Ecological urban planning is guided by urban compactness, mixed land use, and social mix. Together, these principles treat a city as an interconnected ecosystem, reducing resource consumption while improving accessibility and social sustainability.
This content belongs to IB ESS subtopic 8.2 Urban systems and urban planning. Ecological urban planning is core at SL and HL, while the three named principles are HL only.
| Principle | Mechanism and benefits | Limitations or trade-offs |
|---|---|---|
| Urban compactness | Concentrates homes, services and employment in a smaller area. Shorter journeys support walking, cycling and public transport, reducing fossil-fuel use, air pollution and sprawl. | High density can increase congestion, noise and pressure on green space. Rising prices may displace lower-income residents. |
| Mixed land use | Places residential, commercial, recreational and institutional functions close together, reducing travel demand and improving access to services. | Incompatible activities may create noise, pollution or health risks, so zoning remains necessary. |
| Social mix | Encourages different income and social groups to share areas, housing and services, improving equity and reducing segregation. | Development may cause gentrification unless affordable housing and community participation are protected. |
From a systems approach, compact, mixed-use cities reduce inputs such as fuel and land, and outputs such as greenhouse gases and air pollutants. Multiple transport options and nearby services may also increase resilience.
Freiburg, Germany, provides a named example. Its Vauban district combines compact housing, nearby facilities, public transport, cycling infrastructure and restricted car use. However, ecological performance does not guarantee environmental justice: planners must consider affordability, accessibility and who benefits from redevelopment.
Exam technique: For an “explain” question, link each principle to a clear environmental or social outcome rather than merely defining it. For “evaluate,” include benefits, limitations, a named example and a supported judgement. Avoid the misconception that greater density is automatically sustainable.
