Solar Fool KB — Glossary

Definitions of key terms across the Solar Fool Knowledge Base: devices, buildings, organizations, publications, concepts, and frameworks from the Steve Baer / Zomeworks passive-solar archive (1968–2025). Alphabetically sorted, 140 entries.

31-zone star: A structural system based on 31 lines through the center of an icosahedron (6 A-lines through vertices, 10 B-lines through dodecahedron vertices, 15 C-lines through edge midpoints), yielding 121 distinct planes and 242 faces. The geometric foundation of Baer's zome structural patent (US 3,722,153) and the Zometool construction kit.

Air loop rock storage: A convective, fan-free heating system using south-facing solar collectors, river rock thermal mass, and natural air convection. Baer built the earliest known working example at Drop City (c. 1967–68) using salvaged car rear windows as collectors, and documented the design in Sunspots with a 15-rule practical guide.

Alloy Conference: A spring 1969 gathering organized by Steve Baer, Holly Baer, and Barry Hickman that directly preceded the founding of Zomeworks Corporation. Location disputed between Alamogordo, NM and near Drop City, CO.

Aluminum rolled formed roof: A Zomeworks construction method where roll-formed aluminum roofing grips copper pipes spaced 8″ on center, making the roof both a weather surface and a thermal collector/radiator without glazing or special equipment. A key component of the Cool Cell and di-thermal roof systems.

Analemma: The figure-eight traced by the sun's noontime position over the course of a year, resulting from Earth's 23.5° axial tilt and its elliptical orbit. The visual signature of the perihelion effect.

Andy Shack: A 10 ft × 10 ft Zomeworks test cabin built in 1988, with 250 gallons of water in PVC ceiling pipes, a 65 sq ft copper roof radiator, and aluminum louvers below. The long-running testbed for overhead thermal shutters and the experimental precedent for the Double Play thermosiphon system.

Avoided-cost model: A billing method for thermal-as-a-service contracts, where the fee is based on what the building owner would have paid for conventional cooling rather than on directly metered thermal output.

Baer House: Steve Baer's own house in Corrales, New Mexico, built 1971–72 as a cluster of eleven zomes totaling roughly 1,900 sq ft (185 m²). The first full-scale testbed for DrumWall, Skylid louvers, and Sunbender reflectors, and the physical origin of a 30-year patent sequence.

Battery cabinets (passive): Night-sky-cooled enclosures developed by Zomeworks for telephone company equipment at remote sites. Thousands of units were sold, constituting about 70% of Zomeworks sales for several years. Covered by US Patents 4,913,985 (1990), 5,070,933 (1991), and 5,316,872 (1994). The archive's hidden commercial validation of passive thermal technology.

Beadwall: A window insulation system invented by Dave Harrison of Zomeworks. Polystyrene beads are pneumatically blown into the cavity between two panes of glass when insulation is needed and sucked back out when solar collection is wanted, making the window's thermal properties switchable. US Patent 3,903,665 (1975).

BigFins: Aluminum night radiators referenced in John Solso's Double Play experiments in Tucson, intended for mounting on west-facing roofs to radiate heat to the night sky and, in winter, absorb solar heat.

Boogie valve: A floating plastic check valve used in Zomeworks' di-thermal wall experiments, named by Joe Minella because the plastic balls could be seen "boogieing" through clear pipe. Evolved from Shawn Buckley's oil-on-water fluidic check valve concept.

Bridgers & Paxton: An Albuquerque engineering firm that built the 1956 Solar Building, widely called the world's first solar-heated commercial office building. SAH Archipedia places it as the predecessor to Baer's 1971 house in New Mexico's passive-solar lineage.

Bruce Davis Studio: A 236 sq ft detached studio in Albuquerque fitted in 2003–04 with 12 roof pig mats and 38–42 vertical PVC water pipes as a Double Play demonstration. Interior held 73.5–78°F while ambient swung 58–94.5°F. The most thoroughly documented thermosiphon installation in the archive.

Building thermal storage: The principle that energy storage within the building envelope — specifically water — is a basic building function, not an optional add-on. Baer: "The addition of energy storage to buildings is of utmost importance whether we plan to use power plants or nature."

