A Bitcoin miner turns almost all of its electricity into heat. That is why miners love cold places, and why winter changes the maths for home miners too. Here is the science, the risks and the numbers.
By Michal Beno, CEO, OneMiners31 October 2026
A Bitcoin miner turns nearly 100% of its electricity into heat. Getting rid of that heat costs money and limits how hard the machine can run. In cold places, outside air does most of the cooling for free, machines stay inside their safe temperature range, and many cold regions also have cheap hydro power. That is why Norway, Finland and Canada are mining hubs. OneMiners runs sites in all three, from 4.4 cents per kWh prepaid. For home miners, winter has one more twist: the heat can warm a room, though the noise does not go away.
12,539
BTU per hour from one Antminer S21 Pro
2.5x
the heat of a 1,500 W space heater
89%
of Norway's 2024 electricity came from hydro
4.4 cents
OneMiners prepaid price in Norway and Finland
Antminer S21 Pro rating, OneMiners catalogue; Ember, Norway 2024; oneminers.com/pages/hosting-centers, 27 October 2026.
KEY TAKEAWAYS
A Bitcoin miner is a heater that earns Bitcoin
Inside every Bitcoin miner, chips called ASICs make hundreds of trillions of guesses per second. All that work moves electricity through tiny transistors, and the energy ends up as heat. A miner does not store energy or move anything heavy. So the electricity that goes in comes out as heat, through the fans as hot air or through the water loop as hot water.
WATTS IN = HEAT OUT
Heat (BTU per hour) = power (W) x 3.412
Heat per day (kWh) = power (W) x 24 / 1,000
Antminer S21 Pro: 3,675 W x 3.412 = about 12,539 BTU per hour, or 88.2 kWh of heat a day
How much heat does each Bitcoin miner make?
Antminer S23 318TOneMiners calculation: watts x 3.412. Space heaters = how many 1,500 W heaters give the same heat. Power ratings: OneMiners catalogue, 27 October 2026.
How many space heaters is one Bitcoin miner?
Heat output compared with a 1,500 W electric heater (longer bar = more heat)
OneMiners calculation from rated power. A miner runs 24 hours a day, so it gives this heat all day, every day.
Why cold air makes mining cheaper
Every mining site has two jobs: run the machines and move their heat out. In a hot place that second job needs big fans, evaporative walls or air conditioning, and all of it uses power. Air-cooled models like the Antminer S21 are rated to run in intake air up to about 40 to 45 C. Reviews found they start slowing down near the top of that range to protect their chips. On a hot day, a hot site can lose hashrate.
In a cold climate the outside air is already cool for most of the year. Data-centre engineers call this free cooling: you mostly just move cold air in and warm air out. Design work for Finnish data centres found free cooling works for most of the year there. Our guide to where air cooling runs out shows the physics.
The Nordic advantage: cold air plus clean, cheap power
Cold alone is not enough. A mining site also needs a lot of stable, affordable electricity. The Nordic countries and Canada have both. In 2024 about 89% of Norway's electricity came from hydropower, according to the energy think tank Ember. Hydro is steady day and night, which suits machines that run 24 hours a day. Read more about where Bitcoin mining gets its power.
What does power cost at cold-climate OneMiners sites?
US cents per kWh, 7-year prepaid (shorter bar = cheaper)
oneminers.com/pages/hosting-centers, 27 October 2026. Online-ordered miners: 6.4 cents in Norway and Finland, 6.8 cents in Canada. Norway also has 15 MW incoming.
At OneMiners, the Norway Arctic site runs 36 MW with 15 MW more on the way, Finland runs 22 MW, and Canada 36 MW. All three offer 7-year prepaid power at 4.4 to 4.7 cents per kWh, among the lowest prices in the network.
Winter is not all good: four cold-weather risks
Cold climates help, but professional sites still manage winter carefully. These are the main risks:
Condensation
Bitmain rates its machines for 10 to 90% humidity, non-condensing. Warm, wet air meeting cold metal makes water, which can damage boards.
