Wärmelast

Wärmelast (thermal load) is the amount of heat that must be removed from a system to maintain a target temperature, or the heat energy generated within a system that contributes to its thermal stress. The term is used in several engineering disciplines and has different practical meanings depending on the application.

In buildings and HVAC, Wärmelast refers to the total heat gains that a cooling system must offset. This includes internal gains from occupants, equipment, and lighting, as well as external gains from solar radiation and outdoor temperatures. It is typically expressed in watts or kilowatts and is used to size air-conditioning units, cooling infrastructure, and related building components. Calculations rely on climate data, occupancy patterns, equipment efficiency, and construction properties such as insulation and glazing.

In electrical engineering, Wärmelast denotes the thermal load that electrical components must withstand due to current flow. Heat generation follows the relation P = I^2R, where I is current and R is resistance. The allowable Wärmelast determines permissible operating currents and necessary cooling or derating to prevent overheating, insulation damage, or reduced component lifespan. Thermal models and temperature rise limits, together with ambient conditions, inform the design of cables, transformers, power electronics, and semiconductor devices.

In practice, Wärmelast is a key parameter for reliability and energy efficiency. It is estimated from design data, simulations, and sector-specific standards. The concept corresponds to the English terms “thermal load” or “heat load,” and the German usage reflects its central role in thermal management across disciplines.