Night interior of a faceted vault: a low hinoki kotatsu table, a stone-clad radiant hearth on its own plinth and a heated sleeping platform, snow and mountains beyond the shoji gable

環M06 + M08 Systems · Loop

Nothing leaves.
Heat the human,
not the air.

Five streams leave the house and come back as showers, fertiliser, larvae and greens. One 48–60 V DC spine runs every organ, banks spare sunshine as hot water, and warms the people at the kotatsu before it warms the room.

Follow the five streams Run a day on the spine

5 streams separated at the source48–60 V DC spine, no inverter stages2.5–3 kWh of heat per PV kWh calculated98 % ISS water recovery measured

I12 · Irori hearth interior · concept visual · AI

環01 MOTTAINAI loop · M06

Five streams in. Water, nitrogen and food back out.

Mottainai means “what a waste”. Each drain is kept separate at the source, so each one can come back as an input or leave as a regulated export. Click any organ to see how it works and the numbers behind it. Change the household and the flows follow.

Fig. 01 · Daily mass flows · 4 people

Band width is set per stream. Splits inside a stream are to scale. Particles show the direction of flow.Click an organ · hover a band · swipe sideways

People 4

Water demand 80 L/person/day

MIZU net recovery 92 %

HATA cassettes 1

Water back to the taps

294L/day

New water needed: 26 L/day calculated

Urine nitrogen

12.8kg N/yr

The farm takes 2–4 %. The rest goes to beds or offtake.

Zeolite exchange used

1.8–3.5kg/day

Regenerated weekly in place with a KCl/NaCl rinse calculated

Scraps → larvae

0.15–0.50kg/day

From 1–2 kg/day of residue target

Loop electricity

12–16kWh/day

MIZU ≤ 9.6 + condensing 2.7–6.3 calculated

SEPARATE at the source: urine-diverting dry toilet (no blackwater), grey drains (kitchen sink via a grease interceptor), kitchen organics bin, crop residue chute, HRV/dehumidifier condensate line.
GREY: the MIZU organ runs biology, membrane, RO, UV and chlorine; up to 97% is reused with rainwater make-up (vendor spec); make-up water is logged separately; RO reject goes to solar membrane distillation, ornamental irrigation or the holding tank.
YELLOW: urine is stabilised by storage or acidification so ammonium (NH4+) stays the dominant species, then passes a clinoptilolite exchange bed that captures NH4+ and K+ at 10-20 mg N/g. The bed is regenerated in place with a KCl or NaCl rinse, which produces a liquid NH4/K fertiliser; it is not a disposable pod. (Alternative: full nitrification to nitrate liquor used directly as hydroponic feed, the Aurin/VUNA route.)
Charged zeolite also feeds zeoponic seedling trays and substrate beds in HATA; surplus nitrogen goes to outdoor beds or to a fertiliser offtake, because one NFT rack uses only a few percent of household urine N.
BROWN: dried faeces from the ventilated chamber are composted thermophilically for non-food landscape, or incinerated or collected where regulation requires.
GREEN: kitchen and crop residue (about 1-2 kg/day for 4 people) feed a BSF larvae bin on a 10-14 day cycle; larvae feed fish or poultry, frass goes to outdoor beds.
AIR-MOISTURE: plant transpiration and breath are condensed by the dehumidifier and HRV and returned to the grey intake.
LUNG: sealed farm modules carry a bladder that absorbs pressure swings and receive the living unit's CO2-rich exhaust through a HEPA and activated-carbon stage, within a stated humidity budget (target about 1,000 ppm CO2 in the grow zone).
SODIUM: recirculating nutrient is bled off on a sodium set point to the holding tank (urine carries about 2-4 g Na per person per day).
MONITOR: EC, pH, ORP, turbidity and Na online; quarterly lab panels for pathogens and pharmaceuticals; anything out of spec goes to the sanitary holding tank or septic connection.

水02 How the loop closes

Ten rules, and a fallback that always works.

The loop is built from parts that already run somewhere: WOTA’s grey-water units, ISS condensate recovery, NASA zeoponics and household larvae bins. The new part is how they are joined. Anything out of spec goes to the sanitary holding tank, so the loop fails safe.

