Harold Hay, Skytherm, and the Quest for Passive Cooling

Publication: Architect Magazine
Date: December 11, 2020
URL: https://www.architectmagazine.com/technology/harold-hay-skytherm-and-the-quest-for-passive-cooling_o
Access: 403 — article text not captured. Content below is synthesized from accessible secondary sources.

Secondary sources consulted

Mother Earth News — Plowboy Interview with Harold R. Hay (1976)

Primary interview with Hay. Key content:

Background: Born 1909, Spokane, WA. Career in chemistry — wood preservation (pentachlorophenol at Monsanto), municipal water purification. Government of India adviser on low-cost housing.

Sky-Therm system description: “No pumps, no fans, no circulating liquids, no freezeups, no boil-overs, no trouble, no noise, no dirt.” Water bags on roofs + movable insulating panels. System maintained comfort at 106°F exterior temperatures; above 115°F required small fan assistance. Adaptable to climates from equator to Arctic.

“Cool black and warm white” theory: Surface thermal properties depend on insulation layers. Tropical animals have dark coats because they need to radiate heat outward; polar bears are white because they need to absorb heat. Same principle governs roof behavior.

Philosophy: Design “with the climate” rather than overwhelming it with energy consumption. Criticized centralized solar (satellites, desert collectors with transmission lines) as polluting; favored distributed roof-level systems.

On Baer and peers: Hay referred to Steve Baer, Harry Thomason, and similar figures as “creative activists” — individuals who “took their own time and money and worked with their own hands to develop solar energy systems that work.”

Timeline from interview:

First experimental house: India, 1954 — movable insulation panels
Arizona test house on John Yellott’s property
1973: Atascadero, California full-scale house

Browning Day — “The Invention of the Roofpond System”

Technical history. Key content:

India (1952): Hay served as adviser to the Government of India on low-cost housing. Observed that replacing thatch roofs with uninsulated asbestos-cement reduced comfort. Developed “Growing House” concept using manual movable insulation on roofs and masonry walls.

Arizona (1966–67): Experiments with 7-inch deep water basins in Tempe. Established that 6 inches of water provided adequate year-round thermal storage.

Phoenix Prototype (1967) — specifications:

120 sq ft test structure
Three 4×8 ft movable polyurethane insulation panels (1.5” thick, 125 lbs each)
Three roof bays with 6–7” water bags under 10-mil black polyethylene liner
Manual operation via nylon clothesline, hand winch, pulleys
Vermiculite-filled lightweight concrete block walls
Carport for storing retracted insulation panels
Co-developed with John I. Yellott (passive solar engineer, Arizona State University)

Performance (Phoenix prototype):

Interior 70–80°F during 91% of annual hours
Daily temperature swings: 4–8°F (extremes: 2–12°F)
Required fan-coil cooling only during three summer months when outdoor temperatures exceeded 110°F

Hay quote: “Water is the cheapest and most efficient heat storage material for buildings. Its fluid convection provides an outstanding advantage over the heat lag of solar materials.”

Vindy Archives — “Heating, Cooling with the Sun” (November 25, 2007)

Profile of Hay at age ~98. Key content:

Atascadero house (1973): 1,100 sq ft full-scale. Plastic waterbed-like bags. No pumps, compressors, piping, or ducts. Indoor 68°F–72°F vs 32°F–68°F outdoor.

Timeline:

1967: Phoenix test home
1973: Atascadero prototype complete
1974: Testified before Congress
1976: American Revolution Bicentennial Commission — one of America’s 200 most promising inventions
Cal Poly: Hay donated house + $1 million for research; periodically revived

Key quotes:

“You don’t need electricity to cool! You don’t need an air conditioner! You do it with the sky.”
“My house was one of the unique things, and it’s gone nowhere.”
Ken Haggard (solar architect): “He’s a caricature of the mad inventor. He’s a genius. But he’s also impossible. And he has not mellowed one iota.”
Becky Campbell-Howe (American Solar Energy Society): “His invention and what he’s been saying for all these years is still very, very relevant…the main point…is that it’s not that complicated.”

Misfitsarchitecture.com — “Night Sky Radiant Cooling” (March 1, 2013)

Direct Hay-Baer technical comparison:

Hay’s system: Water bags on roof + movable insulating panels. Panels closed during hot days (deflecting heat while drawing warmth from interior); retracted at night to release heat skyward. Winter reversal. Atascadero used plastic waterbed-like bags. System operated for ~40 years without electricity.

Baer’s system (per this source): Water wall (55-gallon drums) behind south glazing with insulated reflective covers. Later: Double Play — absorber panels on south wall, water storage in ceilings, radiator/cooling coils on roofs. Research showed only 25% cooling reduction with vertical vs horizontal radiators.

Performance comparison:

Night sky radiant cooling: 90–95% less energy than air conditioners; 65–80% less than evaporative coolers

Key academic source — Steve Baer on Hay’s influence

Book: Activism in Architecture: Bright Dreams of Passive Energy Design
Editors: Margot McDonald and Carolina Dayer
Publisher: Routledge (Taylor & Francis), 2018
ISBN: 978-1-138-74143-0 (hardcover), 978-0-367-66567-8 (paperback)

Chapter 4: “Harold Hay’s influence and the Zomeworks Corporation” — authored by Steve Baer

This is the primary documentary source for the Hay-Zomeworks connection. Baer wrote the chapter himself, placing Hay as an acknowledged influence on his own work. Text is not publicly accessible; citation confirmed via Taylor & Francis catalog. The book also contains:

Chapter 12: “Untapped potentials in Harold Hay’s roof pond system for passive heating in cold climate regions” — Daniel Overbey
Chapter 15: “Resilience as a driver of passive design” — Alex Wilson

Google Books preview (partially accessible) confirms the book discusses Sunbenders as “still available from Zomeworks.”