The heat infiltration and temperature disruption caused by opening refrigerated cargo spaces during multi-stop delivery operations. Each door opening introduces warm ambient air, humidity, and radiant heat from surrounding surfaces, requiring the refrigeration system to remove this thermal load to restore target temperature. In South African urban environments with 35-40°C pavement temperatures, a single 60-second door opening can introduce 15-20 MJ of thermal energy into a small cargo space. Multi-stop courier routes with 15-40 deliveries per day experience cumulative thermal loads far exceeding long-haul transport, yet most refrigeration systems are designed and rated for long-haul operations with minimal door openings. Proper door opening protocols, insulated cargo barriers, and oversized refrigeration capacity are essential for maintaining temperature integrity in last-mile operations.
Engineering Formula: For detailed thermal load calculations including multi-stop route examples and equipment sizing requirements, see Door Opening Heat Infiltration in our Technical Formulas Reference.
Related Terms: Last-Mile Cold Chain Delivery, Multi-Stop Delivery (Cold Chain), Temperature Excursion