- Heat transfer can alter system states;
- Bodies don’t “contain” heat; heat is identified as it comes across system boundaries;
- The amount of heat needed to go from one state to another is path dependent;
- Adiabatic processes are ones in which no heat is transferred.
H = Ht + Hv + Hi (1)
H = overall heat loss
Ht = heat loss due to transmission through walls, windows, doors, floors and more
Hv = heat loss caused by ventilation
Hi = heat loss caused by infiltration
Systems thinking involves the use of various techniques to study systems of many kinds. In nature, examples of the objects of systems thinking include ecosystems – in which various elements (such as air, water, movement, plants, and animals) interact. In organizations, systems consist of people, structures, and processes that operate together to make an organization “healthy” or “unhealthy”. Systems Engineering is the discipline that utilizes systems thinking to design, build, operate and maintain complex engineered systems.
SCHOOLS OF THOUGHT
The Circular Economy concept has deep-rooted origins and cannot be traced back to one single date or author. The generic concept has been refined and developed by the following schools of thought:
• Regenerative design (representative: John T. Lyle).
• Performance economy (representative: Walter Stahel).
• Cradle to Cradle (representatives: Michael Braungart and William McDonough)
• Blue Economy (representative: Gunter Pauli)
• Permaculture (representatives: Bill Millison and David Holmgren)
• Biomimicry (representative: Janine Benyus)
• Industrial Ecology (this is more than a school of thought, it is an academic discipline that has been taught from the 1990s)
The evaluation of processes that protect the environment alongside resource and energy consumption to most favourable to least favourable actions. The hierarchy establishes preferred program priorities based on sustainability. To be sustainable, waste management cannot be solved only with technical end-of-pipe solutions and an integrated approach is necessary.
The waste management hierarchy indicates an order of preference for action to reduce and manage waste, and is usually presented diagrammatically in the form of a pyramid. The hierarchy captures the progression of a material or product through successive stages of waste management, and represents the latter part of the life-cycle for each product.
The aim of the waste hierarchy is to extract the maximum practical benefits from products and to generate the minimum amount of waste. The proper application of the waste hierarchy can have several benefits. It can help prevent emissions of greenhouse gases, reduces pollutants, save energy, conserves resources, create jobs and stimulate the development of green technologies.
All products and services have environmental impacts, from the extraction of raw materials for production to manufacture, distribution, use and disposal. Following the waste hierarchy will generally lead to the most resource-efficient and environmentally sound choice but in some cases refining decisions within the hierarchy or departing from it can lead to better environmental outcomes.
Life cycle thinking and assessment can be used to support decision-making in the area of waste management and to identify the best environmental options. It can help policy makers understand the benefits and trade-offs they have to face when making decisions on waste management strategies. Life-cycle assessment provides an approach to ensure that the best outcome for the environment can be identified and put in place. It involves looking at all stages of a product’s life to ﬁnd where improvements can be made to reduce environmental impacts and improve the use or reuse of resources. A key goal is to avoid actions that shift negative impacts from one stage to another. Life cycle thinking can be applied to the five stages of the waste management hierarchy.
For example, life-cycle analysis has shown that it is often better for the environment to replace an old washing machine, despite the waste generated, than to continue to use an older machine which is less energy-efﬁcient. This is because a washing machine’s greatest environmental impact is during its use phase. Buying an energy-efﬁcient machine and using low- temperature detergent reduce environmental impacts.
The European Union Waste Framework Directive has introduced the concept of life-cycle thinking into waste policies. This duality approach gives a broader view of all environmental aspects and ensures any action has an overall beneﬁt compared to other options. The actions to deal with waste along the hierarchy should be compatible with other environmental initiatives.
In economics, the Jevons paradox (/ˈdʒɛvənz/; sometimes Jevons effect) occurs when technological progress increases the efficiency with which a resource is used (reducing the amount necessary for any one use), but the rate of consumption of that resource rises because of increasing demand. The Jevons paradox is perhaps the most widely known paradox in ecological economics. However, governments and environmentalists generally assume that efficiency gains will lower resource consumption and are an effective policy for sustainability, ignoring the possibility of the paradox arising.
In 1865, the English economist William Stanley Jevons observed that technological improvements that increased the efficiency of coal-use led to the increased consumption of coal in a wide range of industries. He argued that, contrary to common intuition, technological progress could not be relied upon to reduce fuel consumption.
The issue has been re-examined by modern economists studying consumption rebound effects from improved energy efficiency. In addition to reducing the amount needed for a given use, improved efficiency lowers the relative cost of using a resource, which tends to increase the quantity of the resource demanded, potentially counteracting any savings from increased efficiency. Additionally, increased efficiency accelerates economic growth, further increasing the demand for resources. The Jevons paradox occurs when the effect from increased demand predominates, causing resource use to increase.
Considerable debate exists about the size of the rebound in energy efficiency and the relevance of Jevons paradox to energy conservation. Some dismiss the paradox, while others worry that it may be self-defeating to pursue sustainability by increasing energy efficiency. However, conservation policies such as green taxes, cap and trade, and emissions standards do not display the paradox, and can be used to control the rebound effect. Environmental economists have proposed that efficiency gains be coupled with conservation policies that keep the cost of use the same (or higher) to avoid the Jevons paradox.[