IB Environmental systems and societies 8.2E Sustainable Urban Systems Notes

Urban Sustainability Models: Circular Economy and Doughnut Economics

Cities use circular economy and doughnut economics as models to plan for sustainability.

Circular Economy: Keeping Materials in Use, Not in Landfill

1. The old linear economy runs on a take, make, dispose path that turns raw materials into waste.
2. A circular economy instead designs out waste, keeps products and materials in use, and regenerates natural systems.
3. When a product reaches the end of its life, it is reused, repaired, or recycled into something new.

Advantages of a Circular Economy

1. Waste reduction: keeping materials in use cuts the amount of waste sent to landfill.
2. Resource efficiency: favours renewable inputs and lowers the pull on finite raw materials.
3. Economic gains: repair and reuse create green jobs and reduce reliance on outside supply chains.
4. Lower carbon footprint: less new production means less energy use and fewer emissions.

Doughnut Economics: A Safe and Just Space Between Two Rings

Doughnut economics, set out by Kate Raworth, balances human needs against the planet's ecological limits.

1. The inner ring is the social foundation, a floor of basic needs such as food, water, health, housing, and education that no one should fall below.
2. The outer ring is the ecological ceiling, the planetary boundaries that societies must not overshoot.
3. The safe and just space is the doughnut itself, the ring between the social floor and the ecological ceiling.

Advantages of Doughnut Economics

1. Social equity: all residents can reach the resources they need for a dignified life.
2. Environmental limits: respecting ecological boundaries prevents overuse of natural resources.
3. Holistic view: it weighs social, economic, and environmental factors together.

Green Architecture: Buildings That Cut Harm to People and Planet

1. Green architecture uses sustainable materials and energy-efficient methods to cut harm to health and the environment.
2. It leans on renewable and recycled materials, low energy use, water saving, and reuse of building materials.

Four Green Building Methods and Their Advantages

Bale Construction

1. Bale construction uses straw bales as the main building material.
2. Straw is a farm byproduct, so it is cheap, renewable, and natural.
3. Straw bales give strong insulation, holding a steady indoor temperature in hot and cold climates.
4. Energy efficiency: high insulation lowers heating and cooling costs.
5. Carbon storage: straw takes in carbon dioxide as it grows, offsetting some building emissions.
6. Low impact: straw bales are biodegradable and cause little environmental damage.

Bottle and Plastic Construction

1. Bottle and plastic construction reuses recycled bottles and waste plastic as building material.
2. Discarded bottles and containers are packed into walls, insulation, and other parts of a building.
3. Waste reduction: plastic that would reach landfill or oceans is locked into the building.
4. Low cost: recycled material is cheaper than new stock, which suits low-cost housing.
5. Insulation: bottle walls help insulate, cutting the need for artificial heating and cooling.

3D-Printed Houses

1. 3D printing builds whole houses or parts of them layer by layer.
2. It can print with concrete, bioplastics, or even recycled waste materials.
3. Material efficiency: it lays down only the material needed, so less is wasted.
4. Custom design: shapes can be tailored, including energy-efficient designs.
5. Affordable housing: fast printing lowers labour costs and helps address housing shortages.

Arabic Wind-Tower Houses (Barajeel)

1. The wind tower, or barajeel, is a traditional design from the Middle East, seen in the UAE, Oman, and Iran.
2. The tower catches cool breezes and channels them indoors for natural ventilation in hot climates.
3. Natural cooling: airflow cools the building, reducing the need for air conditioning.
4. Cultural fit: it joins traditional knowledge with modern needs and local identity.
5. Resource efficiency: the tower uses no electricity, so it lowers total energy use.