This first lesson of the course reviews some important definitions related to sustainability and sustainable development. We start with very general concepts and then narrow it down to specific principles and how they apply to technologies. Understanding the role of technology in sustainable society is central to this course. As we go from one topic to another, we will always return to the practical question: Is this particular method, product, or design good for our future or should we better look for alternatives? This lesson sets the context. We get introduced to the principles of sustainable design and sustainable engineering and see how they can direct our thinking, innovation, and eventually lifestyle. This lesson also includes introduction to the systems analysis, which becomes an effective tool in understanding interactions between environmental, economic, and social factors in sustainable development.

Learning Objectives

By the end of this lesson, you should be able to:

• understand definitions and principles of sustainable development;
• understand how these principles apply to design and engineering;
• recall the basics of the systems analysis and apply this approach to a simple system as an example;
• identify the role of technology in sustainability framework.

Readings

You will be asked to read the following items throughout your lesson. Look for these readings in the required reading boxes throughout the lesson pages.

Questions?

If you have any questions while working through this Lesson, please post them to our Message Board forum in Canvas. You can use that space any time to chat about course topics or to ask questions. While you are there, please feel free to post your own responses if you are able to help out a classmate.

Sustainability as a Term

The term sustainability has a multidisciplinary use and meaning. In dictionaries, sustainability is typically described by many sources as a capability of a system to endure and maintain itself. Various disciplines may apply this term differently.

In history of humankind, the concept of sustainability was connected to human-dominated ecological systems from the earliest civilizations to the present. A particular society might experience a local growth and developmental success, which may be followed by crises that were either resolved, resulting in sustainability, or not resolved, leading to decline.

In ecology, the word sustainability characterizes the ability of biological systems to remain healthy, diverse, and productive over time. Long-lived and healthy wetlands and forests are examples of sustainable biological systems.

Since the 1980s, sustainability as a term has been used more in the sense of human sustainability on planet Earth, and this leads us to the concept of sustainable development, which is defined by the Brundtland Commission of the United Nations (March 20, 1987) as follows:

Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

The following video will further elaborate on this definition and will give a few examples on its meaning.

Video: What is Sustainability (9:43)

With human decision-making involved, sustainability attains a significant ethical aspect and transforms the social paradigm on success, growth, profit, standards of living. This reevaluation requires a broader and more synergistic overview of many components of anthropological ecosystems, including technology.

The topic of sustainable development gained enough importance in the last few decades of the 20th century to become a central discussion point at the 1987 General Assembly of United Nations (UN). Concerned by the quick deterioration of the human environment, uneven development, poverty, population growth, extreme pressure on planet's land, water, forest, and other natural resources, UN issued an urgent call to the World Commission on Environment and Development to formulate a "global agenda for change" [UN, 1987]. The result of this action was the report "Our Common Future," which further served as the global guideline for the world's nations in formulating their political and economic agenda. This document is almost 40 years old now and was followed up by a long array of actions and movements in subsequent years. But let us go back for a little bit and see how it all started.

The original 1987 Report prepared by the World Commission on Environment and Development is a big document (over 300 pages), so I do not advise you to read it all right away. The following reading (about 16 pages) is Chapter 2 of the report, which talks specifically about the concept of sustainable development. So, some of the terms, definitions, and perspectives outlined there will be especially useful for our further work and discussions in this course. So, here is your first reading assignment:

Three Pillars of Sustainability

Sustainable development involves environmental, economic, and social aspects. For a particular process to be sustainable, it should not cause irreversible change to the environment, should be economically viable, and should benefit society. An illustration of the interplay among these three spheres is schematically provided in Figure 1.1. Sustainability is represented as the synergy between society, economics, and environment. The environmental aspects include use of natural resources, pollution prevention, biodiversity, and ecological health. The social aspects include standards of living, availability of education and jobs, and equal opportunities for all members of society. The economic factors are drivers for growth, profit, reducing costs, investments into research and development, etc. There are more factors that will affect sustainability of a social system - these few are listed as examples.

Interaction of social and economic spheres results in the formulation of combined socio-economic aspects. Those are, for instance, business ethics, fair trade, and worker's benefits. At the same time, a combination of economic and environmental interests facilitate increasing energy efficiency, the development of renewable fuels green technologies, and also the creation of special incentives and subsidies for environmentally sound businesses. Intersection of social and environmental spheres lead to creation of conservation and environmental protection policies, establishment of environmental justice, and global stewardship for sustainable use of natural resources. This framework is in some way a simplification, but it proved to be helpful in identifying key areas of impact and set the basis for objective analysis. Further in this course particular processes and technologies will be often evaluated in terms of social, economic, and environmental impacts, although we should understand that those three pillars are never fully isolated from one another.

Figure 1.1. Interplay of the environmental, economic, and social aspects of sustainable development.

Credit: Mark Fedkin. Adopted from the University of Michigan Sustainability Assessment [Rodriguez et al., 2002]

Dimensions of Sustainability

The above-mentioned three pillars of sustainability are very common terms in the literature, media, and communications and convey a simple idea to grasp. However, the interconnections between these three pillars are not at all simple and can actually occur in different planes of thinking. Three fundamental meanings or dimensions of sustainability were defined by Christian Becker in his book "Sustainability Ethics and Sustainability Research" as continuance, orientation, and relationships. To understand what those dimensions exactly mean, please refer to the following reading. As discussed in this chapter, the multi-dimensional nature of sustainability is something that often results in confusion and miscommunication between different entities and spheres involved. For example, an environmentalist, economist, and politician can discuss sustainability as a project goal but actually have three different goals in mind. So, new project developers in the sustainability era should certainly seek to broaden their perspective and, at the same time, develop sufficient depth in articulation of their sustainability vision. Enjoy the reading:

If you completed the short reflection note in the box above - good job! You will find it very beneficial to write down some of your own thoughts while you are still fresh off your reading.

United Nations’ 17 Sustainable Development Goals (SDG)

In September 2015, the UN General Assembly adopted the 2030 Agenda for Sustainable Development, which converged in setting 17 sustainable development goals. These goals link the conceptual understanding of sustainability to specific focus areas, where actions are needed.

These goals became the common framework for governments and organizations developing sustainability plans, assessing new initiatives and emerging technologies, and tracking progress. So, it would be wrong not to include them here:

UN Sustainable Development Goals 

Credit: n.a. “UN Sustainable Development Goals” UN. 

I do have to note that most of these goals still sound very general and would require specific measures (or metrics) to assess their achievement.

Further in this course, we will occasionally revisit the definitions and interpretations of sustainability. This is one of the concepts that sets context for our main focus in this course - technology role and assessment. In the next section of this lesson, we will start seeing how technology is sometimes considered the cornerstone of the society development and survival. While some theories heavily bet on technology as the universal solution to society's ever-growing needs, others are much more skeptical. So, prepare for some controversy.

Steady State Economy

Herman E. Daly (1938-2022), a renowned expert in ecological economics, who has been a longtime proponent of the concept of sustainable steady state economy (as opposed to economic growth), formulated several basic rules for a sustainable society, known as Daly Rules:

1. Renewable resources - e.g., groundwater, biomass - must be used no faster than the rate at which they regenerate.
2. Nonrenewable resources - e.g., minerals, fossil fuels - must be used no faster than renewable substitutes for them can be put into place.
3. Pollution and wastes must be emitted no faster than natural systems can absorb them, recycle them, or render them harmless.

