Arch Lending × Lyn.Sauna
Liquidity meets longevity
A case study in Bitcoin-powered wellness infrastructure.
Merging physical and financial health under one philosophy:
What matters, lasts.
INTRODUCTION
Born from the Nordic ritual of sauna - a practice of patience, clarity, and renewal.
Lyn.Sauna merges Scandinavian architecture with Bitcoin’s open-source principles. Instead of seeing mining heat as waste, the system redirects thermal output into the sauna’s airflow, transforming excess energy into restorative warmth.
By asking “How can we harness excess heat?” rather than “How do we repurpose it?” the design reframes energy as a regenerative, circular resource.
Each sauna unit integrates an optional Bitcoin mining heat module, generating both steady thermal pre-warmth and verifiable Bitcoin rewards. This dual-output model reduces overall power consumption and supports the proof-of-work network.
To fund the development and production of Lyn.Sauna while remaining long Bitcoin, Lyn leverages a BTC-collateralized loan from Arch, ensuring the project grows without selling BTC or diluting ownership. Critical risk management is applied to ensure a 50% LTV even at a harsh collateral value decline.
Lyn.Sauna is built on sound money, sound energy, and sound health - designed for longevity at every layer.
THE PROBLEM
Every year, data centers and wellness facilities release terawatt-hours of unused heat. Modern glass saunas, while visually striking, lose heat rapidly and require constant high-power input to maintain temperature.
Bitcoin mining, conversely, converts electricity into network security - producing a stable stream of heat that is typically discarded through cooling systems.
Both contexts reveal the same imbalance:
Energy without continuity. Value without regeneration.
Wellness offers restoration but no monetary return. Mining offers monetary return but wastes thermal value.
Lyn.Sauna resolves the split.
By integrating a mining unit directly into the thermal system, the sauna maintains a pre-warmed baseline while validating transactions. Each session restores the body and contributes to the global proof-of-work network.
THE SOLUTION
Lyn.Sauna transforms computation into comfort through a dual-purpose heat system and designed in collaboration with Groundwork.
Architectural Design
The core sauna (2.2 × 3.3 m) reflects Scandinavian minimalism:
- black timber exterior
- organic interior curves
- horizontal untreated timber benches
- panoramic glass wall
- slate-edged roof anchoring the structure into nature
Modular System (M1–M5)
- M1 - Core sauna
- M2 - Cold plunge dock
- M3 - Skylit changing room
- M4 - Bitcoin mining heat module (Antminer S19)
- M5 - Outdoor shower
Mining Module Performance (M4)
At the center lies a Bitmain Antminer S19 housed in a precision-engineered heat-exchange unit.
Thermal & computational output:
- 95–110 TH/s
- ~3250 W
- ~11,000 BTU/hr
- Pre-warms sauna to ~40°C before the stove is engaged
- Reduces stove load by up to 30%
- Saves ~150–225 kWh annually
- Generates ~0.014 BTC/year (≈ $1,400 at $100k/BTC)
This creates a closed-loop system where energy becomes utility, and utility becomes proof.
Discover the Sauna:
lyn.saunaTHE ECOSYSTEM
Lyn.Sauna operates fully on the Bitcoin standard with an ecosystem of aligned partners:
Arch Lending - Secure Bitcoin Financial Products
Arch empowers Lyn.Sauna and its clients to access non-dilutive capital by collateralizing Bitcoin (BTC) through archlending.com, preserving the upside potential of BTC holdings while enabling liquidity for development and ownership.
For Lyn.Sauna, Arch Lending provides the capital needed for design development, materials sourcing, and prototyping without selling BTC, ensuring the project remains aligned with Bitcoin’s ethos of ownership and long-term value retention.
Arch’s secure custody structure guarantees collateral safety, offering instant liquidity while maintaining full transparency and control for the borrower.
For clients, Arch Lending offers a seamless way to finance their Lyn.Sauna purchase without liquidating their Bitcoin.
By using BTC as collateral, clients can borrow funds (in fiat or stablecoins) to cover the cost of the sauna.
Loan terms typically range from 6 to 24 months, with competitive interest rates (indicative rates of 9.5–12.5% APR, subject to market condition).
Clients deposit their BTC into cold storage with a qualified bank grade and insured custodian, where it remains securely held while they repay the loan in manageable installments. This structure allows clients to “stay long Bitcoin,” benefiting from potential BTC price appreciation while enjoying the sauna’s wellness and mining rewards.
For example, at a BTC price of $100,000, a client could get a loan at 60% LTV, retaining their Bitcoin exposure while spreading payments over time.
Arch’s transparent terms and non-recourse lending ensure clients maintain control, with no risk of forced liquidation as long as payments are met and LTV levels are monitored.
This financing model reflects Bitcoin’s principle of sovereignty: clients and Lyn.Sauna alike avoid fiat debt traps, preserve their BTC stack, and invest in a regenerative asset that generates both wellness and digital value. For white glove introduction visit: http://archlending.com/lyn
Together, these contributors form a circular, sovereign design ecosystem - bootstrapping real-world infrastructure without dilution or fiat dependence.
USE CASES
1. Private Installation
A single-unit Lyn.Sauna placed beside a residential coastline property demonstrates the balance between form and function.
The integrated mining module sustains a constant 40 °C baseline, allowing almost immediate session activation without full pre-heating - cutting energy use by nearly one-third across a typical year.
