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concepts · updated 2026-10-30

Zomeworks shipping container prototype

confidence: medium volatility: warm verified: 2026-11-04fresh

Zomeworks 8'×20' high-boy cargo container retrofitted with a Double Play passive heating/cooling system: 3 south-wall selective-surface absorber panels, 8 rooftop urethane water bladders with Styrofoam insulation floats, and a secondary metal radiator roof. Originally designed by David Harrison (2010–2012), commissioned circa 2012–2013. Harrison's October 2026 as-built drawing set (10 sheets), system description, and seasonal conversion procedure provide the first detailed technical documentation in the archive.

Four photographs plus a hand-drawn schematic document a Zomeworks shipping container prototype in the Albuquerque area. The first two photographs are undated (circa 2025, source unknown); two follow-up photographs of the same installation are EXIF-dated March 25, 2026 (iPhone SE 3rd generation), and the schematic is EXIF-dated July 10, 2026 (iPhone 17e). Zomeworks’ own R&D page (fetched July 2026) confirms the project: a 20’ × 8’ cargo container retrofitted as a Double Play structure, using water bladders on the roof instead of ceiling storage — “a much less costly application” — “to be tested in Albuquerque.”

What the photographs show

Interior view looking up at Double Play metal ceiling panels with hydronic piping, brass fittings, and a CFL lamp pendant

Interior Double Play ceiling panel system — dark corrugated metal panels act as both radiant ceiling and thermal mass; white hydronic pipes carry fluid between ceiling and storage. Brass compression fittings visible at pipe junctions.

Exterior of a converted shipping container building in a New Mexico desert setting, with black thermal absorber panels covering the south-facing wall

Exterior — converted shipping container with black thermal absorber panels on the south-facing wall. The absorbers (unglazed pool-style collectors) collect heat in winter and radiate to the night sky for cooling in summer. The white metal roof is the exterior face of the Double Play radiant ceiling seen above.

The images document a shipping container that has been adapted or is being prototyped as a thermal system platform. Shipping containers offer a standardized steel shell — a modular, relocatable building envelope that could serve as a testbed or product platform for passive heating and cooling systems.

Follow-up documentation (March and July 2026)

Exterior of a tan-painted shipping-container building with vertical black thermal-absorber panels between two windows, in a high-desert lot

A later, wider exterior view of the same container — same tan siding, same black absorber panel pattern, same roofline and door hardware as the original exterior photo above.

Interior view looking up at the Double Play ceiling, showing white push-fit tubing running to several brass manifold fittings across the structural beams

A closer interior view of the radiant ceiling piping — the same “ARTlines” poster visible through the doorway confirms this is the same room as the original interior photo.

Hand-drawn schematic titled "DOUBLE-PLAY CONTAINER ZOMEWORKS" showing a roof-mounted night-cooling radiator, an "Energie Solaire Collector," and a "Thermal Storage-Water" reservoir inside an insulated container, connected by color-coded supply/return piping

A hand-drawn system schematic diagramming the full loop: solar collector → thermal storage water → night-cooling radiator on the roof → back to storage → back to collector. This is the clearest single diagram in the archive of how the double-play thermosiphon‘s three stages — collection, storage, night radiation — connect as one closed loop.

Why it matters

The container prototype represents a continuation of the archive’s thermal vision into 2026. Where the original work focused on custom-built structures (the Baer Zome cluster, the Andy Shack, Bruce Davis’s studio) and the two Double Play test outbuildings at Zomeworks headquarters (one now for sale, the other used for meetings and tours), a shipping container approach would make passive thermal systems deployable in a standardized, mass-producible form factor. Zomeworks names cost as the remaining hurdle — the original building design “needs more development to bring down costs,” and the cargo-container iteration is the low-cost path being pursued. The R&D page also states the system’s climate limits plainly: “Double Play systems work best in dramatic climates such as the West and Southwest of the United States, where nights are cool, days are hot and winters are sunny.”

Note a design-detail disagreement between the sources: the R&D page describes the container variant as using water bladders on the roof in place of ceiling storage, while the July 2026 hand-drawn schematic shows a “Thermal Storage-Water” reservoir inside the insulated container, fed by an Energie Solaire collector and a roof night-cooling radiator. These may be successive iterations of the same low-cost storage question; the archive does not yet settle which configuration was built.

Current use and system details (Oct 2026 meeting)

Bruce Davis and the Solar Fools team (Oct 14, 2026 meeting) clarified the container’s purpose and configuration:

  • Primary use: Baer family storage — not designed for human occupancy
  • Thermal configuration: water on top, using polyurethane bags with styrofoam rafts as the thermal storage medium; the bags are drained in winter
  • Collectors: Energy Solaire collectors; no louvers
  • Performance envelope: maintains a temperature range of approximately 40°F to 90°F — more of a Cool Cell than a habitable space
  • Open question: why was the container built? The meeting raised whether it was intended to test an entirely new system configuration

This confirms the container is closer to the Cool Cell lineage (climate-controlled storage) than to the habitable Double Play buildings (Andy Shack, Davis Studio, Sol-Mod). The polyurethane-bag-with-styrofoam-raft approach to roof water storage is a distinct variant not documented elsewhere in the archive.

Detailed technical documentation (Harrison, Oct 2026)

In October 2026, David Harrison revisited the Double Play Container, took notes, and recovered the original design drawings from an old thumb drive. He reworked the drawings to reflect the as-built condition and shared them with the Solar Fools group via Bruce Davis. This is the first detailed engineering documentation of the container in the archive.

