ESS 8.2.3 [AHL] Sustainable Development & Green Engineering

Learning Objectives

1. To what extent does ecological urban planning follow the principles of compactness, land use and social mixing?
2. Explain how circular or doughnut economics promote sustainability in urban systems.
3. Evaluate the role of green architecture in reducing the harmful effects of construction projects.

Sustainable Urban Development

By Circular Models

Traditional linear economic models follow a “take, make, and dispose” approach. These models depend heavily on extracting natural resources and generating large amounts of waste. As a result, they contribute to environmental degradation, resource depletion, and unsustainable patterns of urban growth.

To address these challenges, many societies are moving towards circular economy and doughnut economy models. These approaches are based on the understanding that the economy, society, and environment are interconnected and depend on one another. Unlike linear models, circular models recognise the environmental consequences of urban development and seek to reduce negative impacts.

In urban areas, circular models focus on keeping resources in use for as long as possible rather than disposing of them after a single use. Waste is viewed as a failure of the system because materials should either be:

• Organic and capable of being regenerated naturally.
• Inorganic and capable of being recovered, repaired, reused, or recycled.

The goal is to minimise waste and maximise resource efficiency. Many circular economy strategies are based on the principles of the 3Rs:

• Reduce resource consumption.
• Reuse products and materials.
• Recycle waste into new products.

By adopting these principles, cities can lower their environmental impact while promoting sustainable economic growth.

By Doughnut Economics

Doughnut economics is a model that aims to balance human well-being with environmental protection. Although it originated in economics, it can also be applied to urban planning and sustainable development.

The model is represented by a doughnut-shaped diagram. The inner ring represents the social foundation, which includes the basic needs required for a good quality of life, such as food, water, housing, healthcare, education, and employment. People who fall within the central hole lack access to some or all of these essential needs and therefore experience deprivation.

The outer ring represents the ecological ceiling, which refers to the Earth’s environmental limits, also known as planetary boundaries. Exceeding these limits can result in environmental damage, including climate change, biodiversity loss, and resource depletion.

The aim of doughnut economics is to ensure that everyone has access to their basic needs while remaining within the Earth’s environmental limits. This creates a safe and just space where human development can occur sustainably.

The Generous City Concept

The concept of the “generous city” was developed by Janine Benyus. A generous city is designed to work in harmony with the natural ecosystem in which it is located. Rather than damaging the environment, the city contributes positively to ecological processes and supports both people and nature.

The development of a generous city involves several key steps:

1. Understanding the local ecosystem and environmental conditions.
2. Studying natural processes such as energy flows, water cycles, soil fertility, and carbon storage.
3. Using this information to guide urban planning decisions.
4. Designing infrastructure that integrates with natural systems, including wildlife corridors, green spaces, and urban farming areas.
5. Creating a distributive and equitable urban system that benefits all residents.

Characteristics of a generous city include:

• Affordable housing for all residents.
• Access to renewable energy at the household level.
• Efficient and affordable public transport systems.
• Neighbourhoods where homes, workplaces, and educational facilities are located close together.
• Strong community participation and environmental stewardship.
• Infrastructure that supports both human activities and ecological processes.

Supporters of this model argue that cities must become regenerative and distributive if they are to remain within planetary boundaries and avoid environmental collapse.

Green Architecture

Green architecture is an approach to building design that aims to minimise negative impacts on human health and the environment. It combines modern technology with traditional knowledge to create buildings that are environmentally responsible and resource-efficient.

In construction projects:

• Architects are responsible for designing buildings and planning their overall structure.
• Civil engineers manage the technical aspects of construction and oversee the project from design to completion.

When architects and engineers work together, they can develop buildings that are more sustainable and efficient.

The main objectives of green architecture are to:

• Reduce the environmental impacts of construction.
• Protect air, water, and soil quality.
• Improve energy efficiency.
• Use environmentally friendly materials.
• Promote long-term sustainability.

Circular Principles in Green Construction

Green architecture often follows circular economy principles. Construction materials are selected based on their ability to be renewed, reused, recycled, or biodegraded.

Examples include renewable materials such as:

• Timber
• Hemp
• Recycled materials
• Biobased products

Modern construction methods, such as prefabrication, are also becoming more common. Prefabricated building components are manufactured off-site and assembled on-site, reducing waste, lowering costs, and improving construction efficiency.

Some modern building materials are even carbon-negative, meaning they remove more carbon dioxide from the atmosphere during their lifespan than they produce.

Biobased Materials

Biobased materials are products derived from renewable biological resources. These materials are increasingly used in sustainable construction because they are environmentally friendly and often biodegradable.

Characteristics of biobased materials include:

• Production from renewable natural resources.
• Extensive processing to improve performance and durability.
• Low environmental impact.
• High potential for biodegradability.

Examples include:

• Cellulose fibres.
• Casein-based products derived from milk proteins.
• Bioplastics made from soy, maize, sugar cane, wheat, or potatoes.
• Corn-starch packaging materials.
• Plant-based lubricants derived from vegetable oils.

These materials help reduce dependence on fossil fuel-based products and support circular economy principles.

Straw Bale Construction

Straw bale construction is a sustainable building method that uses compressed straw bales as structural components or insulation. Although often considered a modern eco-friendly technology, straw has been used in construction for thousands of years.

Today, straw bales are commonly used because they provide excellent insulation and are made from agricultural waste products.

Advantages of Straw Bale Construction

• Uses agricultural waste that would otherwise be discarded.
• Provides additional income for farmers.
• Offers excellent thermal insulation, reducing energy use for heating and cooling.
• Is simple to construct and requires relatively basic skills.
• Uses renewable resources grown through solar energy.
• Is fully biodegradable at the end of a building’s life.
• Has good fire resistance due to the density of compressed straw.
• Can be shaped and adapted to different architectural designs.

Disadvantages of Straw Bale Construction

• Straw must remain dry to prevent decay and mould growth.
• Transportation costs can be high if straw sources are located far from construction sites.
• Building regulations and technical expertise may be limited because the method is still relatively uncommon in many regions.

Conclusion

Circular economy principles, doughnut economics, generous city design, and green architecture all contribute to more sustainable urban development. By reducing waste, improving resource efficiency, promoting social equity, and integrating natural systems into urban planning, cities can become more resilient, environmentally responsible, and better places to live for future generations.