Sustainable steady state theory states that human societies can grow to a special state, where resource supply and consumption are balanced. This should be considered a sustainable steady state. After this balance point has been reached, only refinement of societies (via better use of available resources through more efficient technologies) instead of growth (increase in supply and consumption of resources) should be pursued.

According to Daly’s theory, economic growth cannot be maintained forever because the planet and its resources have finite physical dimensions and capacity:

“If resources could be created out of nothing, and wastes could be annihilated into nothing, then we could have an ever-growing resource throughput by which to fuel the continuous growth of the economy. But the first law of thermodynamics says NO. Or if we could just recycle the same matter and energy through the economy faster and faster we could keep growth going. The circular flow diagram of all economics principles texts unfortunately comes very close to affirming this. But the second law of thermodynamics says NO.” [Daly, 2009]

But is reaching a sustainable steady state in fact realistic and practically achievable? Daly argues that there is a practical alternative to the economic growth paradigm. That would rely on a number of critical economic steps and policies. Daly's measures may seem controversial and somewhat radical at a national or international scale, but they touch an important scaling question: how large can a system be and keep its potential for sustainability?

If you are interested in learning more about Dr. Daly's views on economic growth and a steady state economy, check out his interview below.

Video: "Herman Daly on the Economy and the Environment" (51:06)

Oscillating Steady State

Contrary to the steady-state paradigm, an alternative view expressed in works by Howard T. Odum and collaborators (for example “Environmental Accounting: Emergy and Decision Making” 1995) considers the whole planet a self-organizing system, where storages of resources are continuously depleted and replaced at different rates, and matter recycling and reorganization is driven by solar, geothermal, and gravitational energies. It is hypothesized that one of the possible reasons for oscillating systems to be preferable over steady state systems is that they are governed by the system feedback to changing environmental conditions or depletion of one or other storage. The system should be able to tune its performance according to the changing environment.

As the diagram in Figure 1.2. illustrates, net primary production and storage of resources (expressed as Quantity Q) develop faster than consumer assets (expressed as Quantity C) until the system reaches a threshold where autocatalytic and higher order pathways are accelerated. At the threshold, consumer assets show a sudden increase at the expense of the environmental storage (consumer pulse). As the resources are used up quickly, consumer assets drop, allowing a new cycle of building resource storage to begin. In the case of global economy, the storages can be represented, for example, by oil, minerals, topsoil, and other slowly renewable resources, while the consumer assets are human economies and civilization. The theory presumes that this kind of pulsation can be sustained over time.

Figure 1.2. Pulsing growth paradigm.

Credit: Odum, 1988

Anthropogenic Ecology Theory

Some contemporary scientists find Daly's arguments overly pessimistic. For example, Erle Ellis, an associate professor of geography and environmental systems at the University of Maryland, Baltimore County, and a visiting associate professor at Harvard’s Graduate School of Design, argues that over the course of the anthropogenic history, humans have almost never relied simply on the carrying capacity of natural ecosystems, but rather created specially engineered ecosystems. Such artificial eco-niches utilize intelligent approaches and technologies for extracting more usable resource from the nature. So, essentially, Ellis infers, there is no problem of limiting carrying capacity due to creative transformative powers of humankind.

Within the anthropogenic ecology theory, the emergence of new sociocultural niches in human society is represented as a novel evolutionary process in the Earth system. These niches are the result of re-shaping the biosphere into new organizational level which allows virtually unlimited upscaling of societies through culturally mediated changes.

To better understand and to analyze the dynamics of feedback and oscillations within socio-ecological systems, it would be useful for us to look at the basics of the systems thinking approach. This thinking framework is especially important to sustainability science, because it allows tracking logical interconnections between natural factors, economic factors, social motifs. More details are given further in Sections 1.5-1.8 of this lesson.

The next question for us to explore is how the meanings of sustainability extend into technical spheres, specifically engineering, design, and technology development.

The term design is normally referred to the "way of doing things or making things" in various areas of human activity. Design is always driven by a specific objective, such as making the product or system most efficient, or most profitable, or most aesthetically impressive, etc. Such objectives can be drastically polar and to reach them, designing phase may require change of thinking and high level of creativity. So, what is sustainable design?

This concept was largely advocated by William McDonough, an American designer, architect, author, and thought leader, who espouses a message that we can design materials, systems, companies, products, buildings, and communities that can continuously improve over time.

"If design is the first signal of human intention, our intention today can be to love all ten billion people who will live on our planet by 2050. We can do this. If we imagine and embrace our cities as part of the same organism as the countryside, the rivers and the oceans, then we can celebrate ourselves, all species and the natural systems we support and that support us. This is our design assignment. If we are principled and have positive goals, we can rise to this occasion. It will take us all; it will take forever—that is the point." (McDonough, 1992)

The concept of sustainable design is supplied with some lively illustrations in McDonough's TED Talk

Watch this video: William McDonough's TED Talk (19:46)

McDonough crafted sustainable design principles for Expo 2000, The World’s Fair, which became known as "The Hannover Principles: Design for Sustainability." This document has wide philosophical and ethical dimensions and should be seen as a living document committed to the transformation and growth in the understanding of our interdependence with nature and future generations.

Book cover of the Hannover Principles

Credit: McDonough, 1992

THE HANNOVER PRINCIPLES

1. "Insist on rights of humanity and nature to coexist in a healthy, supportive, diverse and sustainable condition.
2. Recognize interdependence. The elements of human design interact with and depend upon the natural world, with broad and diverse implications at every scale. Expand design considerations to recognizing even distant effects.
3. Respect relationships between spirit and matter. Consider all aspects of human settlement including community, dwelling, industry and trade in terms of existing and evolving connections between spiritual and material consciousness.
4. Accept responsibility for the consequences of design decisions upon human well-being, the viability of natural systems and their right to coexist.
5. Create safe objects of long-term value. Do not burden future generations with requirements for maintenance or vigilant administration of potential danger due to the careless creation of products, processes, or standards.
6. Eliminate the concept of waste. Evaluate and optimize the full lifecycle of products and processes, to approach the state of natural systems, in which there is no waste.
7. Rely on natural energy flows. Human designs should, like the living world, derive their creative forces from perpetual solar income. Incorporate this energy efficiently and safely for responsible use.
8. Understand the limitations of design. No human creation lasts forever and design does not solve all problems. Those who create and plan should practice humility in the face of nature. Treat nature as a model and mentor, not as an inconvenience to be evaded or controlled.
9. Seek constant improvement by the sharing of knowledge. Encourage direct and open communication between colleagues, patrons, manufacturers and users to link long term sustainable considerations with ethical responsibility, and reestablish the integral relationship between natural processes and human activity."

It is a philosophy that can be applied in the fields of architecture, landscape architecture, urban design, urban planning, engineering, graphic design, industrial design, interior design, fashion design, human-computer interaction, and many other areas depending on modern technologies.

In the consideration of the above principles, a strong emphasis is put on #6 [waste elimination], since it perhaps has the most profound impact on environment and human health as well as contains possible solutions for smart use and reuse of limited natural resources. A good waste prevention strategy would require that everything brought into a facility or process be recycled for reuse or recycled back into the environment through biodegradation. This would mean a greater reliance on natural materials or products that are compatible with the environment. Any resource-related development is going to have two basic sources of solid waste — materials purchased and used by the facility and those brought into the facility by visitors. The following are some waste prevention strategies that apply to both, although different approaches will be needed for implementation:

• Low-impact materials: Choose non-toxic, sustainably produced or recycled materials which require little energy to process.
• Energy efficiency: Use manufacturing processes and produce products which require less energy.
• Emotionally Durable Design: Reduce consumption and waste of resources by increasing the durability of relationships between people and products, through design.
• Design for reuse and recycling: "Products, processes, and systems should be designed for performance in a commercial 'afterlife'."
• Biomimicry: "redesigning industrial systems on biological lines ... enabling the constant reuse of materials in continuous closed cycles..."
• Service substitution: Shift the mode of consumption from personal ownership of products to provision of services which provide similar functions, e.g., from a private automobile to a carsharing service. Such a system promotes minimal resource use per unit of consumption (e.g., per trip driven).
• Renewability: Materials should come from nearby (local or bioregional), sustainably managed renewable sources that can be composted when their usefulness has been exhausted.