Can brick: A building block patented by Mike Reynolds in 1973, made from recycled beverage cans. His first construction-material invention, preceding the rammed-earth-tire Earthship.

Comfort argument: The rhetorical shift between the 1973 and 2002 archive phases: early work argues from physics, while the later Cool Cell documents argue from radiant comfort and simplicity. The archive learned that physics alone does not sell buildings.

Comfort-framed messaging: A Passive House Institute strategy that pivots from technical performance metrics to occupant experience language, making passive thermal technology accessible to non-experts.

Cool Cell: Zomeworks' passive architectural climate-control system using water reservoirs in the ceiling connected to roof-mounted radiator/absorbers. In summer, water circulates at night via thermosiphon to dump heat to the sky; in winter, a small pump reverses the cycle for heating. No refrigerants, no compressor. US Patent 6,357,512 B1 (2002). The engineering descendant of Harold Hay's Skytherm.

Coolth: Stored cooling capacity — the cold-side analog of stored heat. In the archive's systems, water stores coolth at night via sky radiation and releases it during hot afternoons.

Creative activists: Harold Hay's term for independent practitioners like himself, Steve Baer, and Harry Thomason who "took their own time and money and worked with their own hands to develop solar energy systems that work" — working outside government funding.

Cumba: An irregular room element in traditional Turkish architecture that floats over the street, channeling breezes, capturing sunlight, and framing vistas simultaneously. Cited by John Solso as a historical example of the "double play" multipurpose design principle.

Demand-destruction theory: Baer's explanation for why passive solar interest comes in recurring waves that recede: passive systems reduce energy purchases, so fossil fuel sellers have a structural incentive to suppress each wave.

Demonstration project theater: A critique of isolated showcases that reach "a self-selecting population of people who are probably already into such things" rather than proving a technology's worth to skeptical, unconverted visitors.

Di-thermal roof: An unglazed roof surface that does double duty: collects solar heat during winter days and rejects heat to the night sky on summer nights. Only possible because the collector is unglazed — glazing blocks efficient radiation to the sky. Conceptually traced to Farrington Daniels' 1964 observation that collectors should be uncovered for nocturnal radiation cooling.

Di-thermal wall: A Zomeworks prototype wall system using boogie valves to passively manage heat flow between interior and exterior thermal zones. The predecessor design before Baer switched to overhead ceiling tanks in August 1999.

Direct Use of the Sun's Energy: The canonical pre-oil-crisis survey of solar energy by Farrington Daniels (Yale University Press, 1964). Surveys all known methods of solar energy use, documents Bliss's nocturnal radiation cooling experiments, and records cooling rates of 10–35 BTU/ft²/hr.

Diving engine: Baer's gravity-engine design using two weighted floats ("divers") in separate hot and cold liquid baths connected to a flywheel, with air passing through a regenerator. Operates at roughly constant pressure (like an Ericsson engine). Baer built a working prototype running at 4–6 rpm.

DOE Solar Decathlon: A biennial student solar-house competition launched by the US Department of Energy in 2002 on the National Mall. Rebranded "BuildingsNEXT" in March 2025. Critiqued as demonstration-project theater.

Dome Cookbook: Steve Baer's 1968 publication documenting dome and zome construction techniques, published by the Lama Foundation. It influenced Stewart Brand's publishing approach for the Whole Earth Catalog and Lloyd Kahn's Domebook One.

Double Play: Zomeworks' heating and cooling system where a single roof element serves dual thermal functions: collecting solar heat in winter and radiating heat to the night sky in summer, circulating water between roof radiators and ceiling-mounted storage. The term was generalized by John Solso to mean any design element serving multiple functions.

Dover Sun House: A 1948 solar house in Dover, Massachusetts built by Maria Telkes, Eleanor Raymond, and Amelia Peabody. Its Glauber's-salt heat-storage system received massive press coverage but failed within three winters due to salt stratification and container corrosion.

Drop City: A counterculture commune near Trinidad, Colorado, founded in 1965. The origin point for Steve Baer's zome structures and the site of his first working convective air loop rock storage system (c. 1967–68). Received a $500 Dymaxion Award from Buckminster Fuller. Abandoned by 1973.

