What is true regarding a material’s emittance and albedo?

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试卷: LEED GA模拟题E[查看]
What is true regarding a material’s emittance and albedo?
A: Emittance is based on a material’s albedo
B: Emittance and albedo are used to calculated a materials perviousness
C: Emittance and albedo are combined to determine a material’s SRI value
D: A material’s emittance and albedo mean the same thing

参考答案: C

本题解释:
Notes:

Reference: LEED for Existing Buildings: Operations & Maintenance Reference Guide, Glossary
A:This is not correct. See the definitions in this explanation for albedo and emittance.
B:These values are not used to calculate how pervious a material is.
C: SRI is calculated by using emissivity and albedo values.

Solar Reflectance Index (SRI) indicates a materia’s ability to reject solar heat and is the combined value of reflectivity and emittance. Measurements vary from 100 (standard white surface, most reflective) to 0 (standard black surface, least reflective). Materials with the highest SRI values are the coolest choices for paving.

The higher the SRI number the more the sunlight the material can reflect. Black asphalt has an SRI of 0.
D:Albedo (or solar reflectance) is a material\'s ability to reflect sunlight measured on a scale of 0 (black) to 1 (white). A value of 0.0 indicates that the surface absorbs all solar radiation and a value of 1.0 represents total reflectivity.

The emittance of a material refers to its ability to release absorbed heat. Scientists use a number between 0 and 1, or 0% and 100%, to express emittance. With the exception of metals, most construction materials have emittances above 0.85 (85%). Emittance is used by manufacturers to calculate the SRI.