Green design

Summary: Green design requires evaluating the life cycle of a product or material and the cost of that life cycle in energy and other resources.

Green design, also called “environmental” or “sustainable design,” is a set of design principles for optimizing environmental impact. This includes reducing pollution, promoting ecological and economical sustainability, using reusable resources, and promoting harmony between people and natural environments. Mathematics plays a significant role in both designing green solutions to a variety of problems and measuring the impact of green solutions. Many colleges offer degree or internship programs in green design, which requires strong science and mathematical skills.

Impact Measures

Ecological design employs a series of metrics for evaluating the degrees of sustainability. A mnemonic used for types of sustainability is “Three Rs”: reduce, reuse, and recycle. Reducing waste, pollution, and resource use involves calculations of the impact of production, packaging, transportation, and disposal, as well as renewability of resources. Some design movements, such as Tiny Houses, are predominantly based on the principle of reducing space and resources. Reuse design principles allow objects to be used multiple times, possibly for different purposes. Recycling is the ability to turn objects into materials for making other objects.

The notion of life cycle is central to measuring environmental impact. For example, product life cycles include research and development, main use, and disposal after use. Different stages in the cycle require different types of impact measures. Green design has to address all the stages, from sustainable research practices to possibilities of reuse and recycling at the last stage of the product’s life.

There are numerous rubrics and point systems for measuring environmental impacts of industrial, product, or architectural designs. For example, products, activities, or organizations can be measured by their resource intensity, with amount of resources used per unit cost. A toy designer can calculate liters of water spent during manufacture per dollar of the toy’s cost. The inverse of resource intensity is resource productivity, measured in quantity or price per unit of resource spent. In this example, resource productivity is the price, in dollars, of toys produced using one liter of water.

Leadership in Energy and Environmental Design (LEED) is an international green building certificate. To give a building or a community its score, LEED combines metrics, such as the carbon footprint, as well as energy and water efficiency. LEED has separate ratings for construction of commercial buildings and homes, interior design, maintenance of existing buildings, and neighborhood development. In each category, the maximum score is 100 points, with certification levels of Platinum (more than 80 points), Gold (60–79 points), Silver (50–59 points), and Certified (40–49 points).

There is a global mathematical problem involved in measuring and reducing environmental impact of design. Namely, there are money and environmental price differences between different design types, and noticeable costs of certification and measurement. The overall sustainability measures have to include all these costs and optimize the total. Because many current economical practices are standardized in nonsustainable manners, the economy of scale makes their use cheaper than the corresponding green designs. This phenomenon is being addressed at the government level by changing price and tax structures to promote sustainable practices.

Green Urban Design

New urbanism is an example of urban design that includes several green principles, including jobs within walkable distances, bike-friendly roads, shared public and housing spaces, diverse communities, and matching local terrain and conditions in landscaping. Geometries of new urbanist designs are concentric and include discernible centers for neighborhoods, such as a historical artifact or a town square, with a transit node tied to this center for optimized logistics. Houses of different types, matching a variety of family and economic situations, are situated within the five-minute walk radius (about one-half kilometer) from this center, and commercial properties surround the houses. The design of roads uses network science to slow down car traffic, minimize travel, and place important administrative, educational, and religious public buildings in traffic network nodes. This relatively compact design, the opposite of urban sprawl, also helps make electricity, water, and gas distribution more efficient, because less energy is spent on delivering these resources and less is lost in transit.

Models from Nature

One of the principles of green design is the use of models found in nature to build products or systems. For example, thermoeconomics models the design of social structures on the laws of thermodynamics. Economical entities are considered on the basis of energy, matter, and information involved in them. Production and use of goods and services are seen as energy and mass exchange, and scarcity has to do with entropy.

The concept of exergy is especially important in industrial design. Exergy is the maximum work theoretically possible as a system reaches energy equilibrium with its surroundings. The second law of thermodynamics says that systems tend to dissipate energy or increase entropy. This loss of exergy is called “anergy.” Green designers use both energy and exergy efficiency. Energy efficiency measures how much energy is lost during industrial processes. Exergy efficiency has to do with minimizing anergy, that is, the loss of exergy.

Some social designers consider the total exergy of Earth or even the solar system, working toward designs at these large scales. For example, burning oil or coal produces heat, but these fuels also required inputs of exergy in their making. A mathematical model can approximate the history of the fuels and incorporate their current use, computing energy and exergy efficiency of our actions with regard to Earth, and the sustainability of Earth, over time.

Biomimicry, biomimetics, and bionics are direct uses of design ideas and principles found in nature. For example, engineers studied birds and insects to develop flying devices. More recent examples have to do with efficiency and sustainability. The shape of nautilus shells, mathematically related to the Fibonacci sequence named for mathematician Leonardo Fibonacci, is used to minimize friction in fans, conserving energy. The mechanism of water condensation used by desert beetles can be applied on the human scale. The ways termites keep their mounds warm at night and cool during the day are studied to produce sustainable air conditioning in houses.

Designers and engineers rarely repeat natural designs completely but rather analyze them to find appropriate elements and include elements into the design. There are three directions for such analysis. Designers can incorporate methods of manufacture found in nature, such as the strong material of the mussel’s shell. They can mimic mechanical or thermodynamical principles found in nature, for example, the way butterfly wings are colored as the basis of energy-efficient displays. Finally, designers can look at the global organizational principles found in nature, such as modeling a robotic cleaner on insect scavenging behaviors or building artificial intelligence based on the ways brains work.

Bibliography

Andraos, John. The Algebra of Organic Synthesis: Green Metrics, Design Strategy, Route Selection, and Optimization. Boca Raton, FL: CRC Press, 2011.

Passino, Kevin. Biomimicry for Optimization, Control, and Automation. New York: Springer, 2004.

Vallero, Daniel, and Chris Brasier. Sustainable Design: The Science of Sustainability and Green Engineering. Hoboken, NJ: Wiley, 2008.