Cool Pads

Evaporative cooling for your greenhouse

Evaporative cooling is a method that can be used to lower temperatures in your greenhouse. For many years, the standard way to do this has been through the fan and pad system.

This system relies on exhaust fans to pull air through the large surface area of evaporative cooling pads. As water evaporates, it cools the indoor air as it moves through the cool pads.

As with our heating and ventilation systems, the Williamson Greenhouses team can match a cooling system to your greenhouse to reliably lower the temperature and help maintain a better growing environment. As you would expect, fan and pad systems need to be sized appropriately to achieve maximum cooling efficiency.

Bringing cool air to your greenhouse

In this system, aspen or cellulose pads are mounted in one end wall or a sidewall of the greenhouse. The greenhouse cool pad is supplied with water from a pipe above the pads and excess water is collected in a gutter at the bottom.


Air drawn through the wet pads by fans mounted in the opposite end wall or sidewall is saturated and cools the greenhouse. The pads are sometimes removed for the winter to allow more light to enter the greenhouse.

Steps to greenhouse cooling


  • outdoor air is drawn through cooling pads and enters the greenhouse
  • hot air is exhausted by fans mounted on the opposite end wall of the greenhouse
  • In a properly designed system, the temperature inside the greenhouse can be 10-15 ºF degrees cooler than the outdoor temperature
  • a thermostat controls the cooling system
  • efficiency can be increased with a shade system; the fans will not have to work as hard to achieve the optimum temperature

Give us a call and we will help you find products, resolve problems and help you with whatever else you need. You can depend on us to grow together!