01Separate at the source
Urine-diverting dry toilet (no blackwater), grey drains (kitchen sink via a grease interceptor), kitchen organics bin, crop residue chute, HRV/dehumidifier condensate line.
02Grey
The MIZU organ runs biology, membrane, RO, UV and chlorine; up to 97% is reused with rainwater make-up (vendor spec); make-up water is logged separately; RO reject goes to solar membrane distillation, ornamental irrigation or the holding tank.
03Yellow
Urine is stabilised by storage or acidification so ammonium (NH4+) stays the dominant species, then passes a clinoptilolite exchange bed that captures NH4+ and K+ at 10-20 mg N/g. The bed is regenerated in place with a KCl or NaCl rinse, which produces a liquid NH4/K fertiliser; it is not a disposable pod. (Alternative: full nitrification to nitrate liquor used directly as hydroponic feed, the Aurin/VUNA route.)
04Charged zeolite
Also feeds zeoponic seedling trays and substrate beds in HATA; surplus nitrogen goes to outdoor beds or to a fertiliser offtake, because one NFT rack uses only a few percent of household urine N.
05Brown
Dried faeces from the ventilated chamber are composted thermophilically for non-food landscape, or incinerated or collected where regulation requires.
06Green
Kitchen and crop residue (about 1-2 kg/day for 4 people) feed a BSF larvae bin on a 10-14 day cycle; larvae feed fish or poultry, frass goes to outdoor beds.
07Air-moisture
Plant transpiration and breath are condensed by the dehumidifier and HRV and returned to the grey intake.
08Lung
Sealed farm modules carry a bladder that absorbs pressure swings and receive the living unit's CO2-rich exhaust through a HEPA and activated-carbon stage, within a stated humidity budget (target about 1,000 ppm CO2 in the grow zone).
09Sodium
Recirculating nutrient is bled off on a sodium set point to the holding tank (urine carries about 2-4 g Na per person per day).
10Monitor
EC, pH, ORP, turbidity and Na online; quarterly lab panels for pathogens and pharmaceuticals; anything out of spec goes to the sanitary holding tank or septic connection.

Nitrogen, 4 people

12.8vs0.25–0.5

kg N a year in urine, against what one NFT lettuce rack takes up. Urine is a fertiliser surplus, not a farm input you can use up indoors. calculated

Every number behind the loop

M06 key numbers · 15

Number	Value	Basis
ISS water recovery with Brine Processorsource	98 %	measured
Lunar Palace 365 material closure (abstract not independently retrieved)source	98.2 %	reported
Lunar Palace urine recovery (abstract not independently retrieved)source	99.7 %	reported
Lunar Palace solid-waste recovery (the hard part; abstract not independently retrieved)source	67 %	reported
Urine nitrification energy (alternative route only)source	about 13 W per person primary (about 0.5 kWh/day electric for 4 people) W per capita	measured
WOTA Unit electric draw400 W x 24 h; vendor rating https://wota.co.jp/en/wota-unit/	400 W rated (more with heater), up to 9.6 kWh/day	calculated
Dehumidifier condensate energyresidential units give 1.5-3 L/kWh	about 0.3-0.7 kWh/L	calculated
Nitrogen in urinesource	8.8 g N/person/day	measured
Zeolite exchange capacity needed for 4 people4 x 8.8 g N / 10-20 mg N per g zeolite	about 1.8-3.5 kg/day	calculated
Urine N excreted vs one NFT lettuce rack uptake (4 people)4 x 8.8 g x 365; rack uptake at about 2.5 g N per kg fresh weight	about 12.8 vs 0.25-0.5 kg N/yr	calculated
BSF pilot (FCR 1.7-3.6 on dry matter, so not a wet-to-wet figure)source	190 kg food waste to 79 kg larvae kg	measured
BSF wet-basis bioconversion used for sizinghousehold-scale literature range; to be measured	15-25 %	target
Biosphere 2 leak ratesource	< 10 %/yr	measured
Share of excreted urine N recovered into crops or exported productsAnyground	20-50 %	target
Nitrogen mass-balance closureAnyground	within +/-10 %	target

力03 IRORI spine · M08

One DC spine. Two chemistries. Heat stored as water.

This is the service end of a home, cut open. LFP cycles every day inside the heated envelope. A small sodium-ion bank in the cold vestibule keeps comms alive if the heating fails. Spare sunshine runs a CO₂ heat pump into a 500 L tank. The optional sand hearth and the kotatsu put heat where people sit.

