SOHO Systems
Contents
"On Complexity Theory, Exergy and Industrial Ecology: Some Implications for Construction Ecology" James Kay, 2002
This article was written by James Kay for Construction Ecology: Nature as a Basis for Green Buildings, Kibert, C., Sendzimir, J. (eds), Guy, B., Spon Press, 2002, pp.72-107.
Premise
Kay quotes Graedel and Allenby that industrial ecology is ".e.. the means by which humanity can deliberately and rationally approach and maintain a desirable carrying capacity, given continued economic, cultural and technological evolution. The concept requires that an industrial system be viewed not in isolation from its surrounding systems, but in concert with them."
Kay argues that sustainability must be considered at a system level. He goes on to say that "... all man-made systems must contribute to the survival potential of natural ecosystems (through) a new branch of engineering (that) will bring together the disciplines of ecology, economics, engineering design, systems theory, and thermodynamics."
Characteristics of SOHO Systems
Kay states that open systems that process high quality energy (exergy) display "spontaneous coherent behavior and organization." Exergy and material inputs push the system away from equilibrium. At a critical point, organized behavior emerges "that uses the exergy to build, organize and maintain its new structure." Additional exergy leads to increased structure, improving the ability to use more resources in a feedback loop. At some point, the system is overwhelmed and becomes chaotic.
Exergy gives rise to processes that restructure resources to dissipate that exergy, constrained by the context of the system. This in turn gives rise to new structure, which creates a new context at multiple levels, allowing nested (hierarchical) processes and structures to emerge. These systems are hierarchically nested, working at multiple levels.
Although the system structure and process are constrained by the exergy/material/information inputs and the system context, the specific structures and processes are uncertain. A system may have many 'steady states', some of which may be more desirable, but all equally 'correct'. SOHO systems are sensitive to initial conditions (chaotic behavior) and may respond non-linearly to changes in the context or flows (bifurcation, flips, Hollings four-box cycle <need to read up on this>). Kay uses the example of how increased phosphorous can cause a lake system to shift from a benthic to a pelagic state, which is stable until phosphorous levels are reduced below a critical point (p12).
In general, ecosystems develop to increase the degree to which they degrade (reduce the quality) of solar exergy. Studies show that mature ecosystems re-radiate energy at the lowest temperature, because they have more pathways that use (dissipate) solar energy. Disruption to plant communities result in warmer surface temperatures until the system can adjust. Similarly, plants taken out of their environment show the same increase.
Kay lists the following properties of SOHO systems:
- open
- exist in quasi-stable states that are not at equilibrium
- maintained by energy gradients (exergy) across boundaries
- gradients are irreversibly degraded to build and maintain processes and structure
- feedback loops, cycling, autocatalytic
- holarchically nested (need to study as a whole, at different scales)
- multiple steady states
- non-linear, sensitive to initial conditions (may exhibit unpredictable or chaotic behavior)
- self-organizing (non-Newtonian, cannot be studied as a 'mechanism')
- window of vitality (just enough complexity - neither minimum nor maximum)
As dissipative systems become more organized, they:
- capture and use more exergy (more energy flow activities)
- build more structure
- more cycling of energy and materials (more cycles, longer length, less leaky, longer turnover)
- higher average trophic structure (longer trophic food changes, species occupy higher average trophic levels, greater trophic efficiency) <not sure what all this means>
- higher respiration and transpiration
- larger ecosystem biomass
- higher diversity
- change in spurts as new attractors become accessible
- resist moving further away from equilibrium (more exergy required)
Although Kay talks about SOHO systems enhance their survivability by using resource more effectively and building more structure, he also suggests that survival may not be consistent with maximum exergy degradation (without expanding on this point). Again, no single 'best solution' can be determined.
Challenges
Kay argues that there is currently limited motivation to using the design principles suggested by an understanding of SOHO systems - this needs to be addressed through concepts such as ecological economics. More critically, the tools to analyse mass-energy-information flows are lacking, particularly with respect to quality of flow and effectiveness (second law of thermodynamics). Lastly, we have limited knowledge of how complex, adaptive, self-organizing, hierarchical ecological systems work, although Hierarchy Theory (Allen, Hoekstra, Starr) shows promise in dealing with the overall structure.
Relevance to Design
According to Allenby, sustainability can only be discussed at the biosphere level - it is not relevant to talk of a sustainable process or plant. Kay defines industrial ecology as "... the activity of designing and managing human production-consumption systems, so that they interact with natural systems, to form an integrated (eco)system which as ecological in integrity and provides humans with a sustainable livelihood." Ecological integrity includes:
- current well being (vigor, health, vitality)
- resiliency (ability to deal with external stresses, which may involve a flip to another attractor)
- capacity to develop/adapt/evolve (continual self-organizing, regenerate through birth-growth-death-renewal, allow complexity to emerge by spontaneously switching attractors)
Societal systems depend on the flow of exergy, materials and information from ecological systems. The ecological systems define the context for the societal systems, constraining their structures and processes. Societal systems can influence ecological systems by:
- changing the structure of the ecological system, which alters the flows to the societal system
- changing the context of the ecological system, which influences the ecological processes and in turn the ecological structures
Both changes can influence the context of the societal systems, affected their processes and structures.
