Cooling and heat: every watt becomes heat
A 3 kW miner is a 3 kW space heater that happens to hash. Cooling removes that heat and costs energy itself — and in winter, the heat itself can be the product.
The conservation law you can't negotiate
Nearly every watt a rig draws exits as heat. 3 kW of mining hardware needs 3 kW of heat removed — by air flowing through, or by the room's temperature rising until the walls leak it out. Cooling overhead is the extra energy spent moving that heat: fans (tens of watts), ventilation (100–300 W), or compression cooling (which can add 20–40% of the IT load).
This overhead belongs in the efficiency number: a 25 J/TH site with 10% cooling overhead is effectively 27.5 J/TH (see the efficiency lesson — always label the boundary).
Heat as a product
- Winter space heating: a rig in the living room offsets heating you would pay for anyway — effectively discounting your power bill.
- Water pre-heating / greenhouses / drying: small chains of hobbyists run rigs as heat sources that pay rent.
- Summer reverses the deal: the same rig now costs its draw PLUS cooling to remove it — plan seasonally.
See it live on pow.family
The electricity calculator includes a cooling-overhead percent — set it to your season and watch the cost floor move.