The tetrahedron of sustainability design - a 3D framework for the
integral and interdisciplinary development of circular economy oriented
products
Authors: Stegmüller Sebastian , Braun Franziska 
Published: July 2023

Traditional product design follows three main directions that had to be
thought and planned in an integrated way: Desirability, feasibility, and
viability. Aspects from user research, technology development and business
models must be weighed against each other and to be optimized as holistic
concept. For future product design those three dimensions seems to be not
sufficient any more as the sustainable impact from products regarding their
production, usage and end of life, becomes an important factor in
development processes. The so-called circular economy, that describes the
goal of a most efficient use of resources and products in closed loops,
brings with it totally new requirements for products and their development.
Already the traditional innovation design should have been understood as a
joint task of market researchers, engineers, business planers and designers,
but the arising challenge of the development objectively sustainable
products needs that interdisciplinary thinking even more. New frameworks,
tools and method that allow the interdisciplinary exchange in an effective
way to enable the creation of joint visions and concepts are needed. While
the traditional three fields of product design as described by Tim Brown can
be showed in two-dimensional frameworks as three overlapping circles, the
addition of sustainability as fourth design field needs more complex
visualization that brings the different aspects in relation to each other.
For solving that task and for creating a new tool as core for
interdisciplinary, circular economy oriented design projects, we developed
and evaluated a three-dimensional framework – the tetrahedron of
sustainability design. The critical aspect of integrating the circular
economy as a decision parameter into innovation processes arises through the
facts that target conflicts will come up that can not be solved in an easy
way as product individual lifetimes must be taken into consideration.
Therefore, the main goal of the framework is to motivate discussions of
different disciplines and their decisions regarding to the effecting
influence on other design fields. It is created as tangible
three-dimensional object as anchor point for workshops and individual
considerations. The tetrahedron of sustainability designs shows the four
fields of future product design as equilateral pyramid with triangular
bases, with each design field representing one of the bases. The corners of
the pyramid, each closed by three of the design fields, are defined as four
main levers of sustainable product concepts. At the top of the pyramid, the
central value proposition that can be described as a set of abstract value
elements that should be fulfilled by the product, must be thought by
reflecting the customers (desirability), the business model (viability) as
well as the sustainability effects (integrity). While those first three
design fields open up the space of conceptualization, the field at the
basement of the pyramid represents the technological realization
(feasibility) of the products. It is enclosed by the following corners: The
R-Strategies define how circular economy effect should be created, e.g. by
recycling, reusing of parts or rethinking of the product functions. Beneath
the technical realization. This corner is additionally affected by the
understanding of the customer and the sustainability effects. The next
corner, the life cycle consideration, describes how a product is produced,
used, maintained and how its end of life can be shaped. As well as the
technical realization, the design fields of the business model and the
sustainability effects are relevant to that corner. The last corner is
defined as the degree of servitization what is based on the understanding of
innovations as solution-oriented product-service-systems. While the physical
parts are described by the technical realization, the business model and the
customer wishes affect what product aspects can be realized as additional
value-added service or by innovative ownership-models. As last part of the
framework six edges have been defined, each located between two design
fields and two corners. Those six edges are formulated as concrete decision
points and hints for the design process. Starting from the value proposition
corner, every three edges of the space of conceptualization lead to one of
the tree corners that surround the basement of realization and are
influencing the determination of the abstract product concept. Against that,
the three edges of the base of realization are formulated as guiding
principles for the physical product design. The whole framework, its
elements and the way of usage will be explained an defined more in detail in
the paper. Furthermore, the framework will be shown and evaluated on an
exemplary design project. As example the concrete design project of an
electric scooter for young urban generations will be introduced and
reflected regarding of the aspects of the framework.