Mechanism
The cavity manifold operates as a passive-active hybrid heat exchanger embedded within the structural element of a building. The structural element, typically a poured concrete wall, floor slab, or foundation block, provides a large thermal mass with a heat capacity on the order of 0.9 kJ/(kg·K) and a density of 2,400 kg/m³, giving a per-cubic-meter heat capacity exceeding 2 MJ/K. The manifold is a network of channels cast into this mass during the pour, geometrically configured to admit fluid or air flow along surfaces that contact, surround, or pass beneath the carbon-bound cell housing.
Heat transfer between the cell and the structural mass proceeds through three coupled modes. The first is conduction across the cell housing into the channel walls, governed by the housing material's conductivity and the thermal contact area. The second is forced or natural convection within the channel, driven either by an HVAC-coupled circulation loop or by buoyancy-induced flow during off-cycle periods. The third is conduction from the channel walls into the bulk of the structural element, governed by the structural material's conductivity (approximately 1.7 W/(m·K) for typical concrete) and the channel-density-weighted surface area. The manifold geometry, channel cross-section, channel-to-channel spacing, and channel routing topology, is engineered to balance these three modes against the cell's expected cycling profile and the building's HVAC schedule.
The transient response of the coupled system is dominated by the structural element's Biot number and Fourier number computed against the channel-spacing length scale. For typical residential basement-wall geometries with channel spacings of 100 to 200 mm, the Fourier characteristic time is on the order of one to four hours, giving the structural mass a smoothing role that decouples short-duration cell cycling events from slow building-envelope heat exchange. This separation of timescales is exploited by the cell controller, which treats the manifold attestation's bulk capacity as a near-infinite reservoir for excursions shorter than the Fourier time and as a constrained shared resource for sustained operations spanning multiple Fourier intervals. The manifold geometry is engineered to place the desired Fourier time at the boundary between expected short-cycle and sustained-load regimes.
Operating Parameters
Channel cross-section is typically 10 to 50 mm in hydraulic diameter, sized to admit the volumetric flow required to extract peak cycling heat without inducing pressure drops that exceed circulation-pump capacity. Channel density, measured as channel cross-section per unit structural-element cross-section, is typically 1 to 10 percent, sufficient to provide the thermal coupling required without compromising the structural element's load-bearing capacity. Channel routing is engineered case by case to align with the structural element's reinforcement layout and to maximize contact area between the manifold and the cell housing.
In heat-extraction mode the manifold removes heat at rates up to 100 W per cell during high-current cycling, sustaining cell temperatures within the operating envelope (-40 to +80 °C for polymer-membrane embodiments) even when discharge current densities approach the 1,000 mA/cm² peak. The extracted heat is deposited into the structural mass, where it diffuses on a timescale of hours to days and is ultimately rejected to ambient through the building envelope, into HVAC return air, or, in heat-pump-coupled embodiments, into domestic hot water or space heating loads.
In heat-retention mode the manifold reverses the coupling: ambient or HVAC-supplied heat is delivered to the cell through the same channel network, maintaining cell temperature above the lower envelope bound during cold-weather operation. This mode is particularly important for polymer-membrane embodiments, where electrolyte freezing or membrane dehydration at low temperature would otherwise prohibit discharge. The transition between extraction and retention is managed by the building HVAC controller in coordination with the cell controller, with both states represented as signed regions on the manifold's thermal admissibility surface.
Alternative Embodiments
A residential embodiment integrates the manifold into a poured basement wall or slab, with channels routed in a serpentine pattern that maximizes contact length with the cell housing. The channels couple to a hydronic loop already present for radiant floor heating, admitting bidirectional thermal exchange without dedicated infrastructure. A commercial-scale embodiment integrates the manifold into a structural-core wall serving multiple cell modules, with channels arranged in parallel banks that admit independent thermal control of each module while sharing the building thermal mass.
A retrofit embodiment substitutes a surface-mounted manifold cast against an existing structural element, recovering most of the thermal-coupling benefit at the cost of reduced structural integration and slightly higher contact resistance. A high-temperature ceramic-membrane embodiment uses a manifold cast in refractory concrete with channels routed for forced-air cooling, admitting cell operation up to 600 °C while protecting the surrounding building structure with an intervening insulation layer.
A foundation-slab embodiment routes the manifold beneath a slab-on-grade foundation, exploiting the deep ground-thermal mass adjacent to the slab as an extended sink. The channel network is bifurcated: a near-cell loop transports peak-cycling heat to the foundation slab, while a far-loop couples the slab to the surrounding earth through a configurable thermal valve. The valve admits the foundation slab to act either as an insulated buffer or as a coupled ground-source exchanger depending on season, occupancy, and grid-services contract, with the manifold attestation declaring which mode is currently active. A modular prefabricated embodiment integrates the manifold into precast concrete panels at the factory rather than during on-site pour, with the channels formed against tooling that produces a consistent hydraulic-diameter and surface-finish profile across panels; site assembly then consists of joining manifold-bearing panels with credentialed coupling collars that themselves attest the joint's thermal continuity.