DrumWall: Steve Baer's original passive solar invention: a south-facing wall of water-filled 55-gallon drums (450 lbs each) behind glazing, absorbing solar heat during the day and radiating it into the room overnight. Originating at Drop City (c. 1968), first installed at full scale in the Baer House (1971).

Earthship: A sustainable, off-grid building type developed by Mike Reynolds using rammed-earth tires as structural thermal mass. An estimated 3,000 exist worldwide as of 2025. SAH Archipedia places it as the successor to Baer's house in New Mexico's passive-solar lineage.

E-folding and thermal time constants: The mathematical framework for passive thermal systems: thermal processes decay exponentially, with each time constant removing ~63% of the remaining temperature difference. Baer's essay argues this concept — rather than linear thinking — is essential for understanding how buildings gain and lose heat. Baer: "5, 4, 3, 2, 1, 0, (blast off); Nature's pace: 5, 4.09, 3.35, 2.74, 2.246, 1.84 (oops)."

Energie Solaire: A Swiss manufacturer of selective-surface stainless steel solar absorbers. Baer tested their unglazed absorber and found it could "stagnate above boiling with no glazing on a cold, partly cloudy, breezy November day," outperforming the glazed version up to 36°F above ambient.

Epidemic metaphor: Baer's framing of passive solar interest as recurring waves that fossil fuel industries work to suppress: "Those who sell gas, electricity, propane and oil may regard these periods of self reliance and clever designs as epidemics which weaken the demand for their power and fuels."

Familiarity barrier: A market obstacle: builders default to systems they know (forced-air, compressor-based), and old moisture-control failures in early radiant systems created lasting distrust.

Fifty-watt dog: A pedagogical device from Sunspots: a human on a 1,000-calorie diet runs at about 48 watts continuously. "It makes sense to let the dogs inside on a cold night, not just for their sake, but to help heat the house."

Franchise vision: Baer's 2004 plan for scaling passive thermal deployment through trained regional teams equipped with roll-formers to produce di-thermal roof panels locally.

Franklin pulse-glass: A novelty thermometer invented by Benjamin Franklin that uses the same vapor-pressure liquid-transfer mechanism as the Skylid. Prior solar applications include Brodie's Wig-Wag instrument (1929) and Geer's heliotropic device (US 2,999,943, 1959).

From Counterculture to Cyberculture: Fred Turner's 2006 academic history tracing how Stewart Brand bridged 1960s–70s countercultural communities and Bay Area computer-research institutions. Documents Steve Baer's direct place in the counterculture-to-computing network.

Geodesic dome: A spherical structure of interconnected triangles, developed by Buckminster Fuller. Baer explicitly departed from the form: geodesic domes are "complicated in structure and simple in shape" while zomes are "simple in structure and complicated in shape."

Ghost Ranch: A location in Abiquiu, New Mexico where NMSEA was co-founded in 1972 and where the Sun-dwellings passive-solar test units were later built.

Glauber's salt: A phase-change heat storage medium (sodium sulfate decahydrate) used in the Dover Sun House. It stratified over repeated cycles and its containers corroded, causing system failure — an early cautionary tale for non-water thermal storage.

Gnomon: A tool with a bull's-eye and shadow-casting rod, proposed by Baer as a field instrument to reveal the orientation efficiency of solar collectors relative to the sun.

A Golden Thread: Ken Butti and John Perlin's 1980 history of solar energy. Notable as negative evidence: its 289 pages never mention Steve Baer, Harold Hay, Harry Thomason, or the counterculture practitioners — the historiographical gap that helped ensure their work remained invisible.

Gravity engine: In Baer's definition, any engine that relies on gravity to function — a device like a hydroelectric plant or windmill where gravity acts as "a spring that doesn't wear out." The Skylid is "a very simple example of a gravity engine."

Hagen-Poiseuille law: The fluid dynamics principle relevant to thermosiphon scaling: friction losses in a pipe scale as 1/D⁴ for a given flow rate, meaning reducing pipe diameter increases friction far faster than shrinking buoyancy head can compensate.

Heated vs. unheated plates: Experiments by Stickney and Baer (October 2002) proving that on clear New Mexico nights, a horizontal plate with 9.5 W/ft² of electric heat cannot reach ambient air temperature — the sky pulls heat away faster than the heater supplies it. Numerical grounding for night-sky radiative cooling.