Here are some of the examples how design approaches attempt to promote the sustainability principles:

Emotionally Durable Design

 

The 2CV Chronicles Project

Credit: Liz Nehdi / The 2CV Chronicles Project

The concept and philosophy of Emotionally Durable Design was pioneered by Jonathan Chapman, Professor of the University of Brighton (UK). According to this philosophy, increasing the resilience of relationships established between consumers and products reduces the consumption and waste of natural resources. Chapman states that "the process of consumption is, and has always been, motivated by complex emotional drivers, and is about far more than just the mindless purchasing (and discarding) of newer and shinier things". For example, these couple of images illustrate personalized design of products, when in addition to their normal function, the objects also help the owner to make a statement or express their style of life. To this end, 'emotional durability' can be achieved through consideration of the following five elements:

CAPTION_CONTENTS.

Credit: Making It Magazine

• Narrative: How users share a unique personal history with the product.
• Consciousness: How the product is perceived as autonomous and in possession of its own free will.
• Attachment: Can a user be made to feel a strong emotional connection to a product?
• Fiction: The product inspires interactions and connections beyond just the physical relationship.
• Surface: How the product ages and develops character through time and use.

As a strategic approach, "emotionally durable design provides a useful language to describe the contemporary relevance of designing responsible, well-made, tactile products which the user can get to know and assign value to in the long-term."

Biomimicry

Morpho Butterfly

Credit: CREDIT_CONTENTS

Biomimicry is the imitation of the models, systems, and elements of nature in design, engineering, and science, primarily for finding new solutions to scientific or technological challenges. Biomimicry has given rise to new technologies created from biologically inspired engineering at both the macro scale and nanoscale levels. In fact, humans have been looking at nature for answers to both complex and simple problems throughout world history. Nature has solved many of today's engineering problems, such as hydrophobicity, wind resistance, self-assembly, and harnessing solar energy through the evolutionary mechanics of selective advantages. Here are several examples (out of many) showing the use of biological subjects as models in technology.

Because natural systems are a priori sustainable, designs observed in the nature can be viewed as prototypes of smart technologies for potential anthropogenic sustainability systems.

1. A. The morpho butterfly (shown in the image above from Wikipedia) gains its color due to the special structural orientation of scale in its wings. Incident light is reflected at specific wavelengths to create vibrant colors due to multilayer interference, diffraction, thin film interference, and scattering properties. Now, some companies (Qualcomm) use this principle in manufacturing colored displays at much lower power consumption (as compared to production of dyes).

CAPTION_CONTENTS.

Credit: http://en.wikipedia.org

1. B. Researchers studied the termite's ability to maintain virtually constant temperature and humidity in their termite mounds in Africa despite outside temperatures that vary from 1.5 °C to 40 °C (35 °F to 104 °F). Researchers initially scanned a termite mound and created 3-D images of the mound structure, which revealed construction that can influence human building design. The Eastgate Centre, a mid-rise office complex in Harare, Zimbabwe (image on the left), stays cool without air conditioning and uses only 10% of the energy of a conventional building of its size (Source: Biomimicry).
2. C. Holistic planned grazing, using fencing and/or herders, seeks to restore grasslands by carefully planning movements of large herds of livestock to mimic the vast herds found in nature, where grazing animals are kept concentrated by pack predators and must move on after eating, trampling, and manuring an area, returning only after it has fully recovered. Developed by Allan Savory, this method of biomimetic grazing holds tremendous potential in building soil, increasing biodiversity, reversing desertification, and mitigating global warming, similar to what occurred during the past 40 million years as the expansion of grass-grazer ecosystems built deep grassland soils, sequestering carbon and cooling the planet (Source: Biomimicry).
3. Paper wasps' nests are made out of cellulose (or chewed-up wood) and wasp saliva. The wasp uses saliva that has a lot of protein in it, and that protein mixed with the cellulose creates a water-insoluble but also waterproof covering. It is interesting that in rainy environments, wasps are found to use more protein in their saliva in order to make the nest more waterproof. And because protein is quite expensive from a wasp’s standpoint because they have to go get more insects to get more protein, they are only going to use it if they really need it. So, if this is in a dry environment or protected from overhead, they are not using as much protein. This idea can be borrowed to make non-toxic, waterproof paper, or other biodegradable materials (Source: Biomimicry Case Examples)

"Engineering in context, engineering with a conscience, engineering for a finite planet and the indefinite future"

Sustainable engineering should be based on principles that support sustainable development, as defined in the upper sections of this lesson. Engineering forms an interface between the design (i.e., the idea how to provide a sustainable solution to a technical problem) and implementation and production. In case of technology development, engineering phase is linked to almost every level of technology readiness spectrum. Sustainable engineering principles should be contemplated and applied early to ensure that technology development and scale-up follow the environmentally benign route. It will be hard to turn back to redo and redesign things from later stages! In that sense, the sustainable engineering principles should be taken into account in decision making for both research and industrial projects, as well as in policy making and decisions regarding funding of technological research.

There have been multiple attempts by academic and industrial institutions to formulate sustainable engineering principles. All of them fall within the triangle with Environmental, Social, and Economic values as cornerstones. The overarching goal is to generate a balanced solution to any engineering problem. If an engineering project benefits one of these three aspects but ignores the others, we have a lopsided system which creates tension, instability, and new problems in the long run.

Here are some of the aspects that differentiate the traditional and sustainable approaches in engineering:

The diagram in Figure 1.3. presents a consolidated framework for sustainable engineering principles, which are in part adopted from the work of Gagnon and co-authors "Sustainable development in engineering: a review of principles and definition of a conceptual framework" (2008) and from the green engineering principles established by Sundestin Conference (2003).

Figure 1.3. Classification of sustainable engineering principles versus environmental, social, and economic criteria.

Click for text description. This will expand to provide more information.

Figure 1.3 text description

Various principles of sustainable engineering are placed on the perimeter of the triangle. On the triangle's bottom edge are the Society pole (left) and the Economy pole (right). From left to right, the four principles shown are as follows:

• Offer individuals and communities the opportunity to increase their capabilities.
• Know your "needs" and "wants." Put primary focus on achieving needs of larger number of individuals.
• Allocate in a fair manner benefits and costs related to economic activity and public policies.
• Maintain a positive genuine long term investment considering all types of capital.

On the triangle's left edge are the Society pole (bottom) and the Environment pole (top). From bottom to top, the four principles shown are as follows:

• Ensure that all material and energy inputs and outputs are as inherently safe and benign as possible.
• Look beyond your own locality and the immediate future.
• Preserve access to exosystems services essential to health and wellbeing.
• Preserve biodiversity and respect all life forms, regardless of how useful they are to humankind.

On the triangle's right edge are the Environment pole (top) and the Economy pole (bottom). From top to bottom, the four principles shown are as follows:

• Stay within ecosystem's carrying capacity in terms of resource development and waste assimilation.
• Develop closed cycles of operation and consumption to minimize waste.
• Offset the use of non-renewable resources by investments in renewable substitutes.
• Stimulate innovation to facilitate the adaption of more efficient and greener technologies.

