SAUNA. / M4 thermal readiness study
Study basis. Results require a controlled physical test.
M4 thermal readiness study
M4 Thermal Readiness Study.
Measuring time-to-bath readiness with compute-driven pre-warming versus a cold start.
A cold sauna requires the stove to warm timber, glass, benches, and stones from ambient conditions.
This study asks whether directing approximately 1.1 kW of recovered compute heat into the structure creates a measurable improvement in readiness—and whether total preparation energy changes across the full cycle.
No result is assumed before controlled physical measurement.
Cold start control.
Compute pre-warm.
Stove completes the lift.
Total energy measured.
The question
What changes when M4 starts first?
The stove remains the bathing heater and remains responsible for stones, steam, and löyly. M4 only raises the starting condition with lower-temperature recovered heat.
Faster readiness is the core metric. Energy claims follow only if the complete measured preparation cycle supports them.
Scenarios
Compare starting conditions.
| Scenario | Starting condition | Final heating |
|---|---|---|
| Cold start (control) | The sauna follows ambient site conditions. | The stove performs the complete lift from cold to bathing temperature. |
| Scheduled pre-warm | M4 runs for a defined period before planned use, using recovered heat to raise the starting condition of timber, glass, and air. | The stove completes the lift from the warmer starting condition. |
| Maintained baseline | M4 operates when useful heat demand aligns, holding a steadier baseline in M3 and the M1 structure and reducing cold-soaking. | The stove completes the lift when bathing heat is required. |
AI inference and Bitcoin network computation may supply the same electrical input. Thermal yield at that input does not depend on the calculation; operating pattern does.
Measurement
Measure the complete preparation period.
Total preparation energy records combined M4 and stove input from the start of preparation until bathing temperature is reached—not stove runtime alone.
Total Preparation Energy = ∫ from t₀ to t_bath of (P_M4 + P_Stove) dt
| Variable | Recorded basis |
|---|---|
| Ambient | Outdoor temperature and site conditions. |
| Surfaces | M1 and M3 air and surface temperatures, including relevant thermal mass. |
| M4 input | Compute electrical input, runtime, and electricity used. |
| Air path | Airflow, intake/outlet delta-T, and heat-path condition. |
| Stove input | Stove power, operating duration, and electricity used during the final lift. |
| Readiness | Time to the selected bathing temperature across the preparation window. |
| Total energy | Combined M4 and stove electricity for the complete preparation period. |
Claim boundaries
Readiness and energy are separate.
| Measure | Interpretation |
|---|---|
| Faster readiness | Core metric. A warmer starting condition may reduce the time required for the stove to reach bathing temperature. |
| Total electricity | Energy reductions are stated only when physical measurement supports a net-positive result across the full preparation cycle. |
| Site specificity | Climate, envelope, ventilation, thermal mass, heat path, and operating pattern prevent one result from becoming a universal figure. |
| No assumed result | No thermal, computational, or monetary result is assumed before controlled physical measurement. |
M4 does not replace the stove, generate steam, or promise zero-cost heat. Savings and readiness gains are stated only when measurement supports them.
Reference installation
A defined input and heat path.
| Element | Reference basis |
|---|---|
| Integration | Reference installation in a ventilated service zone beneath the M3 changing-room bench. |
| Computer | Air-cooled unit at approximately 1.1 kW electrical input, with corresponding recovered-heat output, subject to final test equipment. |
| Air path | Cooler intake air and controlled warm-air routing to M1, the M3 changing room, or another useful thermal load. Automated bypass when heat is no longer required. |
| Stove | Independent bathing heater responsible for bathing temperature, stones, steam, and löyly. |
| Workload | AI inference, Bitcoin network computation, or another suitable workload may be used. Thermal yield at the same electrical input does not depend on the calculation. |
An adjacent or external technical-compartment arrangement requires its own reviewed heat path. Heat loss and response may differ from the M3 bench reference.
Project review
Confirm the complete system.
| Review | Basis |
|---|---|
| Electrical | Supply, protection, isolation, controls, and compatible equipment. |
| Thermal | Output, temperature limits, retention, routing, and bypass when heat is no longer useful. |
| Failsafe | Temperature limits, automatic throttling or shutdown, and controlled airflow. |
| Physical | Airflow, enclosure, clearances, humidity, acoustics, and service access. |
| Operation | Schedule, monitoring, failure states, maintenance, and responsibility. |
| Stove separation | M4 does not remotely operate the sauna stove. Stove operation remains subject to its approved control and safety system. |
M4 is included only where recovered heat has a planned use and the electrical, thermal, physical, and operating arrangement is confirmed.
Remote operation starts M4 only. It does not start or control the sauna stove.
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