Understanding SOHO systems requires:
- hierarchical systems description of processes/structures, their contexts and their relationships
- identification of self-organizing behaviours
- attractors
- feedback systems
- external influences defining the context
- conditions under which system flips between attractors
Narratives or scenarios may be better able to capture the possibilities than existing analytical methods based on reductionist methods.
Energy flows can be described using Network Thermodynamics and graph theoretic techniques. It is important to consider both quantity (joules or equivalent) and quality (measured in exergy) and document the change in both metrics between the inputs and outputs of components. Methods for measuring the quality of materials and information flows are currently lacking. <does this link the Julian's comments on Survival Strategies about working with the inherent structure of materials?>
Efficiency vs. Effectiveness
Efficiency is how well the quantity of flow is used, while effectiveness is how well the quality is used (for energy, as measured by exergy density). Electrical heat is 100% efficient, but gas heat is more effective (electricity could be better leveraged powering a heat pump). Natural systems actually do not appear to be particularly efficient - only 2% of solar energy is converted to biomass, yet ecosystems are 80% efficient. <Kay does not explain how these values are obtained> <do issues of effectivness part of the explanation for the dramatically lower energy component in natural solutions (Julian's Survival Strategies)?>
The distinction between effectiveness and efficiency may also underlie Kay's statement that non-linear systems cannot be optimized at a component level. Optimizing a part of the system causes other parts to move away from their optimum states to accommodate the change.
Design Strategies
Kay recommends dealing with the uncertainty inherent in SOHO systems through:
- adaptive management: build in the ability to change and adapt
- inherently flexible
- comprehensive monitoring
- the precautionary principle
- limit effluents
- minimize displacement of the landscape
- decrease our use of energy
Strategies for dealing with change include:
- take control of the environment (beaver dams)
- isolate the system from the environment (filtration, affecting weather patterns)
- adapt to the environment by changing the behavior or role of elements, changing elements themselves, or changing the interconnection between elements
Nature tends to emphasize the last strategy <what about ecosystem engineers?>, while we emphasize the first two. Kay points out that we have different priorities: we value human life and try to minimize hardship. These factors would lead to a different balance between approaches and strategies.
Kay lists four design principles:
- Interfacing: maintaining the survival potential of natural ecosystems
- Bionics: large scale structure and behavior of man-made systems should be similar to those of natural ecosystems (Papanek)
- Mimicry (appropriate biotechnology): where possible, a subsystem of the natural biosphere should deliver functions of man-made systems
- Renewable Resources: non-renewable resources need to be treated as capital expenditures in the process of switching to renewable resources
Interfacing
Interfacing requires a full account of all relevant flows and effects of changes in flows on self-organization, at multiple spatial and temporal scales. The two forms of feedback between societal and natural ecosystems needs to be analyzed. It is important to recognize the non-linear behavior of SOHO systems: once the buffering systems are overwhelmed, even small changes can result in large effects on the system state.
Bionics
Kay mentions the 1997 CHMC FLEX housing project as an example of a building that can adapt over time. Tradeoffs between capital costs/efficiency need to be weighed against the overheads of flexibility, redundancy, renewability and monitoring.
Mimicry
Examples of appropriate biotechnology include natural storm water management systems, that cost 10% less than traditional solutions in both capital and operating costs. Other examples include water cycling, greening cities, Living Machines, and community sewage treatment.
Kay cautions that some mimicry is based on a flawed view of ecosystems as super-efficient, closed loop and highly tuned. Ecosystems reflect a historical balance between coping with change and making good use of resources. Again, the unique priorities of humans may result in a different balance.
Renewable Resources
Resources are in themselves not renewable. The critical factor is how they are used, at a rate such that the stock of resource does not decrease. Examples include design for efficiency, minimizing the ecological footprint, and building standards (e.g. LEED).
Examples and Applications
Kay describe an approach to 'construction ecology' that results in buildings which are resilient, can adapt/evolve, and fit into the natural environment. Factors include:
- taking into account different types of perspectives at different scales
- context of energy and material (<and information?>) flows
- ability to incorporate different flows over time (e.g. shifting recycling streams)
- how building fits into the larger societal/natural systems
- University of Waterloo was able to implement water recycling because they only had two connections to the city water system
Design Implications
Kay believes it is important to incorporate ethics and values into discussion of design:
- identify the players and their issues
- build a systems description of the situation
- develop an ongoing adaptive management strategy
- implement a governance structure
According to Kay, "We can no longer treat our designs as mechanical clock work edifices designed to withstand the test of time." Design is no longer seen as finding a 'right' solution to a problem, but rather a process for evolving the built environment to meeting changing needs and conditions. Instead of static structures, we need to develop dynamic processes.