The principles shown at the center of the triangle are as follows:

• Engineering processes holistically, use system analysis, and integrate environmental impact assessment tools.
• Seek stakeholder involvement while respecting local subsidiarity and cultures.
• Internalize all costs within the value of goods and services (polluters must pay).

Credit: based on concepts from Gagnon et al., 2008

Figure 1.3 lists the various principles of sustainable engineering versus environmental, social, and economic poles. Some of these principles clearly gravitate towards one of the corners of this triangle and thus address particularly societal, environmental, or economic concern. But some others, which are placed along the sides of the triangle, have connections to two of the poles of the diagram and address both societal and economic, or both economic and environmental concerns in some proportion. Those principles placed in the center of the diagram combine all three aspects of sustainability to a certain degree and hence their implementation would benefit all societal, environmental, and economic stakeholders. We should not consider this collection of principles set in stone. Many sources and organizations build on the existing documents and provide their own visions. I invite you to reflect on this diagram and provide your comments for making it more complete and more concrete for our future consideration.

These principles can be viewed as guidelines for a specific engineering project. We are going to look at a specific example where the engineering solution was able to address the need and benefit sustainability, not sacrificing one for the other.

Jubilee River Case Study

This example presents a success story about how sustainable engineering has been applied to address a critical community need. The need is always placed in the center of an engineering project and directs design efforts. In this case, the need was a flood prevention system. While the traditional approach of creating the concrete trapezoidal channel would address the need perfectly and cost-effectively, it would have environmental and social trade-offs. For example, construction would destroy or disturb natural vegetation and wildlife, cause high soil erosion, create a large amount of construction waste, and have a negative aesthetic impact.

The alternative approach was to convert these problematic trade-offs into benefits. That required some additional investment and a wider range of collaboration among civil engineers, ecologists, and landscape architects. The result was creation of a permanent, landscaped, ecologically compatible relief channel, with amenities and environmental features of a natural river (Figure 1.5), which eventually became an asset to the community and increased rather than decreased the quality of life.

Figure 1.4. Current state of the Jubilee River landscape.

Credit: David Short (via Flickr)

To summarize the information in this reading, please provide answers to the following questions:

The goal of an engineering project can be to create a system, a device, a process, or any other outcome that would provide a certain service or benefit to society. One of the important outcomes of an engineering project is the creation of technology.

Role of Technology

Role of technology can be actually viewed as the interface that provides connection of an idea realized through design and engineering effort with practical and consumable outcomes, such as products or services. The latter would affect and shape societal lifestyle over time. Figure 1.4 presents a hierarchical view of these connections in the sustainability context.

Figure 1.5. Hierarchy of sustainability guidelines and role of technologies emphasized.

Credit: Mark Fedkin © Penn State is licensed under CC BY-NC-SA 4.0

Figure 1.5 shows how the most general sustainability principles are narrowed down to specific material outcomes for the society. The principles of sustainability guide the sustainable design, the process of thinking. This stage determines how things are supposed to be made and how they will function over their whole lifecycle. Further down the funnel, the sustainable engineering stage deals with technical implementation of ideas. Sometimes it is not an easy process, and some aspects of design may be changed or compromised. When eventually the design and engineering routes practically converge, we may have a technology created. Technology provides processes and products. Only then the benefits of new ideas and new engineering developments become available to society. Here we can identify the role of technology as some sort of portal through which the established principles of sustainable design and engineering may affect people’s lifestyle. Because of people's strong dependence on multiple technologies, those become the factors that can facilitate change in society and can even become tools of manipulation and initiation of global trends.

This way of thinking emphasizes the importance of technologies in the whole hierarchy of causes and factors that regulate the sustainable development.

To build the contextual framework for applying the sustainability principles, we need to develop some background in systems. We often hear terms like “systems thinking” or “systems approach”. Or in some cases, to initiate a sustainable and long-lasting change, we need to change the “system” rather than trying to change the final result. The material in this section is the tip of a bigger iceberg – system analysis is applicable to a very broad scope of problems, from economics to climatology, and it very often becomes a powerful tool in strategic decision-making. In this course, the systems approach will be essential when we consider technology trends and implementation in a broader societal context, where multiple forces – economic, environmental, political, educational, and psychological - come into play. It is not about simple ‘yes/no’ questions – it is our way to explore the complexity and possibly to find answers to ‘why’ questions for the most part. Let us start with some definitions.

Are we dealing with a system?

A system is an interconnected set of elements that is organized in a way that achieves a purpose. Three distinct entities of any system are elements, interconnections, and purpose (or function). These ensure system’s integrity and often determine such system’s properties and behaviors as development, resiliency, self-organization, self-repair, and eventually - sustainability. You can tell that you are dealing with a system, not a random collection of components, if you can identify the mutual impacts between the components and observe the outcome or behavior over time that is different from the outcomes or behavior of the separate components on their own.

For example, a forest is a system consisting of trees, soil, multiple species of flora and fauna – all of which are interconnected via food chains, nutrient flows, energy exchange, and many other chemical and physical processes. Its function is to provide environment and nutrition for sustaining living organisms and also to produce oxygen via photosynthesis. If one takes an element out of the system (e.g., taking a certain tree species and planting it in an isolated environment, or taking an animal and placing it in a zoo), those elements would behave differently, the same as the system deprived of a certain element will be affected and will react to the change.

In a social context, for example, a village is also a system, not a simple aggregation of houses and people. Houses may be connected through the utility networks, people are connected through trade, collaboration, and social relationships. Disruption of life and function on one side of the village would cause system’s reaction and change.

In the technical world, system functions can be even more obvious, since many engineering systems are designed by people for a specific purpose. Thus, a power plant system has a purpose to produce electric power and distribute it to a community or facility. It consists of equipment, workers, transportation means, fuel stocks, etc., all of which are interconnected in power production cycle.

System elements

Next, we are going to cover three types of elements that will be used in system analysis further on. Specifically, those include: stocks, factors, and decision points.

Figure 1.6. Notations of three types of elements included in system analysis.

Credit: Mark Fedkin © Penn State is licensed under CC BY-NC-SA 4.0

Stocks

Stocks can be represented by sort of matter, commodity, or good. Stocks are cumulative and are characterized by measurable amount. They can accumulate (increase), deplete (decrease), or stay steady. In system diagrams, we are going to show each stocks as a box.

Examples of stocks:

• Money on the bank account
• Number of trees in the forest
• Number of people living in a town
• Amount of food stored for winter
• Amount of energy stored or generated at a power plant

Very often, the stability of a system depends on the maintenance of its stocks. If the bank account is stable or growing, we believe that whatever system maintains it is working well. If there is no decline in tree population, we assume the forest is healthy.

Factors

Factors can be represented by processes, flows, phenomena, actions, and even feelings that have influence within a system. Factors are measurable, but not necessarily cumulative, and are typically characterized by rates or intensity of process rather than countable amounts. Rates are important since they will affect the variations of stocks. In system diagrams, we are going to include factors in ovals.

Examples of factors:

• Rate of tree growth in the forest
• Air temperature at the forest location
• Electricity price at local market
• Solar irradiance at a specific location
• Number of cups of coffee you drink per day

Almost anything can be included as a factor in a system, as long as its variation influences the system state or other elements.

