By the time we were selecting the floor tile, our budget indicated a need to "tighten our belts". So I brought a few darker colored floor tile samples to the Van Horne and Van Horne offices. We placed the tiles on a sunny window sill. After a few minutes we removed the tiles from the sill and used some of our sophisticated testing equipment (our hand) to determine which tiles were warmer and retained heat for a longer period of time.
The winning sample was a 3x6 matt glazed tile that was light brown in color. It was also one of the least expensive samples - what luck!
And now, 20 years later, this same tile is in excellent condition! A much better condition than that of the bathroom vinyl or carpeted floors.
All of this demonstrates that passive solar construction is more expensive than conventional construction. It is more expensive because:
At a minimum, passive solar construction costs 10% more than conventional construction. But good planing should help keep these costs under control.