Higher humidity shows off energy-saving potential of TNC installation

An increasing number of growers acquires installations that allow them to blow outside air or air from above the screen into the greenhouse. In popular parlance, this is called a New Cultivation (TNC) installation. Several growers involved in the Monitoring Energy innovations project, have surveyed the performance of this installation.

With some growers you can clearly see that the TNC system provides added value in the way they regulate the climate. The documented changes generally lead to higher average humidity, really showing off the energy saving potential of the TNC installation. After all, growing at a higher humidity inhibits evaporation and reduces the exchange of air necessary in order to drain the remaining moisture.

There are, however, also examples in which the installation leads to lower humidity. This might be because growers are overdoing it. Dehumidifying might be necessary for a better quality, but it can be counterproductive in as far as it conflicts with heat issues. And sometimes even with crop quality. Growers complain about increased water consumption (difficult in phalaenopsis cultivation) or insufficient climate (unfavourable in vegetable cultivation).

Fortunately, there are also growers who manage to get the most out of their installation. These growers boast better crop performance and lower power consumption. Their climate control sports a strict separation between heating, shading and dehumidification. The pipes are used for heating, regardless of humidity, and thus have no minimum pipe temperature. The screens open and close on the outside, also regardless of the humidity. The dehumidification system is triggered by moisture, regardless of temperature and screen orientation, allowing for more accurate dehumidification.

Just how much moisture should be drained is still somewhat unclear. With the new TNC installations, however, growers are outfitted with enough tools to effectively guide the conditions involved, giving them, through trial and error, the opportunity to gain as much experience as possible.

This project is funded by the Greenhouse as Energy program from LTO Glaskracht Netherlands and the Ministry of Economic Affairs (EZ).

Category: The New Cultivation, humidity and ventilation

Source: Energiek2020.nu

Publication date: Wed 15 Oct 2014