Decision Points

Decision points are very special elements that represent deliberate controls of the system by humans. Humans make a variety of decisions, which may or may not be dictated by the system behavior, and can be based on knowledge, personal choices, feelings, political views, conscience, etc.

Examples of decision points:

• Adopting a policy
• Decision to invest in growth of business (or not)
• Decision to restrict construction or practice
• Decision whether the stock level is dangerously low

In system diagrams, we are going to depict decision points as diamonds.

There may be other elements that are distinguished in various system models. But for the sake of simplicity, we are going to mainly operate with the three elements described above.

System Connections

In a system, elements are interconnected and may influence one another. If connections are not identified, the collection of elements you have, may not be a system after all. The following types of connections are most important.

Positive Coupling

Positive coupling is when an increase in A results in an increase in B.

• Increase in sunlight leads to higher solar panel output
• Increase in coal combustion results in growth of CO2 emissions
• More chickens, more eggs

This will also work backward: Fewer chickens, fewer eggs, etc.

This type of connection can be shown with a regular arrow:

Figure 1.7. Example of a positive coupling.

Credit: Mark Fedkin © Penn State is licensed under CC BY-NC-SA 4.0

Negative Coupling

Negative coupling is when an increase in A results in a decrease in B.

• Increase in mileage decreases car’s service life
• Amount of food consumed decreases the feel of hunger
• Increase in spending decreases amount of money in the bank account

And again, vice versa, in case of a negative coupling, a decrease in A would increase B. You can check if this opposite connectivity works with the above examples (it is not always the case).

This type of connection can be shown with a circular arrow:

Figure 1.8. Example of a negative coupling.

Credit: Mark Fedkin © Penn State is licensed under CC BY-NC-SA 4.0

It is important to understand that the connection drawn from A to B is not at all identical to the connection from B to A. We cannot simply put the arrow both ways automatically. For one of the example of positive coupling, we said: “increase in sunlight leads to higher solar panel output”. Obviously, the reversed relationship will not work: increase in solar panel output will NOT increase the amount of sunlight, and in fact it will not affect the amount of sunlight at all. So, before drawing the arrow from B to A, we need to think first if there is actually a reverse impact, and if yes, then whether it is a positive or negative coupling.

Feedback Loops

Feedbacks are very interesting properties of systems. Feedbacks are higher in the hierarchy of causal connections than couplings. While a coupling simply denotes the influence of one system element on another, feedbacks go further to show how those other elements impact the original cause. A feedback is always a loop, and therefore must contain at least two, but often more couplings in it. Here are some examples.

• More chickens, more eggs. But if we have eggs that can hatch and produce more chickens, we have a reverse connection: more eggs, more chickens. This is feedback.

Figure 1.9. Example of a feedback loop – chicken and egg problem.

Credit: Mark Fedkin © Penn State is licensed under CC BY-NC-SA 4.0

• More stuff bought, less money left. That is a negative coupling. However, the less money is available, the less stuff we can further buy. This is a positive connection on the way back. And again, using these two couplings, we can identify a feedback loop between these two elements.

Figure 1.10. Example of a feedback loop – shopping dilemma.

Credit: Mark Fedkin © Penn State is licensed under CC BY-NC-SA 4.0

We can see from these two simple examples that feedback always “backfires” to the original element and affects any other element in the loop via circular impact.

Feedbacks are interesting internal mechanisms that can either stabilize or destabilize the system. In the next section of this lesson, we will consider two main feedback types – positive and negative – and see what effects they can cause.

Positive feedbacks

Imagine that you have some money in your bank account. The more money you have, the more interest you earn annually. That interest is added to your account balance, which earns you even more interest. So we can definitely see how A affects B, and B affects A in this case:

Figure 1.11. Positive feedback loop consisting of two stocks and two positive couplings.

Credit: Mark Fedkin

As the two positive couplings act in circles within this loop, your account balance keeps growing. Such a feedback loop is called positive or reinforcing (here is the “+” sign in the loop), because the system sort of feeds itself continuously, amplifying the impacts over time. In the beginning, the growth may seem slow, but year after year, it goes faster and faster (see typical growth in savings in Figure 1.12). The more money is there, the more is added. This kind of growth is called exponential in mathematical terms (and there is an equation to describe this curve as a function of time).

Figure 1.12. Growth of account balance with a 6% interest rate.

Credit: Mark Fedkin

Evidently, exponential growth can be a good thing or a bad thing, depending on what stock is growing. Here are some other examples of growth stimulated by positive feedback:

• The more chickens there are in the barn, the more eggs they can lay. The more eggs there are to hatch, the more chicks will be produced which will grow the population of chickens.
• The more soil is eroded, the fewer trees are able to grow on it. The fewer trees there are to stabilize the soil, the more erosion will occur.
• The more individuals are infected with a virus, the more people they can potentially infect. The unrestricted dynamics of virus spread follow the infamous exponential curve.
• In war or conflict, the more damage one side causes to the other, the more hatred and resistance are generated from the other side back to the first. Stronger pushback causes even harsher aggression, thus escalating the conflict.
• The more a child plays a musical instrument, the more pleasure she gets from the sound, and the more willing she is to practice more.

Now think and add a couple of examples to the list. Can you draw a system diagram for any of these examples?

The positive feedback reinforces any change in whatever direction it goes. For that matter, it can be the reason for growth, and it can be the reason for decline and collapse. For example:

• Profits fall because investments fall, but investments fall because profits fall…
• The poorer people are, the harder it is for them to get an education. The less education they have, the harder for them to get out of poverty.

In the context of sustainability, positive feedbacks are classic de-stabilizers, often catering to short-term gains. Although called “positive”, ironically, these feedbacks can be responsible for “runaway” and “snowballing” effects, throwing the system out of balance and often leading to crisis, especially when system growth starts to push against system boundaries.

Negative feedbacks

Consider this example. The population of deer in the area leads to a higher rate of road collisions. The collisions kill a certain number of deer, thus reducing its population. Once the population of deer goes down, the road collisions become less frequent.

Figure 1.13. Negative feedback loop consisting of two stocks and positive and negative couplings.

Credit: Mark Fedkin

We can still clearly see here how the result of the first positive coupling affects the initial stock. Such a feedback loop is called negative or balancing feedback (here is the “—“ sign inside the loop), because it does not allow the deer population to grow out of control. Of course, it is a simplified example, and in reality, there may be other ways of regulating the deer population (e.g. hunting) and minimizing collisions (e.g. fences, driver alerts).

Negative feedbacks are mechanisms of stability. They work both ways, not allowing the stock to go too low or too high. These feedbacks are very common in the natural world, where many systems are homeostatic. Some more examples:

• Warmer weather induces more evaporation from rivers and lakes, thus creating clouds, which cool the air temperature. Once the temperature is cooler, evaporation is reduced, thus resulting in fewer clouds and a sunnier sky.
• Carbon dioxide concentration in the atmosphere stimulates plant growth. More plants consume carbon dioxide from the atmosphere due to photosynthesis. Thus, bringing its concentration down.
• Market price variation: if any product becomes of very high demand, its price grows until the supply meets the demand. If the price rises too high, fewer customers would buy it, so the price would go down again.
• An office worker has to work, but feels sleepy, so he may drink some coffee to get his energy up. But drinking too much coffee can cause some health effects from too much caffeine, and he may decide to limit his coffee consumption. Here, the human decision to drink or not to drink coffee attempts to bring the energy level to the optimal level.

Now think and add a couple of examples to the list. Can you draw a system diagram for any of these examples?