Frozen or blocked intakes
Snow and ice can block air inlets. Sites use filters, louvres and recirculated warm air to stop it.
Coolant that is too cold
Hydro miners like the S21 Hyd series expect coolant between about 20 and 50 C. Too-cold water must be warmed up first.
Winter power prices
In some places home electricity costs more in winter. A fixed hosting price removes that risk.
These are exactly the details a hosting team handles for you. Our guide to air, hydro and immersion cooling explains how each system copes.
Worked example: a Bitcoin miner as a home heater
Say you mine at home with an Antminer S21 Pro in winter. It uses 3,675 W and puts out 88.2 kWh of heat a day. If you would otherwise heat that space with electric heaters, the miner's heat replaces heater electricity one for one. During those hours, the mining is almost free, and the machine earns about $8.75 a day in Bitcoin at today's numbers.
The catch: you need 88 kWh of heat every single day, about 2.5 heaters running nonstop. Most homes need far less, and only in winter. And an air-cooled S21 Pro is about 75 dB, like a vacuum cleaner. In summer you pay full price for power and get heat you do not want. Read the 75 dB problem before trying it. For most people, a hosted miner in a cold climate gets the same benefit without the noise.
Antminer S23 Hyd - 580 TH/s
Water-cooled, 9.5 J/TH. Hydro loops move heat efficiently.
View miner
Sealminer A4 Ultra Hyd - 886 TH/s
9.45 J/TH water-cooled. 886 TH/s in one unit.
View miner
Antminer S21 Pro - 245 TH/s
Air-cooled, 15 J/TH. Loves cold intake air.
View minerCold climates and cheap hydro power are a natural match for Bitcoin mining, and that is where OneMiners has built. Our Norway Arctic, Finland and Canada sites sit alongside 14 more locations, for 1,964 MW of capacity and 98%+ average uptime. Power starts from 3.6 cents per kWh on a 7-year prepaid plan. You choose the site and own the Bitcoin miner. We handle the cooling, the snow and everything else.
Frequently asked questions
Do Bitcoin miners work better in cold weather?
They run more reliably: cool intake air keeps chips below the temperature where they slow down, and cooling costs less power.
How much heat does a Bitcoin miner produce?
About its power in watts x 3.412 BTU per hour. An Antminer S21 Pro at 3,675 W makes about 12,539 BTU per hour.
Can I heat my house with a Bitcoin miner?
You can heat a room, and that heat replaces heater electricity. But miners are loud, and you pay full power price when you do not need the heat.
Why is Bitcoin mining popular in Norway?
Cold air for cooling and plenty of hydropower. About 89% of Norway's electricity came from hydro in 2024.
Can it be too cold for a Bitcoin miner?
Yes. Condensation, iced-up intakes and coolant below about 20 C for hydro models all need managing.
Let the cold do the cooling. Host your Bitcoin miner where it runs best.
See hosting locationsBrowse Bitcoin minersSOURCES AND DATA
- Bitmain S21 XP specification (humidity, storage temperature, altitude): support.bitmain.com
- Antminer S21 ambient temperature behaviour: Hashrate Index S21 review and CryptoSlate review release, 2024
- S21 Hyd coolant inlet range: Bitmain S21 Hyd specification
- Norway electricity mix 2024: Ember, Norway country profile
- Free cooling in Finland: Sweco, Air data centre design project
- Miner power ratings: OneMiners catalogue, 27 October 2026
- OneMiners locations, capacity, power prices and uptime: oneminers.com/pages/hosting-centers, 27 October 2026
Michal Beno
CEO of OneMiners, the global Bitcoin mining hosting and hardware platform with 17 published hosting locations, 7-year fixed electricity contracts and a 7-year hardware warranty. He writes about the economics of industrial Bitcoin mining.
Informational only, not financial advice. Figures are a snapshot from public market data, news reports and the OneMiners catalogue as of 27 October 2026 and can change quickly. Net-per-day figures are at today's numbers, before pool fees, and are not a forecast. Crypto prices can fall as well as rise. No return is offered or implied. Do your own research.
