In the freezing Finnish winter, they stay warm by mining Bitcoin.

Finland-based startup SunBit has deployed 30 bitcoin-heating systems, mostly in Finland with one in the Netherlands, that repurpose Bitmain Antminer S21 XP Hydro units (495T, ~5.3 kW) to convert mining power into 60°C water for home heating, with installation costs of $20,200–$31,400 and payback estimated at 3–6 years. Under SunBit's model, a single miner consuming about 46,400 kWh annually at 11 cents/kWh earns roughly 1/12 BTC per year—about $6,100 after a 10% service fee at an $82,000 BTC price—leaving around $900 in surplus after $5,200 in electricity costs, with a breakeven near $70,000 BTC. The economics are fragile: more than half the heat can go unused in mild seasons, air-source heat pumps deliver 2.5–3 units of heat per unit of electricity versus the miner's 1:1, and the 2028 halving—cutting block rewards from 3.125 to 1.5625 BTC—threatens payback for current buyers. SunBit's calculator ignores the halving, and CEO Elmeri Suomi said the company makes no fixed-return promises, leaving customers exposed to bitcoin price and network difficulty. Watch whether SunBit's planned grid-balancing feature and overseas expansion can offset halving pressure on the model.