When considering system resilience - the ability to bounce back from disturbances – look for negative feedback loops. Negative feedbacks are also culprits of resistance to change. Sometimes, changing undesirable existing practices is difficult because of feedbacks acting within the system.

How to determine the sign of feedback

Here is the rule of thumb for determining whether a feedback loop is positive or negative: combine signs of all couplings involved in the loops. For example: a loop of 2 positive couplings results in a positive loop:

$$( + 1 ) ( + 1 ) = ( + 1 )$$

A loop of 1 negative and 1 positive coupling results in a negative loop:

$$( + 1 ) ( - 1 ) = ( - 1 )$$

This is the same rule that we use in math when multiplying negative and positive numbers. If you count an odd number of negative couplings in the closed loop, the feedback is negative. If you count an even number of negative couplings in the loop, the feedback is positive.

This rule becomes especially useful when you analyze the feedback loops consisting of multiple couplings. Let us check out a couple of examples.

Examples of how feedbacks work in systems

Example 1: Albedo feedback in climate science.

Here we will consider the connections between four natural elements: solar energy absorbed by the Earth, atmospheric temperature, polar ice, and Earth albedo (reflective ability) (Figure 1.14). Polar ice caps play an important role in controlling the amount of solar energy obtained by the Earth. Due to the high reflective ability of ice, overall Earth’s albedo increases with the expansion of polar ice and decreases when ice melts. Here is the positive coupling between polar ice and albedo. When albedo is high, a large fraction of solar radiation is reflected back to space and is not absorbed by the Earth. Therefore, we can draw a negative coupling arrow from albedo to solar energy absorbed by the Earth’s surface. Next, we will establish the positive coupling between the solar absorption and surface temperature. The more energy is absorbed by the earth’s surface, the more heat will be emitted off the ground into the atmosphere, thus raising the atmospheric air temperature. Finally, higher global air temperature will result in a decline in polar caps by causing ice to melt – hence the negative coupling arrow to close the loop of connections. We have a feedback in the system!

Figure 1.14. System diagram for albedo feedback loop.

Credit: Mark Fedkin

To decide whether this feedback loop is negative or positive, we need to count all couplings involved:

$$( + 1 ) ( - 1 ) ( + 1 ) ( - 1 ) = ( + 1 ) \text{ this is a positive feedback! }$$

What does it mean, and what development can we expect from this system?

As we previously learned, positive feedbacks are destabilizing forces, which often lead to the accelerated shift of system from its current state. Indeed, the currently observed rise in global atmospheric temperature (global warming) is responsible for shrinking the polar ice caps. The fast decline in polar ice is observed in both poles and Greenland. This change gradually decreases the Earth’s albedo, and that makes the planetary surface absorb more solar radiation, thus pushing the atmospheric temperature further up. That secondary warming causes more ice melting etc. The more this process continues, the more warming is intensified, and the faster ice melts.

There is strong scientific evidence that the cause of the currently observed global temperature rise is anthropogenic CO2 emissions. And albedo feedback is an additional amplifier that can act fast and push the warming to much higher rates than CO2 alone.

This positive feedback can work in reverse as well. In the history of the Earth, the albedo feedback played a big role in establishing the “ice ages” on Earth, which were accompanied by very fast expansion of glaciers (polar caps) towards the continents.

Example 2: Fish Pond

This example presents a much smaller system that is a very typical example of ecosystem that has reaching its carrying capacity. Imagine a small pond with a certain population of fish in it. To survive, the fish needs some food and oxygen in the water. The stock of fish is regulated by the factors such as reproduction rate and death rate. Let us identify some key couplings:

• Reproduction rate is positively coupled with the number of fish. The higher the reproduction rate, the high the fish population
• Death rate is negatively coupled with the number of fish. The high the death rate (for any reason, e.g. environmental conditions, disease, predators), the lower the fish population

We can depict these relationships in the system notation as follows:

Figure 1.15. Reproduction rate and death rate of fish.

Credit: Mark Fedkin

• Food availability in the pond favors fish growth and reproduction rate. So this is a positive coupling.
• In a finite-size system like a pond, the food supply can be limited, so if it is too low to support all the fish, fish will starve and die. Hence we can assume the negative coupling with the death rate

Let us add it to the diagram:

Figure 1.16. Reproduction rate, food availability, and death rate of fish.

Credit: Mark Fedkin

• The same as with food, oxygen supply is important for fish population health and growth – this is another positive coupling.
• The limited oxygen supply due to any factors (e.g., eutrophication, overpopulation, etc.) will stress the fish, limits its reproduction, and possibly increase the death rate as well – this another negative coupling.

Figure 1.17. Factors impacting fish longevity

Credit: Mark Fedkin

There are a couple more important arrows to add:

• The more fish are there in the pond, the less food remains available (food is not unlimited). This is the same situation as we have in any ecosystem, including humans – you need more and more food to feed a larger population. So we will draw a negative coupling between Fish and Food availability.
• The more fish are there, the less oxygen is available. While the atmosphere can be considered unlimited compared to the size of the pond, oxygen has a limited and quite low solubility in water. Fish will consume it by breathing, but also dead fish decomposition will consume some of it. So there is definitely a negative coupling between the Fish and Oxygen.

Putting these final two connections onto the diagram, we obtain:

Figure 1.18. Factors impacting fish longevity

Credit: Mark Fedkin

Now let us identify the feedbacks. Are there any closed loops in the diagram? To have a complete feedback, we must be able to trace the couplings in one direction.

Now let us determine whether each feedback is negative or positive using the rule of thumb explained in the previous sections. For example, for the upper left loop, starting with Fish, we have:

$$( - 1 ) ( + 1 ) ( + 1 ) = ( - 1 ) \text{ It is a negative feedback! }$$

We can do the same to identify the other three loops in the diagram:

Figure 1.19. System diagram for Fish Pond system with four negative feedback loops (colored circles). Multiplication rule of thumb is shown for each loop to determine the feedback sign.

Credit: Mark Fedkin

This system appears to be full of negative feedbacks, and that is quite common for natural ecosystems. There are many regulating factors that keep the population of biological species in check. Once the system starts growing out of its capacity limits (food, oxygen supply), the feedbacks start dialing the numbers down until the optimum state (homeostasis) is restored. This example is a demonstration of how negative feedbacks tend to maintain the stability of the system at a certain level. Here we have as many as four mechanisms that help the system execute this goal.

Feedback loops with human decisions

The beauty and power of the system approach is that it can help explore inter-domain connections. Many systems currently exist at the interface of the natural and technological worlds and hence can include factors of economic, social, and environmental nature.

Many causal connections in the environmental systems are sort of predetermined and dependent on the laws of nature. For instance, if temperature increases, gas solubility in water decreases. If a ton of coal is burned, a certain amount of heat is released. If the ocean becomes more acidic, carbonate shells do not form. Those things are just physics and chemistry – there is no intelligent ruling behind them. However, causal connections may be different in human systems, because very often humans have a choice: to turn left or right; to approve or reject a policy; to invest or not to invest; to start the war or negotiation. Those decisions can make an impact within the system, but it does not mean they control the system. In fact, some intelligent (or dumb) decisions can very much be a product of system behavior. In other words, people may take decisions without realizing that they are being controlled by the system itself!

