In the Finnish Winter, They Mine Bitcoin to Stay Warm

Written by: Shaurya Malwa, CoinDesk

Translated by: Chopper, Foresight News

In a 180-square-meter house in Nokia, Finland, the occupants have completely severed ties with municipal district heating and now rely entirely on Bitcoin mining rigs for warmth.

This equipment is the "Bitcoin boiler" launched by SunBit. For every kilowatt-hour of electricity the mining rig consumes, nearly all the energy is converted into heat. The device stores the thermal energy in water, which can reach up to 60°C, and then circulates it throughout the house via radiators and underfloor heating pipes. Like oil or gas boilers, the machine continuously mines Bitcoin while generating heat.

In simple terms, if the Bitcoin mining revenue covers the electricity bill, homeowners effectively enjoy free heating without ongoing energy expenses. However, the installation cost for this system exceeds $20,000. Profitability hinges on the Bitcoin price, electricity rates, and the competitive difficulty of network-wide hashing.

SunBit founder Suomi stated, "The heating function itself is unaffected by market trends; only the payback period changes."

This model also faces an unavoidable milestone. Bitcoin is projected to undergo its next halving in spring 2028, cutting block rewards in half. Many homeowners may not recoup their equipment costs before the halving arrives, which would directly strike at the feasibility of this "mining-for-heating" business model.

SunBit delivered its first batch of mass-produced Bitcoin boilers in 2025, with 30 systems currently in operation, CEO Elmeri Suomi told CoinDesk in an interview. Beyond one unit installed abroad, all others are located in Finland, having been deployed to replace or reduce reliance on gas, oil, firewood, and municipal district heating.

In 2025, they launched their first overseas project in Lekkerkerk, Netherlands, swapping gas heating for mining rigs. In Kotka, a port city with a population of around 50,000 on Finland's southeast coast, a 200-square-meter residence integrates mining rigs with existing oil boilers to create a hybrid heating system.

Image: A SunBit device installed in a Finnish home

In an old manor in Tampere, Finland's third-largest city, mining rigs replaced wood-burning stoves, maintaining a 1,500-liter water tank between 50°C and 60°C. A similar heating setup operates in a 3,000-square-meter industrial facility in Vimpeli, paired with an air-source heat pump that also absorbs surplus power from a 30-kilowatt solar panel array.

Finland has emerged as a testing ground for heating powered by mining rig waste heat. Domestic company MARA also captures waste heat from miners and channels it into the municipal heating grid to warm local residents.

This SunBit solution targets everyday consumers: homeowners purchase the mining rigs independently, occupy the space formerly held by traditional boilers, retain full ownership, pay their own electricity bills, and keep all mined Bitcoin. Because mining rigs generate significant noise, they are typically housed in basements or dedicated soundproof rooms.

The Economics of a Single Mining Rig

Taking the homeowner in Nokia as a case study, the core calculation boils down to a straightforward income-versus-expense comparison: whether mining revenue can offset electricity costs.

SunBit's modeling framework utilizes the Bitmain water-cooled Antminer S21 XP Hydro, delivering 495T hashrate and running third-party firmware Braiins OS. Operating continuously 24/7 at approximately 5.3 kW, the device consumes roughly 46,400 kWh annually. At an electricity rate of 11 cents per kWh, the yearly power cost totals approximately $5,200.

Assuming a Bitcoin price of $82,000 and a network hashrate of 1040 EH/s, a single rig would mine approximately 1/12 of a Bitcoin per year. After deducting SunBit's 10% service fee, the homeowner retains Bitcoin valued at roughly $6,100; the mining pool then charges an additional 0.5% handling fee.

This service fee is optional and covers 24/7 remote monitoring, automatic strategy adjustments tracking Finland's floating electricity tariffs, a companion mobile app, and future grid peak-shaving capabilities. Declining this service allows homeowners to keep the full 1/12 BTC, worth approximately $6,800 annually.

Opting for the paid service still leaves a net surplus of about $900 after electricity costs, making the accompanying heating essentially free. Naturally, standard residential buildings cannot absorb all the heat output generated by the rigs.