System description

The container is a modified 8’ × 20’ “high boy” cargo container with an insulated and finished interior. The Double Play system has three components:

  1. Solar absorbers: 3 south wall-mounted, unglazed stainless steel selective-surface hydronic panels (34” × 93” each), plumbed to the rooftop bladder system via Wirsbo PEX lines
  2. Thermal storage: 8 custom 20-mil urethane water bladders (24” × 12’ × 86”), each with a 4½” Styrofoam insulation float, in direct contact with the steel ceiling of the container
  3. Radiator: A secondary 14-gauge painted metal roof installed above the bladder and framing, which radiates heat to the night sky for cooling

The roof structure consists of 9 double 2×12 #2 Hem Fir rafters at 27” on center, mounted on ⅛” × 4” × 2½” steel plates welded to the container’s top edges. Three 1½” square steel tubes run the length of the shelter, lagged through the metal container ceiling into the rafter system, supporting the bladder weight. Wall insulation is 4” polyisocyanurate; the floor has sprayed polyurethane foam; interior finish is ½” melamine composite wall panels on wood purlins.

Operational modes

The system operates in four seasonal modes, controlled by manual valve changes:

  • Heating mode: Absorber panels full, bladder ceiling valves open, northwest water-level adjustment valve opened to set bladder level below the float. Solar-heated water thermosiphons from the absorbers up into the bladders.
  • Cooling mode: Bladders filled to maximum (via ullage overflow), bladder-to-absorber valves closed, absorber panels drained. The full bladders absorb interior heat by day; the roof radiates it to the night sky.
  • Coasting mode: All bladder valves closed, absorbers drained, bladder water level dropped below the float. The thermal mass of the residual water provides passive temperature moderation.
  • Freeze protection: Bladder water level drained below the float to prevent plumbing freeze damage.

Off-grid electrical system

The container has a standalone 24V photovoltaic system: 4× Hoxan 55W modules (220W total) on a Zomeworks tracker, Morningstar Prostar 15 charge controller, 2× Morco 105Ah 12VDC batteries, and an Exel Tech 600W inverter. The system is labeled “Holly’s Container Watt Box” on the drawing, suggesting it was commissioned for Holly Baer.

Design timeline

Harrison’s drawings span 2010–2012 (original design) with sheets 3–7 updated in October 2026. Harrison dates construction and first commissioning to approximately 2012–2013. After the container left the Zomeworks yard, Harrison “had little to no further involvement.” His 2026 commentary notes that cooling should be “pretty easy in Santa Fe” but heating may be difficult without glazing over the absorbers — wind and cold drag heat away — and that adjustable shading would help prevent overheating in warm sunny weather.

Design-detail resolution

The earlier disagreement noted in this article — between the Zomeworks R&D page (water bladders on the roof) and the July 2026 hand-drawn schematic (thermal storage water inside the container) — is now resolved by Harrison’s documentation. The system uses both: urethane bladders sit atop the container in direct contact with the steel ceiling (roof storage per Zomeworks), but the bladders condition the space below through the ceiling contact (interior storage effect per the schematic). The Styrofoam float insulates the water from the radiator roof above when cooling is not desired.

Absorber panel construction

Harrison’s tune-up document provides the first detailed description of the absorber panels. They are stainless steel sheets with a dimpled regular pattern, seam- and spot-welded together in an offset configuration that creates a free-flowing waterway wetting the entire surface. The panels are freeze-tolerant by design: the envelope “pooches about 9%” when frozen but does not deform permanently because it operates under low pressure — unlike rigid pipe, which gulps and distorts with each freeze cycle. No antifreeze is needed. The selective-surface coating on the front face is fragile; repairs require care to avoid damaging it (a damp cloth keeps the surface cool during silver-soldering on the back). Panel dimensions are 93” × 30.75” per the drawing set.

Maintenance status and recommendations (Harrison, Oct 2026)

Harrison inspected the container and compiled a tune-up requirements document identifying several items needing attention before or after relocation:

Immediate repairs:

  • The west solar absorber has a leak on the bottom back side, likely at a male barb fitting. Repair requires removing the interior wall panel, isolating the absorber by closing bladder valves, cutting the PEX, and silver-soldering the fitting with refrigeration-grade solder. Replace plumbing with ½” Uponor type “A” pipe and expansion collars. Potable water is required for filling.
  • Roof water run-off has stained two absorber panels. Flashing should be installed above the panels to deflect run-off.

Structural safety concern: The ceiling is held up by 3 square steel tubes lagged through the metal container ceiling into the rafter system with 5/16” × 6” lag screws (approximately 3” penetration into the rafter). Harrison notes the lags were installed with caulk, which would mask any leak above the ceiling — water could cause mold, rot, and eventual failure. He recommends:

  1. A registered engineer should review and approve the lag connection detail
  2. Replace existing lags with 3/8” × 8” lags for deeper penetration
  3. Drill weep holes on the centerline of the doubled rafters (no holes between rafters — that would puncture a bladder)

System improvements:

  • Replace the roof ullage drain plug with a valve extended down for convenient access
  • Add a dedicated fill fitting: extend the south high-side header to a frost-proof garden hose bib (without a backflow preventer — water must flow both directions)
  • Install “Non Potable Water — Do Not Drink” signage on all exterior plumbing

Bladder inventory: 8 bladders installed; 12 were purchased originally. The 4 spares (in a cardboard box) are believed to be at the Baer house and should travel with the shelter.

Water load: Total water head pressure above the ceiling is approximately 14”. The 4½” Styrofoam float displaces some volume and weight within the 11” bladder cavity.

Off-grid power: The Wattbox was working when the container was in the Zomeworks yard. Best case: only a battery replacement is needed. The Tank Top Cool Cell battery enclosure was still holding water and should be topped off when serviced.

See also

Sources