Herding: A failure mode in demonstration-driven adoption: a project gets copied without genuine knowledge transfer, propagating underperforming technology rather than real learning.

Historiographical gap: The systematic absence of counterculture passive solar innovators (Baer, Hay, Thomason) from canonical solar energy histories, ensuring later researchers would not find these approaches.

Hydronic radiant cooling: Cooling by circulating chilled water through ceiling, wall, or floor panels. Energy savings of 25–42% over variable-air-volume systems. Helmut Feustel (LBNL) called it "the new standard" in Germany.

Ice Ranch: Baer's proposal to harvest at least 6 feet of ice per year from Albuquerque ponds, producing ice at $0.01/lb versus $0.15/100 lbs from electric production.

Information deficit model: The theory that public skepticism stems purely from missing facts — that supplying information will convert attitudes. The literature finds knowledge alone rarely shifts behavior. A direct caveat on passive-solar pedagogy.

Infrared scanner / IR thermometer: Baer's preferred measurement instrument, a $30 device whose "stream of questions for its user becomes a Sunman's education." The starting point of the archive's teaching method: hand someone an IR thermometer and send them to a parking lot.

Institutional definition problem: How the official definition of "passive cooling" was established without water-based night-sky approaches. The USAF Passive Solar Handbook defined passive cooling as only air-based strategies, propagating this omission across hundreds of bases worldwide.

Integral Roof Cooling Container: Dave Harrison's patent (US 5,609,200, 1997) for water-filled containers rotationally molded onto metal roof sections that cool by night-sky radiation. Bridges battery-cabinet patents and the Cool Cell.

Karen Terry House: A passive solar house in Santa Fe (1974), the second passive solar house built in New Mexico. Designed by David Wright (adapting his Sunscoop) and built by Karen Terry herself with one helper over nine months. Compact multilevel design of less than 1,000 sq ft with no mechanical backup.

Lama Foundation: An interfaith spiritual community near San Cristobal, NM, founded in 1967. Published Baer's Dome Cookbook through its "cookbook fund" and hosted Ram Dass while he assembled Be Here Now. Still active as of 2026.

Libre: An intentional community in Gardner, Colorado, co-founded in 1968 by Peter Rabbit and Dean Fleming after leaving Drop City. Described as the oldest continuously operating hippie commune in the country.

Local network learning: The mechanism by which demonstrations actually drive adoption: people watching their neighbors, not reading national press. Local green-building adoption rates roughly double after a nearby project's completion.

Market failure (passive thermal): The synthesis finding that the absence of mainstream adoption is not a technical failure but a market failure: passive systems eliminate ongoing energy purchases, removing the economic incentive for utilities, HVAC manufacturers, and large builders to deploy them.

Measurement gap: Most decision-makers have never looked at a building with an infrared camera or measured a surface temperature. The thermal world is invisible to them, so they cannot demand what they have never experienced.

Movable insulation: Insulating panels that can be repositioned to manage heat transfer seasonally. Harold Hay developed the concept starting with his 1954 "Growing House" in India. Baer called it "Harold Hay's revolutionary solution to house comfort."

Naturally-cooled slab floor: A design where naturally cooled water (from evaporation or night-sky radiation) circulates through tubing in concrete slab floors, making the floor itself a cooling delivery system and thermal mass.

New Communalism: Fred Turner's term for the back-to-land/commune movement of the 1960s–70s, distinct from the political New Left. Turner positions Zomeworks as a New Communalist organization. Kayatekin's 2025 paper traces the thermal vision's development within this tradition.

New Mexico Solar Energy Association (NMSEA): A solar-education nonprofit and NM chapter of ASES, co-founded at Ghost Ranch in 1972 by Keith Haggard, Peter Van Dresser, and Steve Baer. Publishes the SunPaper newsletter and runs the Solar Fiesta and Sun Chaser educational programs.

Night-sky radiative cooling (NSRC): The process by which surfaces cool by radiating infrared energy directly to space through the atmosphere's infrared window. Baer: "Does cold air cool the ground at night? No, it is the other way around; the air is cooled by contact with the ground, which first cools itself by shining heat into space." Documented at 10–35 BTU/ft²/hr by Daniels (1964). Performance drops sharply with humidity.

