Green Air CTDH-3 Atmospheric Controller (also photo sensor option) 

Designed to turn "On" and "Off" exhaust fans and/or intake fans to remove unwanted atmosphere due to heat or humidity. 

Intended as a cooling and dehumidifying control. This controller is ideal for situations where excess heat and humidity need to be exhausted.

Temperature rise will activate the right outlets and deactivate the left outlets. The right outlets will be on during venting periods to run fans to correct temperature and humidity excesses.

While the unit is performing an exhaust function based on temperature or humidity, your CO2 will be temporarily shut off to conserve CO2. Dual outlet control of CO2 and ventilation. The CT-DH-3(P) Photo Sensor option operates only when lights are on.

More info from the Manufacturer (PDF format - Lots of detail.)