Fig. 03 · M08 IRORI spineNoon · bank the sun

DC bus55.2 V

LFP—

Tank top—

Hearth core—

DC powerHeatWater loopData

Drag to orbit · click a part · click, then scroll to zoom

All parts of the spine · —

力04 A day on the spine

Pick a typology and a place. Watch 24 hours balance, or not.

This runs the same model as the cutaway in 15-minute steps until the battery repeats day after day. Loads come from each module’s average power in the concept. When the sun is short, the firmware ladder sheds loads from the bottom up. A winter deficit at high latitude is planned for, not hidden.

Typology

Environment

Season

LFP per cabinet

Extra BYOBU-PV fences 0

Heat to people — kWh heat/day

Heat the human (kotatsu, −2–3 K) IRORI sand hearth Micro-hydro 300 W Backup generator

Fig. 04 · Power on the DC bus, kW

Default case without JavaScript: TABI-NO-YADO hotel, mountain site, equinox. PV 68 kWh/day against 59 kWh/day of loads; heat pump banks 36 kWh of heat.

PV + other generation

—kWh/day

—

Loads served

—%

—

Heat banked by the heat pump

—kWh_th

—

LFP state of charge

—% min–max

—

Firmware priority ladder · shed from the bottom

1Life safetyCO/CO₂, smoke, comms, HRV, DC hub—
2Water treatmentMIZU, KUMO, KAWAYA, mast pump—
3FoodCold store, farm cassettes, larvae bin—
4Heat to peopleHeat pump when the tank is empty—
5ComfortRoom lighting, robot, deck—
6Guest extrasPods and guest circuits—

—

Planning assumptions behind this chart · not from the sweeps

Sun hours, day length and heat demand vary by site and are not in the research sweeps. These planning values are stated here so you can check them. Replace them with a PVGIS run and a heat-loss calculation per site. Hot water is 1.5 kWh_th per person per day. The heat-pump compressor input is limited to 2 kW, the hearth element to 3 kW. LFP runs between a 10 % floor and a 90 % soft cap before the surplus goes to heat. Tank standby loss is ignored. The anchors from the sources are: 0.2–0.6 kWh/kWp/day in December at about 60° N reported; polar night PV near zero; COP about 3, and 1.55–1.85 at −30 °C reported; and lunar fission at 1–10 kWe speculative.

Environment	PV yield, kWh/kWp/day sum · equ · win	Daylight, h	Space heat, kWh/m²/day
E1 · Rooftop	5 · 3.5 · 1.5	15 · 12 · 9.5	0 · 0.08 · 0.25
E2 · Forest	4 · 2.5 · 0.6	17 · 12 · 7	0 · 0.12 · 0.4
E3 · Desert	7 · 6 · 4.5	14 · 12 · 10.5	0 · 0.03 · 0.1
E4 · Arctic / polar	4 · 2 · 0	24 · 12 · 0	0.05 · 0.3 · 0.6
E5 · Mountain	5.5 · 4 · 2	15 · 12 · 9	0.02 · 0.18 · 0.45
E6 · Coast / floating	5.5 · 4 · 2.2	14.5 · 12 · 9.5	0 · 0.06 · 0.2
E7 · Steppe / farmland	5.5 · 3.8 · 1.2	16 · 12 · 8.5	0 · 0.12 · 0.45
E8 · Lunar	fission 10 kWe	lunar night	0.1 · 0.1 · 0.1

守05 Heat the human

Size heat for people, not air. Then store it the cheap way.

A kotatsu, a heated sleeping platform and a good HRV let the room sit 2–3 K cooler with the same comfort. The heat pump gets 2.5–3 kWh of heat from each PV kWh. A hot rock gets one. So the tank is the default store, and the hearth is sold for comfort, not for storage.

Default store

Heat-pump water tank

Stores: ≈ 23 kWh_th calculated
From PV: ≈ 8 kWh at COP ≈ 3
Heat per PV kWh: 2.5–3 calculated
Volume: 300–500 L, 40 K swing

Comfort option

IRORI sand hearth

Stores: ≈ 25 kWh_th · 0.5 t, 230 K calculated
Standby loss: ≈ 145 W, about 14 %/day calculated
Heat per PV kWh: ≤ 1.0 resistive
Core: ≤ 250 °C, 150 mm microporous + rockwool

Rejected

1.5 t core at 400 K

Stores: ≈ 133 kWh_th calculated
Loses: ≈ 29 kWh/day, about 20 %/day
Why not: Leaks a fifth a day. Floor loading and fire risk.
Large scale: Pornainen 100 MWh: 90 % round trip measured. It does not scale down.