Night-sky reversal: The pedagogical moment when common intuition is overturned: the ground cools the air at night (by radiating to space), not the other way around. The second step in the archive's teaching sequence after the IR thermometer demonstration.

Nightwall: Rigid foam pressed against glass for window insulation. The simplest of Zomeworks' three window insulation approaches (Beadwall, Nightwall, Skylid), with no moving parts.

NSRC Report: A 2006 New Mexico state-funded field study by Mark Chalom, Bristol Stickney, and Kate Snider for Governor Richardson's Water Innovation Fund. Tested 10 radiator panel types over two summers at 6,800 ft elevation. Found NSRC could cool an 1,800 sq ft home in every NM climate zone, with 25–89% power savings versus conventional cooling. The strongest independent evidence in the archive.

Osmotic heat pipe: A heat pipe using osmotic pressure for condensate return, designed by Baer for zero-gravity environments. US Patent 3,561,525 (1971). Never built — Baer was "ashamed to say I never once tried out the idea."

Overhead thermal shutters: Bare aluminum louvers installed below ceiling water storage that control radiant heat flow to the room. When open, heat transfer quintuples. They exploit a natural asymmetry: in winter warm air does not leak down; in summer cool air naturally falls through, favoring free cooling delivery.

Passive House Institute (PHI): An international building-performance standard and certification network. Its most successful scaling case (Massachusetts: 2,500 units built, 35,000 in pipeline) combined comfort-framed messaging, institutional bulk deployment, and community technical support — a validated analog for thermal-as-a-service.

Peradam: A 1969 three-day gathering near Santa Barbara bringing countercultural organizations (including Zomeworks) into contact with Stanford Research Institute researchers, placing Baer in direct contact with the computer-research world in Zomeworks' founding year.

Perihelion: The point in Earth's orbit closest to the sun (early January), making winter sunlight ~7% stronger than at aphelion (early July). For unglazed collectors operating at small temperature differences, this boost partly explains why Baer's shower worked through "icy January weather." Drifts later by about one day every 57 years.

Pig mat: Black polypropylene mats used as rooftop radiator/absorbers in the Double Play system. Twelve pig mats (127 sq ft) were used on the Bruce Davis Studio roof.

Pilotisation: UK Green Building Council term for demonstration projects built to generate PR without a defined route to portfolio-wide adoption. Their conclusion: "the sector doesn't need more isolated pilots, it needs coordinated action to bring proven solutions into mainstream use."

Pool-heater cooling: Baer's retrofit strategy of repurposing existing swimming-pool solar collectors as night-sky radiators to cool buildings. 400 ft² of radiator provides the same 60,000 BTU cooling as a one-ton A/C unit. Described as harvesting a "second crop" from already-paid-for hardware.

Qanat: Ancient Persian underground water canals that fed surface channels in yakhchal ice-production systems. The water froze overnight in shaded channels protected by high walls.

Radiant comfort: Direct warming or cooling of occupants by infrared radiation from building surfaces, rather than forced air. Radiant heat reaches occupants at the speed of light regardless of air currents. The archive's bet: "Physics convinces engineers. Comfort convinces everyone else."

Regenerator: A thermal-storage element in heat engine design that captures heat from gas moving toward the cold side and returns it on the way back. Used in Baer's diving engine.

Relative thermostat: The Skylid's operating principle: paired refrigerant canisters compare temperatures between inside and outside rather than acting at a fixed set-point — "exactly what's needed for solar control."

Retrofit-first: The archive's recurring deployment strategy: attach passive thermal systems to things that already exist — existing pool heaters, existing roofs, existing building shells — rather than requiring purpose-built novelty.

Rhombic triacontahedron: The standard zome unit — a 6-zone, 30-face zonohedron with 20 cells. Two triacontahedra fuse through a shared skew hexagon; the Baer House is a cluster of connected triacontahedra.

RISA (Roof Integrated Solar Absorber): An "invisible" solar collector built into the roof structure with a thermal absorber under the weatherable surface. Developed by FSEC/NREL (1998–2000). Trades efficiency for aesthetics: a glazed collector is 10–15× more efficient per unit area.

