Hi,
As per Table G3.1?5(c), the roof surface should be modelled with a
reflectance of 0.45 if the reflectance of the Proposed roof is greater than
0.7 and its emittance is greater than 0.75. Otherwise, the Proposed
reflectance should be 0.3. The Baseline roof should be modeled with a
reflectivity of 0.3.
In EQUEST, we can put Ext. Absorptance and not reflectance.
What is the relation between reflectance and absorptance and for base line
reflectivity of 0.3, what absorptance value should I put?
Rakesh
Absorptance + transmittance + reflectance = 1
Since it is an opaque structure, transmittance = 0 and absorptance = 1 - reflectance = 1 - 0.3 = 0.7
Hope this helps.