Why might LEED encourage the use of bio-swales or green roofs?

LEED encourages the use of bio-swales or green roofs primarily for their ability to manage stormwater effectively. These features play a critical role in reducing runoff, which helps to mitigate the risk of flooding and erosion. By allowing water to permeate through the soil and vegetation, bio-swales and green roofs facilitate natural filtration processes that improve water quality before it re-enters the water cycle. This is crucial in urban environments where impervious surfaces prevent water absorption, leading to increased pollution and strain on drainage systems.

The use of such green infrastructure aligns with LEED's goals of promoting sustainable practices, enhancing ecosystems, and conserving water resources—key components of water efficiency and environmental responsibility in building design and construction. Additionally, while bio-swales and green roofs may offer aesthetic benefits and recreational spaces, their primary purpose is related to efficient water management and environmental health.