Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Where'd ya hear that one? Radiance's glass mat does take into account relectance, but if you want to specify a specific product, I'd recommend you use LBL's Optics program to create a glass and optional BRTDfuncs for the front and back sides of the glazing. It's been about ten years since I've done this so I don't have specific rendered examples handy, but I've done this extensively for precisely the kind of study you describe in your post. We'd create IGUs that match a given spec in Optics, and export to Radiance materials, apply, and render.
We also used a methodology where the two BRTDfunc definitions are merged with glazing.cal as discussed in this post, but if you're purely interested in the exterior appearance, you could just use the 'front' BRTDfunc you get out of Optics.
| | 2 | No.2 Revision |
Where'd ya hear that one? Radiance's glass mat does take into account relectance, but if you want to specify a specific product, I'd recommend you use LBL's Optics Optics program to create a glass and optional BRTDfuncs for the front and back sides of the glazing. It's been about ten years since I've done this so I don't have specific rendered examples handy, but I've done this extensively for precisely the kind of study you describe in your post. We'd create IGUs that match a given spec in Optics, and export to Radiance materials, apply, and render.
We also used a methodology where the two BRTDfunc definitions are merged with glazing.cal as discussed in this post, but if you're purely interested in the exterior appearance, you could just use the 'front' BRTDfunc you get out of Optics. Optics.
| | 3 | No.3 Revision |
Where'd ya hear that one? Radiance's glass mat does take into account relectance, but if you want to specify a specific product, I'd recommend you use LBL's Optics program to create a glass and optional BRTDfuncs for the front and back sides of the glazing. It's been about ten years since I've done this so I don't have specific rendered examples handy, but I've done this extensively for precisely the kind of study you describe in your post. We'd create IGUs that match a given spec in Optics, and export to Radiance materials, apply, and render.
We also used a methodology where the two BRTDfunc definitions are merged with glazing.cal as discussed in this post, but if you're purely interested in the exterior appearance, you could just use the 'front' BRTDfunc you get out of Optics.
Update 2018.04.12 Using your specific example Optics output, which looks like this:
void glass RefliteArcticBlue6mm_glass
0
0
3 0.160 0.179 0.131
void BRTDfunc RefliteArcticBlue6mm_front
10
0.555 0.561 0.478
0.147 0.164 0.120
0 0 0
.
0
9 0 0 0 0 0 0 0 0 0
void BRTDfunc RefliteArcticBlue6mm_back
10
0.121 0.236 0.275
0.147 0.164 0.120
0 0 0
.
0
9 0 0 0 0 0 0 0 0 0
You could use the RefliteArcticBlue6mm_glass definition for a single polygon. If you model both panes of the IGU though, I think you'd use RefliteArcticBlue6mm_front for both polygons; this way, renderings from either vantage point (outside looking at the building, or inside looking at the window) would be accurate. In the BRTDfunc case, you need to ensure the surface normals are facing the right way -- that is, the exterior lite facing out to the exterior, and the inner lite facing toward the interior. In the case of the glass def, the surface orientation does not matter.
Lastly, any of these three materials will work fine with Honeybee as they do not reference any cal files. Pretty sure Honeybee will work with cal files though, as it pretty much uses straight Radiance, and as long as you have a properly installed Radiance setup, it all should work.
