concepts · updated 2026-05-12
Water over air in radiant cooling
confidence: medium volatility: cold verified: 2026-07-19fresh
The archive's consistent preference for water over air as a thermal medium is not stated in one place — it is the cumulative conclusion of the Cool Cell brochure, the building thermal storage essay, t
The archive’s consistent preference for water over air as a thermal medium is not stated in one place — it is the cumulative conclusion of the Cool Cell brochure, the building thermal storage essay, the pool-heater cooling documents, and the night-sky experiments. The source filed here (response_to_baer.pdf) is a short handwritten note from Baer to Bruce W. Davis, dated July 8, 2000, commenting on the reception of the Corrales Comment irrigation column — not a technical document about radiant cooling. The water-over-air argument on this page is synthesized from the archive as a whole.
The archive’s water-over-air argument
Water over air is one of the archive’s most consistent themes:
| Medium | Storage capacity | Transport | Night-sky coupling |
|---|---|---|---|
| Air | Very low (1 BTU/ft³·°F) | Ducts, fans, electricity | Poor — requires large surfaces |
| Water | ~62× air by volume | Pipes, gravity, thermosiphon | Excellent — roof radiators cool water directly |
The Cool Cell system is built on this preference: water in ceiling reservoirs absorbs interior heat during the day, then circulates to roof-mounted radiators at night where it dumps heat to the sky. No compressor, no refrigerant — just water, gravity, and the temperature difference between a building and outer space.
The Corrales Comment note
The filed source (response_to_baer.pdf) is a personal note Baer wrote to Davis the day the irrigation column appeared: “Here’s my advice about engineering for slobs (like me — like us). Not a peep from anyone in response. I suppose most regard it as offensive.” The postscript mentions “more on H₂O… getting it straight out of our air” — a hint toward the desiccation satire that became Sunny days ahead.
The note is filed here because it is the only document in the archive dated the same day as the Corrales Comment, but it belongs more properly with the Corrales Comment page.