Extensive green roof

Definition

An extensive green roof is a type of green roofing system characterized by a thin layer of lightweight soil and vegetation, designed to be low-maintenance and support a limited variety of drought-resistant plants. This system primarily aims to enhance the building's energy efficiency, improve stormwater management, and provide ecological benefits without requiring significant structural support. Its implementation contributes to urban biodiversity and helps mitigate the urban heat island effect.

5 Must Know Facts For Your Next Test

1. Extensive green roofs are typically composed of a drainage layer, a lightweight growing medium, and vegetation that requires minimal maintenance, such as sedums and other succulents.
2. These roofs usually have a growing medium depth of 2 to 6 inches, making them much lighter than intensive green roofs, which require more structural support.
3. Extensive green roofs can significantly reduce rainwater runoff by absorbing and retaining stormwater, thus decreasing the risk of urban flooding.
4. They provide insulation for buildings, reducing energy consumption for heating and cooling, which contributes to lower greenhouse gas emissions.
5. Implementing extensive green roofs in urban areas promotes ecological benefits by creating green spaces that support pollinators and improve air quality.

Review Questions

• How do extensive green roofs differ from intensive green roofs in terms of maintenance and plant selection?
  • Extensive green roofs are designed to be low-maintenance and typically feature drought-resistant plants like sedums, while intensive green roofs support a wider variety of plants but require more care and irrigation. The shallow growing medium in extensive systems limits plant diversity, focusing on hardier species that can thrive in minimal soil depth. In contrast, intensive systems have deeper soil layers that allow for more lush vegetation but demand greater maintenance efforts.
• What role do extensive green roofs play in mitigating the urban heat island effect?
  • Extensive green roofs help mitigate the urban heat island effect by providing a vegetative layer that absorbs sunlight and reduces the overall temperature of the building's surface. By replacing traditional roofing materials with living vegetation, these roofs reflect sunlight and cool the air through evapotranspiration. As a result, extensive green roofs contribute to lower ambient temperatures in urban areas, enhancing comfort for residents and reducing energy demands for cooling.
• Evaluate the environmental benefits of extensive green roofs in urban settings, especially regarding stormwater management and biodiversity.
  • Extensive green roofs offer significant environmental benefits in urban settings by improving stormwater management and promoting biodiversity. They effectively absorb rainwater, reducing runoff and minimizing flood risks during heavy rainfall events. Additionally, these roofs create habitats for various species, including birds and insects, enhancing urban biodiversity. By integrating extensive green roofs into city planning, urban environments become more resilient to climate change while supporting ecological health.

Related terms

Vegetated Roof: A roofing system that incorporates plants and soil, which can be extensive or intensive based on plant diversity and depth of growing medium.

Urban Heat Island Effect: A phenomenon where urban areas experience higher temperatures than their rural surroundings due to human activities and altered land surfaces.

Biodiversity: The variety of life in a particular habitat or ecosystem, which extensive green roofs can enhance by providing habitats for various species.