Suomi told CoinDesk, "Currently, the mining revenue generated per kilowatt-hour slightly exceeds the electricity tariff, meaning heat is fundamentally a free byproduct." At the time of publication, Bitcoin was trading near $81,500. SunBit's break-even point (where post-service mining revenue exactly matches electricity costs) sits around $70,000. This threshold excludes initial hardware costs and assumes a static network hashrate. As more rigs come online, individual profitability will inevitably decline.

Suomi shared a mining pool backend screenshot from an early adopter who purchased the 358T water-cooled S21+ Hydro. Over the past year, it yielded 0.039 BTC, worth approximately $3,160 at prevailing market rates. This equipment replaces roughly 2,000 liters of heating oil annually. SunBit can only access data from its initial pilot group; subsequent clients operate through independent private pool accounts, leaving the platform blind to their performance metrics.

Better Than Oil Boilers, But No Match for Heat Pumps

SunBit provided journalists with a comparative breakdown: a detached home consumes 2,300 liters of heating oil annually. At roughly $2.19 per liter, the annual fuel expenditure reaches about $5,000.

Switching to mining rig heating could theoretically eliminate this fuel cost. Modeling indicates a net annual surplus of approximately $920 after electricity deductions. Complete system installation runs around $20,200, excluding optional add-ons. Excluding maintenance and loan interest, the payback period stretches roughly 3.5 years. Residents can retain their original oil boilers as backups during peak cold spells.

Yet a critical limitation exists: over half of the generated heat goes unused indoors. The equipment's external dry cooler (a fan-assisted cooling module) vents surplus thermal energy directly outdoors, a problem particularly acute in summer (late May to mid-September in southern Finland). Finland boasts a lengthy heating season; southwestern winters endure roughly 100 days, while Lapland faces up to 200 days of arctic conditions.

Air-source heat pumps represent a far stiffer competitor. For every kilowatt-hour of electricity consumed, a heat pump extracts thermal energy from ambient air or soil, yielding 2.5 to 3 times that amount in heat. Conversely, a mining rig converts 1 kWh of electrical input strictly into 1 kWh of thermal output.

To illustrate: a house requires 25,000 kWh of heat annually. SunBit calculates that operating an air-source heat pump costs roughly $1,100 yearly, versus approximately $3,170 for municipal district heating. If a mining rig does not run continuously but instead modulates output to precisely meet the 25,000 kWh heating requirement, net mining profits after electricity payments would generate an extra $490.

The trade-off is transparent: heat pumps draw less power and deliver superior thermal efficiency, while mining rigs consume more electricity but leverage mining profits to neutralize utility bills. A rig's competitive edge derives solely from cryptocurrency profitability, not inherent heating efficiency.

Suomi emphasized that mining rigs excel during severe cold snaps: "Rig heat output remains impervious to outdoor temperatures. Air-source heat pumps suffer drastic efficiency drops at -25°C, but miners operate consistently: across all 365 days of the year, every kilowatt-hour reliably converts to heat topping out at 60°C." However, operational gains from mining are tethered to Bitcoin market dynamics and global hash rate difficulty, whereas heat pumps remain entirely insulated from crypto volatility. Full system installation ranges from $20,400 to $31,400, with projected payback periods spanning 3 to 6 years.

The 2028 Halving Poses the Greatest Risk

Customers ordering installations today will likely encounter the 2028 Bitcoin halving well before breaking even. Block rewards will contract from 3.125 BTC to 1.5625 BTC.

SunBit's revenue calculator ignores halving impacts, projecting payback solely on current mining yields. Regardless of whether Bitcoin trades at $100,000 or $20,000, the company guarantees no fixed returns.

Suomi remarked, "I do not forecast coin prices or hash rate trajectories. We transparently outline halving history to every client, detailing how previous halvings have historically squeezed margins."

Preserving baseline calculation parameters, post-halving mining revenue per kilowatt-hour will plummet from 13 cents to 7 cents, falling beneath the 11-cent electricity rate. At that juncture, homeowners will bear heating costs out-of-pocket, driving the price per kWh of heat to roughly 4 cents—nearing the operational expenses of a comparably efficient air-source heat pump.

Households equipping this technology this winter retain approximately 18 months to capitalize on current high-margin conditions. Extrapolating from this mathematical framework: to sustain "free heating" beyond the 2028 halving, Bitcoin valuations must climb to approximately $131,000.

Consequently, these dozens of residences across Finland have adopted a highly unconventional warming strategy: banking on relentless Bitcoin bull markets.