Roll-former: Metal-forming equipment central to Baer's franchise vision: regional teams would produce di-thermal roof panels locally.

SAH Archipedia: The Society of Architectural Historians' online encyclopedia. Places the Baer House in a lineage: Bridgers & Paxton Solar Building (1956) → Baer House (1971) → Reynolds' Earthships.

Selective surface: A coating engineered for high solar absorptivity but low infrared emissivity — allowing efficient heat collection without glazing. The physics underlying unglazed solar collector performance. Credited to Harry Tabor.

Shelter: Lloyd Kahn and Bob Easton's 1973 book pivoting from geodesic domes to global vernacular building after Kahn concluded domes "did not work as homes."

Skylid: Zomeworks' insulated skylight louver that opens and closes using vapor-pressure-driven refrigerant transfer between paired canisters — no electricity, no thermostat, no motor. US Patent 3,884,414 (1975). R-value ~5 closed, opens at least 95% of Albuquerque winter days. The archive's clearest example of letting physics do the control work.

Skymat: Blow-molded polypropylene solar collector/radiator panels used in Zomeworks' thermosiphon systems. Two 10-sq-ft panels heated Baer's shower through "icy January weather" in Albuquerque without glazing.

Skytherm: Harold Hay's roof-pond passive system. Water bags on a flat roof absorb heat through the day and radiate to the night sky; movable insulating panels reverse this cycle seasonally. No pumps, compressors, piping, or ducts. A 1,100 sq ft Atascadero, CA house (1973) maintained 68–72°F year-round. The conceptual ancestor of Baer's Cool Cell.

Sol-air temperature: A composite temperature measurement used as a control sensor for pool-heater cooling systems. The pump activates when it drops below a setpoint, indicating radiative conditions favor cooling.

Solar Building (Albuquerque, 1956): The Bridgers & Paxton engineering firm's office at 213 Truman St. SE, with solar collectors on a 30° south wall and a 6,000-gallon underground storage tank. Listed on the National Register of Historic Places (1989).

Solar Fools: An open-source community continuing Steve Baer's work under the "CoolSky" brand, led by Jose Baer, Bruce W. Davis, and Paul Hildebrandt. Mission: replace polluting HVAC with "elegant, affordable, and non-polluting passive systems." Website: solarfool.org.

Solar insecticide: Baer's metaphor for government solar research grants: like releasing sterile male insects, they crowd out the fertile ones.

Solar PPA (Power Purchase Agreement): The financing model from photovoltaics where a provider owns hardware and sells energy below the utility rate. Cited as the closest working analog for thermal-as-a-service.

Solar vaccination: Baer's metaphor for government solar funding as "a vaccination against the full-blown disease of solar energy utilization" — an immune response that prevents widespread adoption.

Solaris: Harry Thomason's solar heating system, demonstrated in three solar houses in Washington DC at $1–2 per sq ft. Presented at the 1961 UN Conference on New Sources of Energy.

Split incentives: The structural market barrier where the builder pays for construction while the occupant pays for energy, so cheaper-to-build wins over cheaper-to-run. TaaS resolves this by making the provider both equipment owner and performance-paid party.

Stagnation temperatures: The equilibrium temperatures reached by surfaces in still air with no applied load, as demonstrated by the IR-thermometer parking-lot exercise. "A walk through a parking lot becomes a lesson in the effect of colors and orientations."

Stock pond melter: Baer's first closed-loop thermosiphon device (c. 1967–68), using aluminium pipe and rubber hose filled with methyl alcohol to keep a hole open in frozen stock ponds. US Patent 3,618,569 (1971). Identified by Kayatekin as the seed of the entire Double Play lineage.

Sun-dwellings: NMSEA's first major project: four passive-solar dormitory test units at Ghost Ranch designed by a team headed by Peter Van Dresser (1973–76). The best unit supplied 78% of its needed heat versus 18% for the control.

Sunbender: Zomeworks' reflector/shade system for south-facing collectors and skylights. In winter, an aluminum reflector increases solar gain by over 30%; in summer, the panel pivots to shade. Uses the same refrigerant-canister physics as the Skylid. US Patents 4,275,712 (1981) through 4,505,255 (1985).

