Ace the LEED Green Associate Exam 2026 – Go Green, Go Great!

The correct answer is timber from old-growth forests. Rapidly renewable materials are defined as resources that can be grown and harvested in a short time—typically within a 10-year cycle—allowing for a sustainable supply.

Bamboo, cork, and hemp all fit this definition as they can regenerate quickly, making them sustainable choices for construction and design. Bamboo can grow to maturity within a few years, cork can be harvested every 9 to 10 years from the same tree without harming it, and hemp grows rapidly, typically within 3 to 4 months.

In contrast, timber from old-growth forests comes from trees that have taken decades, if not centuries, to mature. By their nature, old-growth forests represent ecosystems that are significantly older and are not replenished quickly, making this type of timber unsustainable when considering the rapid renewable classification. Using materials from these forests raises concerns about environmental impact and sustainability.