We mentioned before that one of the important system’s properties is function or purpose. The word purpose is more linked to human thinking, so systems can be created to fulfill a particular purpose. The word function is more typical for non-human systems, and function is often visible from the system’s behavior. Please note that human decisions can be made with a purpose in mind, but that purpose in the mind of an individual (perceived or apparent purpose) does not necessarily coincide with the purpose of the system (actual purpose). This is an important distinction. Here are some examples of such dual-purpose dilemma:

• A musician may initially perceive their career in the music industry as art and a way of self-expression (perceived purpose), but the system may steer them towards songs that gain most popularity and make the most money (actual purpose);
• A parent chooses to punish their child for bad grades with the purpose to make them work harder and to improve learning (perceived purpose), but punishment may cause the child to hide their grades or cheat for the sake of a better grade (actual purpose);
• Cat meows loudly in the middle of the night to demand food from the owner. The owner gives the cat the food so that it let her sleep. But guess what – the cat comes back to meow every night now! Perceived purpose = keep the owner happy, actual purpose = keep the cat happy.

Understanding the system behavior can actually help us make smart decisions and steer the system purpose in the desired direction, even those decisions are not always intuitive.

Example 3: Honey Bee Hive

There are a number of environmental factors that sustain the purpose of the honey beehive. It needs a specific habitat with natural flora that provides bees with sources of nectar, clean air and water, which sustain vegetation. Human activities, such as agriculture using pesticides, industrial development, and water and air pollution can be highly disruptive to honey bee populations. We will try to put those factors onto the system diagram (Figure 1.20).

You can identify the positive feedback in this system, which is responsible for ecosystem growth under healthy environmental conditions, with bees and plants mutually benefitting each other. The anthropogenic (human activity) factors, shown by shaded circles, are negatively coupled with different factors in the system. We know that when a positive feedback exists in the system, it can work both ways. A drastic decrease in any of the factors in the loop can result in a fast decline of the entire system.

Figure 1.20. System diagram for the honey beehive system. The anthropogenic factors (shown by shaded circles) negatively impact the bee population directly and by undermining the key stocks: flora and clean air.

Credit: Mark Fedkin

Human decisions can interfere. For example, a decline in the main stock – honey bee population - below a certain critical level can be an alarm signal for the local conservation agencies, who can work with policy makers to protect the natural habitat and resources from excessive exploitation or pollution. That additional factor, when introduced to the system, creates several negative feedback loops that forcefully regulate the industrial factors and keep the system in balance (Figure 1.21).

Credit: Mark Fedkin

Sustainability in system thinking

So, what would make the system like the ones exemplified above sustainable? A simple answer within the arbitrarily identified boundaries would be: the balance of the main stocks. The balance does not mean constancy, but rather refers to a range where system can recover from stock fluctuations through internal mechanisms. We already saw how stocks can be regulated by feedback loops that involve both physical forces (natural laws) and intellectual forces (human decisions). Here, we come to an important observation: human decisions need to conform with the natural processes. Natural and human forces must work with each other, not against each other, to support the capacity of the life-providing stocks. This takes us back to the first Hanover Principle of sustainable design. Systems thinking brings us to the right mindset for applying sustainability principles to a variety of case studies we will discuss in the remainder of this course. To extend your learning of the systems approach, you can refer to the additional reading materials:

Growth

Since this lesson has some analysis and discussions of growth, it would be interesting to see how growth happens in system dynamics. Two types of growth we want to pay attention to are linear and exponential. Linear growth is when a value grows at a constant rate (slope). Positive couplings in systems are a usual cause of linear growth. For example, more product sold means higher profit; more fuel burned, more energy is released – those are simple observations. Exponential growth is different – it goes at an increasing rate – it accelerates! Systems with positive feedback loops often exhibit exponential growth, because the initial stock is continuously compounded by the positive couplings included in the loop.

Mathematically, these two types are schematically represented in Figure 1.22.

Figure 1.22. Graphic and mathematical representation of linear (left) and exponential (right) growth.

Credit: Mark Fedkin

One of the examples shown in the previous section was about the bank account with interest. Adding interest to your balance increases the initial stock and thus earns you higher interest. This illustrates how a positive feedback works. Another example is population growth. When unhindered, the positive feedback loops are expected to cause exponential changes in system stocks.

Example: How to Use Exponential Formula

$$\mathrm{f} ( \mathrm{x} ) = a b^{\mathrm{x} }$$

This mathematical expression generically represents an exponential process. In this formula:

f(x) is a function – the amount we try to track over time. In the case of a bank account, it will be the account balance, or in case of population growth - the number of chickens, bacteria, or people.

a is the initial value, e.g., the account balance to start from or starting population of species.

b is the base, which indicates the factor by which the initial amount changes per unit of time. For example, if the number of bacteria doubles every hour, b=2. Or if the bank account grows by 6% every year, b=1.06.

x is an exponent, which acts essentially as a time coordinate. For example, if you try to calculate the function for 10 hours ahead, x=10.

Starting with 1 bacteria (a=1) and hourly doubling increase (b=2), in 10 hours we will have $f ( x ) = 1 \times 2^{10 }= 1024$ bacteria.

Figure 1.23. Exponential growth with doubling rate.

Credit: Mark Fedkin

From the above examples, we can make a few interesting observations:

• Exponential growth starts slow, but it becomes fast very fast.
• The result of exponential growth is very hard to predict intuitively because we are used to thinking linearly
• Very often, exponential growth is the result of positive feedback in the system
• Negative (balancing) feedbacks are one way to limit system growth
• Exponential growth cannot be sustainable within a finite-size system and reaching capacity crisis is only a matter of time.

Delays

When we discussed couplings in systems, we mentioned that such causal connections exist when A affects B in either a positive or negative way, but we did not pay much attention to how fast that happens. Some changes can be almost instantaneous (or at least seem like that). For example, clouds moving across the sky immediately change the flow of solar energy coming down to earth, and suddenly we feel cooler, or if the sunlight is used for electric generation, the voltage of the solar panel quickly drops. But other changes may take minutes, hours, days, years, and even millennia. That essentially means we have a delay between the cause and its effect.

Examples of systemic delays are multiple. Here are just a few:

• Incubational period of a viral disease – time between virus entering the body and symptoms
• Forest growth – time between seeds germinate in the soil and trees reaching a certain height;
• Greenhouse effect in climate – time between atmospheric carbon dioxide concentration increase and global temperature increase
• Prices in the market – time between supply or demand grow and decision to adjust the price for a product.

The larger the system, the greater the volume of the stock, the longer it takes for it to respond to change. That is why planetary system often experiences changes (climate, ocean chemistry, geochemical cycles) with significant delays - at the scale of thousands and millions of years. That is why technological, economical, and cultural changes often happen much faster at the community level than at the national level.

Delays are important to take into account in system analysis, since they impact system behavior and resilience. Delays in every coupling in the negative feedback loop would add up, thus postponing system response to perturbation. When uncompensated, the perturbation lasts longer, pulling system further off balance.

One of the favorite examples of systemic delay is shower. Have you ever experienced this situation: the water feels too cold and you adjust the hot water knob to make it warmer, but nothing happens, so you adjust it even more, and a little bit more… and then you feel it! It finally gets warmer, but soon enough it feels too hot, and you jump aside and start adjusting the knob in the opposite direction. It takes quite a bit before it is comfortable to stand under water again, but once you think you finally got it, water gets too cold again, and the fine-tuning continues..

We can also depict this process in a system diagram if you wish:

Figure 1.24. Shower system diagram with water regulation feedbacks. Coldness of water draws down the comfort level and prompts the responder to adjust the knob to increase the hotness of water, which is supposed to bring the comfort level to optimal. There are two negative feedback loops that help stabilize the system. However, the delay in the couplings between the knob adjustment and actual hotness of water felt by the person (shown by red marks) results in the adjustments being disproportional with the anticipated temperature change.

