This report, from the CEPHEUS project, should change your mind about many aspects of homebuilding.
I'll try to boil down the most important points in the report in regard to green building in Denver and Colorado:
1. If the walls are superinsulated, if excellent windows are used, and air infiltration is minimized, there may be no need for a heating system per se.
2. A house this tight does need ventilation, and a good way to precondition this air is through a buried tube. The common fear of mold in this tube shouldn't be a problem in Colorado.
3. An 80% effective air to air heat exchanger should be employed to recoup the heat from the stale air being exhausted from the house.
4. Eliminating the thermal bridging commonly seen in stud walls is highly important.
5. A superinsulated home automatically means a very uniform temperature distribution, and increased comfort.