Thermal Output (BTU)
The amount of heat a rig releases, measured in British Thermal Units per hour.
Because nearly all the electricity a computer consumes is converted to heat, a mining rig's thermal output closely tracks its power draw. The British Thermal Unit per hour is a common way to express that heat: one watt equals roughly 3.41 BTU/hr, so a 400W rig outputs about 1,365 BTU/hr - enough to noticeably warm a small room. This figure matters in two ways for home miners: in winter the heat offsets space heating you would otherwise pay for, while in summer it adds load to any air conditioning. Knowing the BTU output helps you place a rig sensibly and plan seasonal cooling.