LEED AP with Operations and Maintenance (O+M ) Practice Exam

Which of the following factors is essential for calculating the effectiveness of a vegetated roof?

1. Area coverage and growth type

2. Material used in construction

3. Maintenance frequency

4. Water retention capacity

The correct answer is: Area coverage and growth type

Calculating the effectiveness of a vegetated roof involves evaluating several key aspects that contribute to its performance in terms of environmental benefits, thermal comfort, stormwater management, and overall aesthetics. The area coverage and growth type are essential factors since they directly affect the roof's ability to provide insulation, retain water, and promote biodiversity. The area coverage refers to the extent of the roof that is vegetated. A larger area coverage typically means better water retention and increased benefits related to temperature regulation and habitat creation. The growth type—whether it consists of sedums, grasses, or other plant species—also determines how well the vegetated roof performs under varying environmental conditions. Different plant types have differing water uptake, drought resistance, and maintenance needs that can impact overall effectiveness. While material used in construction plays a role in the structural integrity and longevity of a vegetated roof, it does not directly determine its effectiveness concerning the ecological and performance benefits the vegetation itself provides. Maintenance frequency is important for the longevity and health of the vegetation but is not a primary factor in assessing the initial effectiveness. Water retention capacity is critical, but it can be influenced by the area coverage and growth type. Thus, understanding both area coverage and growth type provides a more comprehensive measure for the overall effectiveness