Also known as a pad and fan system, uses fans and wet pads to cool a greenhouse. The system works by blowing air out of the greenhouse with large fans, which creates a suction that pulls hot air from outside through the wet pads. As the air passes through the pads, water evaporates into it, which lowers the temperature and increases the humidity. The excess water is collected at the bottom of the pads and returned to a tank for reuse.

Greenhouses are vulnerable to overheating from spring until autumn. Without protection from heat, few plants are likely to survive unharmed when subjected to prolonged high levels of heat and dry atmosphere within a greenhouse or conservatory. However, with sufficient air circulation, humidity and shading, many plants will tolerate high summer greenhouse or conservatory temperatures in the same way that they survive in the tropics and subtropics where many greenhouse and conservatory plants originate. The aim of gardeners is to prevent leaf temperature rising to levels at which tissue damage occurs. By September, shading should be reduced gradually, and removed as soon as ventilation alone can control overheating. Blinds and netting used for shading can be deployed on cold winter nights to limit heat losses.