for the sustainability goal elaboration and negotiation on functional requirement. The used template consists of parts
the actions to be taken in order to reach these goals. describing the requirement type, its brief description and a
Figure 5: AMOEBA diagram for the car sharing system (axes are selected sustainability indicators; shapes capture the current
goal scenario and the min and max sustainable boundaries). Image from [4]
rationale; it is also checked for representability, completeness, describe each actions in terms of different fields, such as type,
and concretization. short descriptions, long description in the spreadsheet. The
Further details on the documentation of DriveNow include objective of creating such a spreadsheet is to collect green
use case specifications [32], sustainable system vision, feature actions of each goal, and then share and communicate with
descriptions and purpose of the features, preconditions, and other application fields.
variations that enable users to carpool. In [27] a categorisation for sustainability requirements and
ONE: In case of ONE, the results of the analysis of business constraints is proposed that groups these into four categories:
processes, management processes, and support processes were process requirements, deployment requirements, system con-
documented in two,100 page specifications that adhered to straints, and quality requirements. Further concerns for the
a standardized template (based on the ARIS method) using system or the project may be managed in a risk list.
organizational diagrams as well as UML models. These also 4) Summary of documentation for RE with Sustainability
include use cases templates, process modeling in activity Concern: As with all documentation, the main consideration
diagrams, etc. Furthermore, the documents comprise a detailed when documenting sustainability requirements is in striking
description of the surrounding operational environment, i.e. the the right balance with detailed specification which avoids
systems that interact with the system-to-be through a variety duplication. Whichever technique is used for documentation,
of interfaces. the longer term consequences and the systemic nature of
3) Other Work on documentation: For Yellow Events [9], sustainability requirements must be considered. For instance,
a number of RE documents have been used, including rich- uses of systems that would arise after a period of system
content context diagram, use case diagram, goal models, exploitation could be considered, as is done with the system
template-based textual requirements specification as well as vision and IMAGINE techniques. Similarly, the cumulative
class diagrams, glossary, and business process models. Sus- effect of individual uses of the system must be reviewed, which
tainability requirements were documented in many of these. would lead to defining minimum and maximum operational
In work on the Green Strategy Model [26], it is suggested parameters for a given system and safe failover in case of
that domain experts should codify the green actions and under-use or overflow should be designed into the software.
F. Validation mental Protection Agency and a sustainability expert gave
1) Overview of validation and its relevance to sustainabil- their project an opportunity to validate goals and the relations
ity: Validation is an activity whereby previously elicited and between the goals and the five dimension of sustainability.
consolidated requirements (aggregated from elicitation, anal- 4) Summary of validation for RE with Sustainability Con-
ysis, negotiation, documentation) are fed back to the system cern: When undertaking validation of sustainability-related
stakeholders to make sure the requirements still corresponds requirements, one needs to ensure that all stakeholders con-
to stakeholder needs. This is because, given the changing (and cerned with the given sustainability requirement have a consis-
possibly iterative) requirements engineering process, these tent, shared view on its content and implications. The impor-
could have been substantially altered. tance of this point is demonstrated by the above discussed case
Validation is carried out through requirements walk- of ONE, where the initial agreement on sustainable service
throughs, inspections, and desk checks, as well as through delivery goal was found to imply very different implemen-
prototyping. This activity is particularly important to ensure tations depending on population density of a given location.
that the utility of the intended system in maximized. It is also Furthermore, given the fast changing notion of sustainability,
particularly relevant for sustainability requirements, given that it is likely that the understanding of such requirements will
sustainability goals often mandate engagement and coopera- evolve and change quite frequently, which will lead to change
tion of multiple stakeholders, and it is essential to ensure that of the system vision and IMAGINE scenarios, which were dis-
they all agree and remain committed to the same sustainability cussed previously for the DriveNow example. Thus, repeated
requirements. validation from multiple perspectives is advisable where ex-
2) Illustrative Examples: DriveNow: Validation for the ternal stakeholders (such as domain experts on environmental
car sharing system was mainly performed by presenting the or social sustainability) can also provide an invaluable input.
models developed in the previous stages to the main stake-
G. Management
holder from BMW, the project manager of the DriveNow.
There were two requirements meetings which were kicked 1) Overview of management and its relevance to sustain-
off with presentations by the BMW stakeholder, followed by ability: Requirements management is the activity focused on
long QA sessions with the requirements engineers. After the maintenance and control of requirements’ information of a
requirements analysis, specification and documentation in each software system for the duration of that system’ lifetime. It is
phase, there was a validation workshop with presentations by primarily concerned with change control, integrity preserva-
the requirements engineers and clarifying questions. tion, and traceability of requirements. This tends to be a rather
With respect to sustainability, the following steps were challenging task due to difficulties in maintaining consistency
taken: (1) to evaluate current status of the system and the and integrity within and between the continuously evolving
opportunities for improvements in each of the sustainability requirements. While this activity can, to some degree, be
indicators, and (2) plan corrective actions, in order to achieve supported with tools (such as DOORS or IBM Rational),
the desired system state. In particular, points that needed to be the maintenance process cannot be fully automated and is
improved for the DriveNow system were: the number of cars ultimately dependent on the consistency and commitment
to be saved (for the environmental perspective), the system and of the requirements engineering team. For sustainability
availability (for the technical perspective), and the market requirements such commitment will be even more important
acceptance (for the economical perspective). given that it is a very fast changing domain.
ONE: Validation at ONE was carried out iteratively and 2) Illustrative Examples: In the DriveNow project, require-
with different level of stakeholder participation: first by a ments were documented through a consistent template by all
requirements analyst with one of the stakeholder parties, then teams. Following the initial basic set of requirements, several
internally by the manager with the relevant doctors and nurses teams of requirements engineers developed specifications for
team, from which feedback was given to the requirements the best system extension in a competition. Consequently,
engineer, and, finally, with participation of all stakeholders they managed their requirements in a distributed way. Yet,
together. Through these activities, it was observed that the there was no central repository other than the final delivered
regional differences lead to very different perspective of specifications, or change and traceability management support.
some sustainability requirements. Thus permanent, static, fully In the ONE project, requirements were managed inside
equipped admission rooms were required in cities, but only the ARIS toolset. The project was aligned with a larger in-
regular visits or bus trips in rural areas; continuous internet house cartography method (called “GPS”) to collect the or-
connection and desktop-based applications were needed in per- ganisational structure, existing business processes, information
manent locations, but mobile devices and even simply phone- flows, and related IT applications. ARIS allowed to share items
based interaction was required for others. Thus, the validation across different models and to generate reports able to link
activities allowed to segregate locations-based variability in the goals and business processes. However there was no company
interpretations of sustainability goals (previously considered wide sustainability view explicitly encoded in the repository.
homogeneous for all), and to take respective design actions. 3) Other Work on management: In [33], a conceptual
3) Other Work on validation: In related work [10] Pen- reference model is developed for the development, usage and
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