Most GC's building track resi are in the volume business. Most buyers only know a few questions like what's the insulation rating or how long is the warranty. A GC can brag about the things they know will be asked and ignore the rest. Recent studies claim flex run in a unconditioned space can use 20-25% more energy. But it's cheaper than thinking a better solution. I once asked a large GC who always took the low number "How do you control quality?" He looked at me as if I had two heads.
On a brighter side there is a multi-state GC building homes here that works for high energy ratings. Apparently energy savings is selling for them. Until the customer demands a better building GC's will still dodge energy issues and distract buyers with granite counter tops. It's called by sales people as "Selling the sizzle instead of the steak."
I should have learned to play the g'tar on the MTV. MK