A data centre can operate thousands of high-performance processors while producing a continuous stream of thermal energy that its cooling infrastructure must remove. For operators, that heat represents a necessary consequence of computing activity rather than an intended product. For neighbouring buildings, industrial facilities, and district heating networks, the same thermal output could represent an additional energy source. The opportunity becomes more complicated when infrastructure developers attempt to establish how much of that energy reaches a customer in a usable form. A cooling system may extract substantial thermal energy without delivering an equivalent amount of useful heating to another facility. Temperature requirements, pumping demand, heat-pump electricity consumption, distribution losses, and seasonal demand can influence the outcome. These variables create a distinction between recovering thermal energy inside a facility and demonstrating that an external customer actually benefits from it. The central question concerns the quality of the evidence that connects heat extraction with measurable energy delivery.