38–75 %

heating energy saved in offices when footwarmers let the setpoint drop from 21.1 to 18.9 °C at equal comfort. modelled

10–30 %

residential saving from a 2–3 K setpoint drop, at about 5–10 % per K. calculated

≈ 27 %

heating saved by an ERV in Arctic locations. measured

2.3 kWh

keeps Starlink and sensors alive for 72 h. The 2–5 kWh sodium-ion bank in the cold locker carries it. calculated

The spine, step by step

01Envelope first
The configurator picks panel class, kotatsu table, heated sleeping platform and HRV before any PV is sized, and plans a winter deficit at high latitude rather than a surplus.
02Generate
MIURA wings over the engawa (about 4.5 kWp after facet, hinge and frame packing losses) and BYOBU vertical bifacial fences (snow-shedding, albedo gain); micro-hydro or small HAWT only as measured-site bonuses.
03Distribute
MPPTs feed a 48-60 V bus running in the floor cassettes to JO-PORT DC islands; point-of-load converters replace inverter stages; heavy loads stay within the house DC budget or move to 380 V DC or AC.
04Store electricity
LFP inside the heated envelope for daily cycling; a 2-5 kWh sodium-ion bank in the unheated vestibule carries keep-alive loads (comms, sensors) down to its rated discharge floor so a heat-loss event never bricks the system.
05Store heat (default)
Surplus PV runs a CO2 heat pump into a 300-500 L insulated water tank, about 23 kWh thermal from about 8 kWh of PV at COP about 3.
06Store heat (optional hearth)
A 0.4-0.6 t sand or soapstone radiant hearth, core at or below 250 C, with 150 mm microporous insulation and a rockwool jacket, about 25 kWh thermal, a 12-24 h buffer. It stands on a dedicated pier or slab pad rated at least 10 kPa, off the floor cassettes; touchable faces stay at or below 45 C (ISO 13732-1); a summer vent or bypass dumps heat outside; fire separation as for a stove.
07Heat and cool
CO2 heat pump makes 70 C water; HRV with frost pre-heat; radiative-cooled roofs, windcatcher and night-sky radiator cool hot sites.
08Prioritise
Firmware ladder - life safety (CO/CO2, smoke, comms) > water treatment > food (cold store, farm) > heat to people > comfort > guest extras - with forecast-driven load shifting.
09Operate
Venus OS + Home Assistant run locally; MQTT telemetry over Starlink feeds the fleet dashboard; the site runs without the cloud.

M08 key numbers · 18

Number	Value	Basis
Stationary storage pack price (BNEF 2025)source	70 USD/kWh	measured
Installed 48 V LFP system with charger and BMS (used for budgets)market range; replaces the pack price in all budgets	about 200-400 USD/kWh	reported
Bluetti Pioneer Na (900 Wh portable): charges at / discharges at / capacity at -20 Csource	>= -15 C / >= -25 C / about 80% C / %	claimed
Sand specific capacity (dry quartz sand, cp about 0.80 kJ/kgK; soapstone about 0.27)0.80 kJ/kgK x 1,000 kg / 3,600	0.22 kWh/K per tonne	calculated
Optional IRORI hearth thermal capacity (0.5 t, 230 K swing)0.5 x 0.222 x 230	about 25 kWh thermal	calculated
Hearth standby loss at full chargeQ = U x A x dT, U = 1/(0.15/0.025 + 0.05/0.04) = 0.14 W/m2K, A about 4.5 m2 mean insulation area, dT 230 K	about 145 W (about 14%/day) W	calculated
Rejected 1.5 t core at 400 K: capacity / loss with 200 mm rockwool1.5 x 0.222 x 400; U about 0.4 W/m2K x 8 m2 x 380 K	about 133 / about 29 kWh/day (about 20%/day) kWh	calculated
Heat-pump water tank store0.5 m3 x 1.16 kWh/m3K x 40 K; COP about 3	about 23 kWh thermal from about 8 kWh PV kWh	calculated
Heat delivered per PV kWh: resistive vs CO2 heat pumpCOP of the heat pump already in the BOM, lower at -25 C	1.0 vs 2.5-3 kWh_th/kWh_e	calculated
Pornainen sand battery round-trip (heat-to-heat, 100 MWh, about 2,300 m3; does not scale down)source	90 %	measured
Footwarmers in offices: setpoint 21.1 to 18.9 C at equal comfort (simulated savings)source	38-75 % heating energy saved	modelled
Residential heating saving from a 2-3 K setpoint dropabout 5-10% per K	10-30 %	calculated
ERV heating saving in Arctic locationssource	about 27 %	measured
Basic off-grid household load vs with air conditioningsource	2,116 vs 11,822 kWh/yr	measured
Starlink Mini continuoussource	400-450 Wh/day	measured
MIURA-W peak power26.5 m2 x 0.85 active area x 0.20 x 1 kW/m2 (STC assumption)	about 4.5 kWp	calculated
Winter PV yield at about 60 N in DecemberPVGIS order of magnitude; winter plan assumes a deficit	about 0.2-0.6 kWh/kWp/day	reported
72 h keep-alive energy (Starlink about 0.45 + sensors about 0.3 kWh/day)0.75 kWh/day x 3	about 2.3 kWh	calculated