In this context, the sauna becomes part of a daily rhythm:
a quiet cycle of heat, verification, and recovery. Each session represents both proof-of-work and proof-of-life - a simple system that rewards discipline through renewal.
2. Communal Installation - Lyn.Sauna.Retreat
Lyn.Sauna.Retreat extends the principle of regeneration beyond the individual.
The model envisions 21 locations worldwide, each situated in quiet, natural surroundings, lakesides, coastlines, and forests, where mining-integrated saunas host small groups for restorative sessions.
Bookings and transactions occur natively in Bitcoin, with an average rate of 210 DKK per session (up to four guests).
Each site generates both network security and shared yield, distributing BTC proceeds between partners and local operators.
In the Nordics, where renewable energy surpluses reach 10–15 TWh/year (Nordic Grid Development Perspective, 2025), these clubs act as flexible energy consumers, stabilizing local grids while producing measurable wellness and verifiable value.
Annual projections estimate roughly 0.014 BTC in mining rewards (≈ $1,400 at $100,000/BTC), alongside $50,000+ in session-based revenue - forming a self-sustaining circular economy that ties treasury growth to community well-being.
3. Commercial Integration
Within a boutique Nordic resort, Lyn.Sauna replaces conventional heating with mining-integrated thermal systems, combining hospitality with Bitcoin infrastructure.
The result is both aesthetic and energetic refinement: approximately 30% less power consumption, and every joule of heat repurposed into wellness.
Guests experience seamless warmth, unaware that each session quietly contributes to the validation of global transactions; as decentralised hospitality.
Here, Bitcoin becomes invisible; design and sovereignty converge beneath the calm surface of comfort.
Bitcoin disappears into design; sustainability and sovereignty coexist beneath the surface of comfort.
IMPACT / OUTCOME
With this Lyn.Sauna demonstrates how energy, value, and wellness can coexist in balance by transforming excess into utility, and utility into proof.
1. Energy Efficiency
Through mining-integrated preheating, each sauna session reduces primary power consumption by 25–30%, lowering electricity use from 6–9 kWh to 4.2–6.3 kWh.
Over 100 sessions per year, this equates to an energy saving of 180–270 kWh annually, corresponding to $36–54 in direct cost reduction (at $0.20/kWh average Nordic rate) and 90–135 kg CO₂ emissions avoided.
2. Financial Circularity
Each unit’s mining system (Bitmain Antminer S19, 95–110 TH/s, 3250W) produces approximately 0.014 BTC annually - valued at ~$1,400 under a $100,000/BTC market rate.
This offsets hardware costs within a year, creating a regenerative feedback loop: mining funds maintenance, while heat sustains operation.
3. Architectural Longevity
Designed by Morten Bo Jensen in collaboration with Groundwork, each Lyn.Sauna module reflects Scandinavian craftsmanship and modular adaptability.
Built to endure coastal climates, the structures integrate black-timber exteriors, organic interiors, and slate roofs - reducing maintenance cycles and extending lifespan.
4. Environmental Integration
In regions with renewable surpluses, such as the Nordic grid’s 10–15 TWh/year excess, each unit functions as a dynamic energy consumer - absorbing power during low-demand cycles and returning heat to the local environment with near-zero waste.
5. Proof of Concept
The project validates the possibility of Bitcoin as regenerative infrastructure, not extractive speculation.
By redefining mining as both computation and contribution, Lyn.Sauna turns a digital process into tangible community value - measurable in energy saved, Bitcoin earned, and well-being restored.
CONCLUSION
Lyn.Sauna bridges two trillion-dollar industries - wellness and energy - through Bitcoin’s proof-of-work foundation.
It redefines mining from an extractive process into regenerative infrastructure, converting thermal waste into measurable wellness and financial return.
Each installation is seen as a node of sovereignty; self-sustaining, verifiable, and timeless by design. Built on sound money, sound energy, and sound health, Lyn.Sauna represents not just a product, but a showcase for how Bitcoin can power the physical world.
In a world driven by short-term gain, Lyn.Sauna exemplifies a simple truth:
What matters, lasts.
SOURCES
- ArchLending - BTC Collateralized Loans: ArchLending Blog (2025). "Crypto Tax Loss Harvesting" – Details non-dilutive lending for BTC holders, preserving upside without taxable sales.
Arch Crypto-backed loan by Arch
- ArchLending - Sovereignty in Lending: ArchLending Blog (2025). "Bitcoin vs S&P 500" – Explains BTC-backed loans avoiding taxable events, maintaining long-term ownership.
Arch Crypto-backed loan by Arch
- Theya - Multisig Vault Security: Theya Research (2024). "If The US Wanted To Build A Bitcoin Reserve, How Would It?" – Outlines modular multisig for sovereign custody, hedging fiscal risks.
Joe Consorti If The US Wanted To Build A Bitcoin Reserve, How Would It?
- Flash - Instant BTC Payments: Flash Guide (2025). "Bitcoin Payments in Retail: How Steak ’n Shake Saw Sales Rise 11%" – Case study on fee-free, wallet-to-wallet transactions boosting revenue 11%.
Olivia Carter Bitcoin Payments in Retail: How Steak ’n Shake Saw Sales Rise 11% • Flash
- 21Energy - Mining Heat Reuse: 21Energy Blog (2024). "The Ultimate Bitcoin Heating Guide" – Validates 20-30% efficiency via miner waste heat, turning costs into regenerative value.
Maximilian Obwexer Bitcoin Heating Guide: How Bitcoin Heaters Power the Energy Transition — 21energy