Correct use of outside air

At the moment the heat and humidity content of the outside air during the daytime can be higher than the growing room air. In this type of situation it is better to use as little of this "unsuitable" outside air as possible, by, for example, setting the CO2 to a higher (maximum) value. This releases more cooling capacity for the room climate, with beneficial effects on evaporation.

At night when the heat and humidity content of the outside air is lower than the growing room air, it is better to use as much of the "suitable" outside air as possible by, for example, setting the CO2 to a lower (minimum) value. This means there is less cooling capacity required for the room climate, which saves energy.

Adjusting the CO2 value can be done manually or automatically via the climate computer settings. If automatic adjustment is chosen do not forget that the settings are based on the outside RH measurements. If the measuring sensors are too dry, control at night may also be based on the maximum CO2 value, which can place an unnecessary load on the cooling system. Good (weekly) maintenance to the outside RH measuring equipment will also help save cooling energy.

Jan Gielen, Specialist climate & energy, C point