証06 How we prove it

Two 12-month rigs, each with a stated way to fail.

The grey loop and the batteries are bought, not invented. The new risks are urine-to-food, sodium-ion in the cold and a hot mass indoors. Each one has a pass gate and a kill rule written before the build starts.

環

M06 12-month prototype

MOTTAINAI loop

BOMUSD 15,000-40,000

Build: Household-scale loop: commercial urine-diverting toilet, urine storage/acidification tank, regenerated zeolite exchange columns, NFT lettuce rack plus zeoponic seedling trays and a substrate bed, BSF bin, greywater recycler (WOTA BOX rental where available), filtered CO2 transfer line, sanitary holding tank.
Test: 12 months nitrogen and water mass balance; edible-tissue pathogen and pharmaceutical tests; zeoponic trays and NFT vs Hoagland control for 3 cycles; sodium trend and bleed volume; odour and user-acceptance logs.
Pass: No pathogen exceedance in edible tissue; grey reuse >= 90% measured with make-up water logged separately; 20-50% of excreted urine N recovered into crops or exports with N balance closed within +/-10%; yield >= 85% of control.
Kill: Urine-derived fertiliser fails food-safety tests: route it to ornamentals, landscape and fertiliser offtake, keep the grey loop and BSF. Regulator refusal is a jurisdictional risk (Aurin is approved for edible crops in Switzerland), not a global kill.

PILOT grey loop (WOTA Unit pre-mass-production; WOTA BOX commercial for showers)EXPERIMENTAL urine-to-zeolite and closed nitrogen loop

力

M08 12-month prototype

IRORI spine

BOMUSD 20,000-45,000

Build: Test hut in a cold climate with DC spine, LFP + Na-ion zoning, kotatsu table and heated platform, and an A/B of a 0.5 t radiant hearth against a heat-pump water tank.
Test: One winter: hearth uncontrolled release vs prediction at 20 C ambient; useful heat per PV kWh for hearth vs tank; A/B nights at conventional vs lowered setpoint with comfort votes; 72 h keep-alive drill at -20 C with heating off.
Pass: Hearth uncontrolled release within 20% of the calculated value (about 14%/day) and touch faces <= 45 C; >= 15% heating energy reduction at equal comfort votes; comms and sensors alive 72 h at -20 C on a 2-5 kWh Na-ion bank alone, and the bank reaches >= 80% charge after warming to -15 C.
Kill: Hearth loss > 20%/day or useful heat per PV kWh below the tank's: drop the hearth as an energy store and sell it only as a comfort option; the heat-pump tank stays the default.

COMMERCIAL components (LFP, Victron, CO2 heat pumps, tanks)EXPERIMENTAL Na-ion stationary integration and the small radiant hearth

Risks we carry

M06Regulatory acceptance of urine-derived fertiliser varies by jurisdiction
M06Pharmaceutical residues
M06Sodium and salt build-up in recirculating nutrient
M06Nitrogen surplus with no local outlet
M06Humidity, VOC and bioaerosol transfer from living unit to farm
M06BSF economics failed industry-wide (internal service only)
M08Surface temperature and fire safety of a hot hearth indoors
M08Floor loading of any thermal mass
M08Na-ion stationary ecosystem maturity and supply concentration
M08Winter PV deficit at high latitude

Sources · M06 + M08

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Nothing leaves.Heat the human,not the air.