Sunmen: Baer's 2004 manifesto describing measurement-driven practitioners whose education "begins with picking up an infrared scanner." The archive's clearest articulation of his empiricist philosophy: "One can no more subsidize the sun than heat it up."

Sunspots: Collected Facts and Solar Fiction: Baer's 1975 book (Zomeworks Corporation), eleven chapters mixing solar science with interleaved fiction. The earliest dense primary source in the archive, establishing the voice, analogies, and policy stance that run through all later documents.

Tax shine: Baer's satirical term for economic distortions from solar tax credits. Unlike sunshine, tax shine "only gets bright for some by making things dark for others" and reaches only PV panels and corn, not windows or skylights.

Technological complexity trap: Bruce W. Davis's argument that Passive House standards push complexity (HRVs, airtight membranes, monitoring) that becomes obsolete within years. The simpler passive approach has no certification industry and no trade lobby. "It is too simple to sell."

Thermal time constant: The time after which 1/e (37%) of a temperature difference remains during exponential cooling or heating. Water's high specific heat gives buildings long time constants, smoothing hourly weather and tracking the diurnal cycle.

Thermal vision of night: Baer's concept (2002) that night is not thermally empty but full of radiant exchange — surfaces cool by radiating to the sky, and air is cooled only secondarily by contact. Central argument: "Air temperature is vastly over honored and over measured."

Thermal-as-a-service (TaaS): A proposed business model where a provider owns passive thermal equipment and sells comfort as a monthly fee below the building's current cooling cost. Resolves split incentives, upfront capex, and builder unfamiliarity without changing the physics. Analogous to the solar PPA.

Thermally slow buildings: Buildings with sufficient thermal mass (especially water) to smooth hourly weather and track only the diurnal cycle. Their slow response time is the source of comfort in passive thermal design.

Thermosiphon: Passive fluid circulation driven by temperature-induced density differences — warm water rises, cool water sinks — requiring no pump. The operating principle behind the Cool Cell and Double Play systems. At miniature scale (below ~80 ft³), becomes marginal due to friction losses scaling as 1/D⁴.

Three pillars (water, sky, comfort): The archive's central convergence: (1) the sky as a reliable heat sink, (2) water as the carrier and storage medium, (3) radiant comfort as the adoption lever. All three must align for passive thermal systems to succeed.

Tilt correction factor: Discovered in the NSRC report: tilting panels from horizontal to vertical reduced cooling by only ~25%, about half the loss predicted by geometric view-factor formulas, giving designers more placement flexibility.

Track Rack: Zomeworks' passive solar-panel tracker that follows the sun without electricity, using refrigerant-canister weight transfer. "The undisputed cadillac of the tracker industry." Along with Fixed Racks and Battery Boxes, the product line that funded Double Play development.

Tribal Messenger: A New Mexico newsletter in which Baer serialized a solar energy book from March through October 1973, one chapter per biweekly issue. The 46 files form the earliest extended writing in the archive, teaching solar physics through everyday objects — junkyard radiators, car crashes, rock bins.

Triple play collector system: An unglazed collector serving three functions: domestic hot water, space heating, and space cooling. From the NREL paper by Burch et al. (2003), which credited Baer with motivating the work.

Trombe wall: A masonry thermal mass wall behind glazing on a building's south face, absorbing solar heat and radiating it inward. The DrumWall is Baer's water-based alternative.

Two traditions: The archive's finding that solar energy split into an institutional tradition (Daniels, Bliss, MIT, USAF) and a counterculture tradition (Baer, Hay, Thomason). Both reached the same physics but neither adequately informed the other.

U-value (heat loss coefficient): Thermal conductance measured in the heated/unheated plates experiments: 1.6 BTU/°F·ft²·hr for vertical surfaces and 2.16 for horizontal — the horizontal surface loses heat faster due to its unobstructed sky view.

U-zero (open-ventilation concept): Baer's engineering concept (derived from 1984 measurements at his house) sizing natural ventilation openings at 1–2 CFM per sq ft of exposed thermal mass to ensure adequate night cooling.

Unglazed solar collector: A collector without a glass cover — lower cost (under $1/ft² vs. ~$15/ft² glazed), moldable to look like ordinary roofing, and capable of radiating freely to the sky at night. The tradeoff is wind and convection loss. Performance depends heavily on climate.

