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.

• Alternative Building Practices: We used a re-enforced and concrete filled block wall on the interior of the structure, opposite the south wall. This wall is part of the heat storage system, but also acts as a structural shear wall, a common requirements in most new construction. Block construction is a common technique but seldom used for such an application. As such, this type of work can't be done on 'auto pilot', it requires extra planing and organization and a more versatile construction crew. And all that costs more.

All of this demonstrates that passive solar construction is more expensive than conventional construction. It is more expensive because:

1. It is unusual and non standard.
2. It requires more architectural/design work.
3. It requires some non-standard materials and techniques.

At a minimum, passive solar construction costs 10% more than conventional construction. But good planing should help keep these costs under control.