Composition
The cavity manifold exposes a thermal-coupling surface attestation signed under the building's credentialed admissibility profile. The attestation declares the manifold's heat-extraction capacity, heat-retention capacity, channel topology, and structural-mass coupling parameters as a callable predicate that upstream systems may query. The cell controller queries the attestation before admitting high-current cycling; HVAC dispatch agents query the attestation when scheduling thermal loads against the structural mass; building energy management systems query the attestation when computing aggregate thermal capacity for grid-services contracts.
Composition with the cell operating envelope is symmetric: the cell envelope expands when the manifold attestation admits higher heat-extraction rates, and the manifold's effective capacity increases when the cell envelope narrows below the manifold's design point. The composed envelope is a credentialed conjunction, recomputed whenever either constituent attestation is refined and made available as a single composite predicate to higher-level composers.
Prior-Art Distinction
Conventional building-integrated thermal storage uses dedicated water tanks, phase-change materials in discrete enclosures, or active radiant systems with circulation loops separate from the building structure. The cavity manifold differs in placing the heat-exchange channels directly within the load-bearing structural element, eliminating the dedicated enclosure and exploiting the building thermal mass that would otherwise be inert. Conventional battery thermal management uses cooling plates, jackets, or immersion baths external to the cell and to the building; the cavity manifold collapses both functions into a single structural-and-thermal artifact.
The credentialed thermal-coupling surface attestation distinguishes the manifold from passive thermal-mass structures (such as Trombe walls and rammed-earth construction) that provide thermal capacity but expose no callable composition interface. The combination, structural integration, bidirectional cell coupling, and credentialed composition, is not present in prior building-integrated battery or thermal-storage architectures.
Hydronic radiant-floor systems and slab-embedded heating-cooling tubing share the mechanical motif of channels in concrete but differ in purpose and interface: such systems serve room-comfort conditioning through a single thermal direction at a time, with control vested in a thermostat-driven actuator and no provision for callable attestation by upstream electrochemical or grid-services agents. Geothermal heat-exchanger boreholes likewise share the heat-pump-coupling motif but couple to the deep-ground reservoir rather than to the building's load-bearing structural mass, and again expose no per-cell credentialed coupling surface. The disclosed manifold combines the structural-mass thermal reservoir of the latter with the close-cell thermal proximity of dedicated battery cooling and adds the credentialed attestation that neither prior class admits.
Disclosure Scope
The cavity manifold thermal-coupling primitive disclosed in Provisional 64/050,895 covers channel networks formed within structural elements during pour through manifold-defining sacrificial formwork, configured to thermally couple electrochemical cells to the building thermal mass, exposing a credentialed thermal-coupling surface attestation. The disclosure spans residential, commercial, retrofit, and high-temperature embodiments and does not constrain the channel-network topology beyond the requirement that geometry be engineered to balance heat-extraction and heat-retention rates against the cell's operating envelope and the building's HVAC schedule.
The disclosure further covers methods of attestation refinement, updating the thermal-coupling surface in response to measured channel-flow performance, structural-mass thermal-conductivity drift, and accumulated cycle history, and methods of composition with upstream admissibility profiles for cell controllers, HVAC dispatch agents, and building energy management systems.
The disclosure additionally covers manifold-defining sacrificial formwork techniques: water-soluble polymer cores, low-melting-point waxes, and inflatable bladders that occupy the channel volume during the structural pour and are subsequently removed by dissolution, melting, or deflation. Each formwork variant produces a different channel-wall surface character, smooth or textured, planar or contoured, and the disclosure spans selection of formwork variant against expected flow regime and channel-wall heat-transfer requirements. The formwork itself is treated as a manufacturing artifact whose specifications are recorded against the resulting structural element's credentialed thermal-coupling surface attestation, providing traceability from as-built channel geometry through to operational thermal-admissibility bounds.
Finally, the disclosure covers integration patterns in which a single structural element hosts manifolds for multiple electrochemical cells arranged in a coordinated thermal-management group. The shared structural mass admits load-balancing across cells, heat extracted from a high-current cell may be deposited near a cold cell requiring heat-retention, with the structural mass acting as a buffer that decouples the cells in time while coupling them in aggregate thermal capacity. The credentialed surface attestation is correspondingly extended to declare per-cell coupling parameters and inter-cell coupling coefficients, admitting precise composition with multi-cell controllers.
The disclosure also spans methods of as-built verification: post-pour thermal-imaging surveys, channel-flow pressure-drop measurements, and structural-mass conductivity probes that calibrate the as-cast manifold against its design specification and produce the initial signed thermal-coupling surface attestation. Subsequent in-service refinement of the attestation tracks slow changes in concrete moisture content, channel fouling, and structural-mass cracking, producing a service-life trajectory that informs both cell-controller dispatch and building maintenance scheduling. These methods together establish the manifold not as a static infrastructure component but as a credentialed, evolving, composable artifact whose thermal performance is continuously available to upstream systems as a signed predicate.