USAF Passive Solar Handbook: A 5-volume US Air Force guide (c. 1985) defining passive cooling as only air-based strategies (natural ventilation and night mechanical ventilation) with no mention of Hay, Baer, Skytherm, or roof ponds. Concrete evidence for why water-based passive cooling never entered institutional practice.

Validation gap: The pattern where independent parties confirm the physics, economics, and importance of passive thermal systems — yet the building industry has not adopted them. The gap is institutional, not technical.

Water circuits: The archive's deepest design principle: "Design the water circuit first; the hardware follows." The building hardware is just the plumbing connecting water to the sky, the sun, and the occupant.

Water wall: Water-filled containers behind south-facing glazing, absorbing solar heat and radiating it inward. David Bainbridge's 1981 Water Wall Solar Design Manual traces the concept to Hoyt Hottel's 1947 MIT test cubicles and credits Baer's 1971 house as the catalyzing event.

Water Innovation Fund: A New Mexico state program under Governor Richardson that financed the 2006 NSRC report.

White-plate sensor: A measurement technique credited to Baer, using a white plate's temperature as an integrated measure of radiant cooling potential instead of correlating individual weather variables.

Whole Earth Catalog: Stewart Brand's countercultural reference catalog, first published fall 1968. Its format was directly influenced by Baer's Dome Cookbook. The Fall 1969 edition sold 100,000 copies in four weeks.

Yakhchal: Ancient Persian domed ice-storage buildings (by 400 BC). Qanat-fed water froze overnight in shaded channels; ice was stored in domed structures with walls up to 2 meters thick. The same night-sky radiative cooling and water-thermal-mass physics as the archive's modern systems, deployed at civilizational scale 2,400 years earlier.

Yellott Number: A dimensionless number named for solar engineer John I. Yellott, used to characterize thermosiphon solar water heaters.

Yis-Sol pump: A solar-powered pump demonstrated by Baer at the 1968 Solar Energy Convention, exploiting liquids with different thermodynamic properties to pump water using only solar heat.

Zome: A structure derived from zonohedra — convex polyhedra whose faces are parallelograms in parallel zones. The word fuses "zone" and "dome," coined by Baer and Steve Durkee. Unlike geodesic domes, zomes can be stretched and clustered freely. US Patent 3,722,153 (1973), with geometry research dating to December 1964 in Zurich.

Zome Alloy: Oscar Tuazon's 2016 full-scale plywood artwork of interconnected rooms inspired by the Baer House. Shown at Art Basel 2016 and later at MSU Broad's Water School exhibition.

Zome Primer: Baer's 1970 publication (36 pages) formalizing the 31-zone structural system, including "The Divine Proportion" chapter on the golden ratio in icosahedral geometry.

Zomeworks Corporation: Steve Baer's passive solar engineering and manufacturing company, co-founded c. 1969–70 with Barry Hickman and Ed Heinz in Albuquerque. Institutional home for every product and patent in the archive. Following Baer's death in May 2024, the company passed to new ownership under Benjamin Rodefer.

Zomeworks patent arc (1969–2002): The 33-year sequence of 15 patents from osmotic heat pipe (1969) to Cool Cell (2002). Each cluster resolves a constraint from the previous one: geometry → movable insulation → passive tracking → battery cabinet cooling → roof containers → full building integration.

Zomeworks shipping container prototype: A 20′ × 8′ cargo container retrofitted with roof water bladders as a low-cost Double Play testbed (2025–26). Represents the retrofit-first strategy pushed to its extreme: a modular asset a TaaS provider could own, deploy, and reclaim.

Zometool: An educational ball-and-strut geometry construction kit founded by Paul Hildebrandt, built on Baer's 31-zone system. The ball has a hole for each of the 31 directions; struts come in three types. Adopted by scientists for quasicrystal demonstrations. Distinct from Zomeworks.

Zonohedron: A convex solid whose faces are polygons with edges in equal and parallel pairs, each edge belonging to a zone — a band of parallel edges encircling the solid. The number of face planes for an n-zone system is n(n−1)/2. The geometric foundation for zome structures.