Learn the most effective roof coverage strategy to mitigate both heat island effect and rainwater runoff according to LEED standards. Boost your LEED Green Associate Exam prep with expert insights.
Table of Contents
Question
Which strategy for roof coverage best addresses both heat island effect and rainwater runoff from the roof only?
A. 100% vegetated
B. 100% high-albedo
C. 20% high-albedo and 80% conventional
D. 50% standing seam copper and 50% vegetated
Answer
The best strategy for roof coverage that addresses both heat island effect and rainwater runoff from the roof is:
A. 100% vegetated
Explanation
A 100% vegetated roof coverage best addresses both heat island effect and rainwater runoff from the roof only. A vegetated roof, also known as a green roof, is a layer of living plants that covers the roof surface.
A vegetated roof reduces the heat island effect by providing shade, evapotranspiration, and insulation, lowering the roof temperature and the surrounding air temperature. A vegetated roof also reduces rainwater runoff by retaining and absorbing precipitation, decreasing the volume and peak flow of stormwater leaving the roof.
The other options are not as effective as a 100% vegetated roof coverage in addressing both heat island effect and rainwater runoff from the roof only. A 100% high-albedo roof reflects more solar radiation than a conventional roof, reducing the heat island effect, but it does not reduce rainwater runoff.
A 20% high-albedo and 80% conventional roof has a lower reflectance than a 100% high-albedo roof, resulting in a higher heat island effect, and it does not reduce rainwater runoff either. A 50% standing seam copper and 50% vegetated roof has a lower vegetated area than a 100% vegetated roof, resulting in less shade, evapotranspiration, insulation, retention, and absorption, leading to a higher heat island effect and more rainwater runoff.
A vegetated roof, also known as a green roof, offers the most comprehensive solution for mitigating both heat island effect and rainwater runoff. Here’s why:
- Heat Island Effect Reduction: Vegetated roofs help reduce the heat island effect by absorbing less heat and reflecting more sunlight compared to conventional roofing materials. The plants and growing medium on the roof act as a natural insulation layer, keeping the roof surface cooler and reducing the amount of heat transferred to the building interior.
- Rainwater Runoff Management: Green roofs are highly effective in managing rainwater runoff. The plants and growing medium absorb and retain a significant portion of the rainwater, reducing the volume and rate of runoff from the roof. This helps to mitigate the strain on stormwater infrastructure and minimize the risk of flooding and water pollution.
In contrast, while high-albedo (reflective) roofs are effective in reducing the heat island effect, they do not address rainwater runoff. A combination of high-albedo and conventional roofing materials (Option C) or standing seam copper and vegetated roof (Option D) may partially address both issues but not as effectively as a 100% vegetated roof.
Therefore, a 100% vegetated roof (Option A) is the most comprehensive and effective strategy for addressing both heat island effect and rainwater runoff from the roof.
USGBC LEED Green Associate certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the USGBC LEED Green Associate exam and earn USGBC LEED Green Associate certification.