Credit: Mark Fedkin

In this process, the temperature of water goes up and down, only bypassing the optimal comfort temperature, resulting in oscillation. Eventually, understanding the delay, you start being more patient, wait for the change and make smaller adjustments. With a few more overshoots, you finally reach the optimal temperature. The system is stabilized!

Why are you able to stabilize the system eventually? In the process of regulating water temperature, you learn – you get information about how long the delay is between the knob turn and actual water temperature change. You also learn how much the temperature changes per certain degree of knob turning. Of course, you process this information almost subconsciously, and it takes a little bit of trial and error.

Figure 1.25. Common oscillation pattern for a parameter observed in systems that are regulated by negative feedbacks with delays.

Credit: Mark Fedkin

Many other systems with negative feedbacks – for instance, regulation of inventory stock based on supply and demand, regulation of earth climate by biota – may exhibit similar oscillations that complicate the system behavior.

Very often, regulating the system operation to improve its performance comes down to managing its delays. Interestingly, acting fast in the system with delays may only exacerbate the situation and make negative impacts and further delays even more dramatic. Instead, understanding delays and letting them run their course may be a better strategy to optimize system performance [Eakes, 2018].

Tipping points

Tipping points is another interesting phenomenon that occurs in some systems. This topic can certainly be a subject for a deeper discussion, but it is worth mentioning it here at least briefly.

Tipping point is a special condition in a system, at which a very small perturbation or causes a large or even catastrophic change. Obviously, the small change is not the main cause, but only a trigger, the last drop in a long and sometimes complicated chain of interactions and events that lead the system to this condition. The term “tipping point” originated in the mathematical catastrophe theory and only recently started to be used in the global environmental context. Most frequently, tipping points are investigated in the relation to climate science and ecology.

Tipping points are frightening because they are not easily predictable, and when the tipping events are triggered, there is no way to reverse the process. Also the events that occur when a system passes through a tipping point are usually dramatic, proceed at a high rate, and have no forewarning. Therefore, understanding the nature and the actual causes behind the tipping points is important for designing preventive measures. Tipping points are very characteristic of systems with counteracting negative and positive feedbacks.

If you are compelled to read more about this concept, additional explanations and some good examples are given in the following reading:

It should be understood that tipping points are not results of external forces, which can also cause dramatic shifts and catastrophes, but are rather internally justified. Another take-away is that, like any other systemic phenomena, tipping points can happen in both natural and social worlds – they are not only confined to the physical processes. Tipping points are observed in societal systems and can be marked by major paradigm shifts, dramatic changes in thinking, decision making, and political transformations. It is very possible that passing of the human society from the current state to a new state with a higher degree of sustainability may also require passing through a tipping point when some traditional worldviews are rejected, and new ones are adopted. Hence, the tipping points do not only present risks, but also opportunities in socio-economic evolution.

Boundaries and system hierarchy

It should be noted that any system model is always a simplification, and system analysis has to be iterative to identify the most significant controls and relationships that determine system operation and stability. Although limited, system analysis can provide interesting insights into system behavior, helps understand the trends in social and technological development, and provides grounds for short-term and long-term predictions.

While real systems are often complicated, making the system model overly complex is not practical - it is important to set boundaries, which would help constrain the analysis and provide answers to practical questions. Boundaries are defined by the observer. Boundaries do not mean that the system is isolated from the outer world, they simply set limits; any entities beyond system boundaries are assumed to be of minor relevance and are not examined in detail until the current model requires. For example, in the honeybee hive system described earlier, we do not consider the factor of climate, even though it is important. In the short term analysis, we simply assume it is constant. Also, we do not include economic factors such as the honey market or artificial beekeeping, etc., leaving them outside the system boundaries and just focusing on the health of the natural ecosystem.

Virtually any system is a hierarchy. That means that any system consists of smaller subsystems, and any system, in turn, may be considered as an element of a bigger system. The tree itself is a system; the soil bed is a system; any biological organism is a system with its own control factors. At the same time, the forest can be considered as a sub-system of eco-region, which is, in turn, may be perceived as a sub-system of the planet, etc. This is another reason for setting boundaries and choosing system scale before engaging in system analysis.

Global sustainability system

To set the framework for applying sustainability principles to engineering activities and technologies, let us for a while widen the angle of our view and first look at the global interconnections. Later on, when zooming in to particular processes and technologies, some of these global elements and loops may remain beyond the boundaries of our viewfinder. However, it will be important to keep these large-scale connections in mind.

Figure 1.26. Sustainability framework for engineering.

Credit: Gagnon et al. Sustainable development in engineering: a review of principles and definition of a conceptual framework, November 2008. Gagnon et al.

The scheme in Figure 1.26 includes both physical and social systems in consideration. Physical systems are shown by several overlapping spheres in the upper part of the diagram: the first one is biosphere (which includes the aquatic and terrestrial ecosystems), the second one is the anthroposphere (which encompasses the agricultural, industrial, and urban systems); both of these are positioned at the triple boundary between the atmosphere, lithosphere, and hydrosphere of the earth. The sun symbol above indicates the unlimited light resource. We can expand the anthroposphere box, indicating the significant role played by engineering projects as human activity. Design and engineering result in creation of products, infrastructures, processes, and services, which all increase the extent and influence of the technical cycle. The Engineering Projects box is linked to Individuals box, meaning that technical progress is incurred by and benefits individuals in the social sphere. The feedback we can assume here is possible disturbance of the natural systems due to expansion of the anthropogenic technical systems. This expansion, in turn, can jeopardize the benefits human beings and societies derive from the environment. Individuals are given a central place in the framework since physical and social systems both contribute towards their well-being. The Social Systems box at the bottom of the diagram provides a more detailed representation of those benefits, which include economic, political, scientific, legal, educational values and communications. Shown social sub-systems, such as Families, Communities, Networks, and Organizations, interact to a various degree with the main social systems and fulfill certain functions. This framework diagram is very broad, and each box could be presented as a separate sub-system with its own internal connections. But this is the big picture, which allows us to contemplate on the diversity of the factors that contribute to the sustainability of human society.

Now, think where technology fits into this diagram. Virtually, it fits anywhere at the connections of the anthropogenic spheres with the physical systems. For example, through technologies, society can utilize natural resources. We also understand that technologies can do both: reconcile the processes and matter flows between the anthroposphere and environmental spheres and create conflicts between them. Thus, engineering projects undermining the resilience or adaptability of ecosystems, social systems, or individuals might bring benefits in the short term but are likely to have long-term negative outcomes. What we call sustainable technologies are designed to render the feedbacks and connections mutually harmless or mutually beneficial in the best-case scenario. To assess technologies from this angle, we need to learn to recognize the feedbacks and effects they create on a large scale.

Lesson #1 started introducing you to the sustainability context, reviewing the main philosophical principles of sustainability as well as practical guidelines applied to sustainable design and engineering. From these philosophies, we can clearly see that any analysis of engineering projects, technologies, and processes from the standpoint of sustainable development must be done in a wider framework, which includes environmental, economic, and social forces.

Here, we also browsed through the important background of systems approach, which emphasizes interconnections and feedbacks as controls of system stability or instability. Based on this review, we started to determine the role of technology in the dynamics and function of anthropogenic systems. We can see that technologies work at interfaces between the physical world and society. Technologies can be efficient tools regulating the system inputs and outputs, and also can serve as drivers of change and lifestyle builders in society. This prepares us for the next step – developing the metric system and methods for technology evaluation in the next lessons.

Assignments for Lesson 1

References for Lesson 1: