I scanned for errors before calculating and was told that '1 construction(s) have roof surfaces with a noncompliant solar absorptivity specified?' Apparently, 4 inch LW Concrete has an outside shortwave (solar) absorptivity equal to 0.90 but should be modeled as 0.70. How can I change the solar absorptivity?
After reviewing this closer, I realized that the error was due to the fact that my baseline design had a roof construction that was non-compliant with ASHRAE standard 90.1. It was a matter of simply changing the roof construction from 4 inch LW Concrete to 90.1-07 Min Roof Res Zone 1-8 under the Roofs tab in Create Rooms. You will not get the same error with your proposed building design.
Also, if you are having a hard time trying to find out what your actual outside shortwave (solar) absorptivity [OSSA] is, go to your Construction Types Library. It will show you the different layers of materials and their associated thicknesses, conductivities, densities, specific heats, and resistances (R-values). You will not see the OSSA, so you have to click on the advanced box. The Advanced Envelope Parameters window will open which displays values for OSSA, Outside Longwave (thermal) Emissivity, Inside Shortwave Absorptivity, Inside Longwave (thermal) Emissivity, Inside Visible (hemispherical) Reflectance, and a dropdown box with various options for the Exterior Roughness (used fro outside film calculation).
This is all for version 6.0 of Trane Trace 700.
Hope this can be of some help to anyone.