Bare aluminum shutters below ceiling water storage, tested in the Andy Shack (March 2001). They control radiant heat flow from 8″ PVC pipes on 12″ centers to the room below — open for heat delivery, closed for heat banking. The source calls them "very effective" and reports a 4–5× difference in heat transfer rate between open and closed states.
The Andy Shack is a Zomeworks test building in the Albuquerque yard, in use since 1988. The June 2000 configuration used as the baseline for the shutter experiments:
Data from the Andy Shack, March 2001:
| Condition | Room temp | Pipe temp | Outside temp |
|---|---|---|---|
| Shutters closed | ~60°F | ~90°F | ~45°F |
| Shutters open | 75–80°F | ~90°F | ~45°F |
Baer derives the conductivity ratio from these temperatures:
The reflective aluminum provides an estimated R-value of 4–5 when closed. Despite "huge long cracks between the shutters," warm air does not leak down in winter — "it doesn't want to" (warm air rises).
The shutters behave differently by season:
This asymmetry is actually helpful: "Coolth does not need to be stored in such large amounts as heat. Night is certain to recharge coolth every 24 hours; the sun is not so reliable." The system naturally holds heat tightly (winter need) and releases coolth freely (summer need).
Sample ceilings with 9 one-liter Coke bottles per square foot transferred 3.75 BTU/°F·ft²·hr — even better coupling than the pipe arrangement.
Shutters are silent and passive; radiant heating and cooling is always pleasant.