To optimally control the indoor climate and minimize energy consumption, more and more tomato growers are opting for dehumidification with air handling units (AHUs). Currently, Technokas is again implementing this self-developed climate system at five major tomato growers. In total, this 'Next Generation Growing' system from Technokas is already running in more than 100 hectares of tomato greenhouses in the Netherlands.
Technokas introduced their Next Generation Growing system some 15 years ago. At that time, it was also used by some tomato growers, but still without a heating block. After that, the use of AHUs with heating blocks took off, especially in ornamental plant cultivation. In recent years, more and more vegetable growers have discovered this highly effective climate system. The basis of the system is the air handling unit that blows conditioned outside air into the greenhouse. Technokas integrates this air handling unit in the greenhouse wall or, for a few years, in the greenhouse roof. In addition to the fans and valve registers, each AHU contains technical facilities for - as desired - cooling, heating, and/or filtering the air. Moreover, Technokas can run the same fan at different flow rates per project, at more or less rpm, which also means it uses more or less electricity. The company is now increasingly applying this feature to tomato growers, who are increasingly opting for the AHU system. Several growers, where AHUs are now being installed for the first time, are considering having this system installed in other greenhouses as well.
Duijvestijn Tomatoes
The most recent project, for which installation work will start in week 47, is Duijvestijn Tomaten. By the end of this year or early 2025, this grower too plans to benefit from the AHUs that Technokas will install above the centre aisle. The installations will be in an existing tomato greenhouse of over 3 hectares. A total of six double AHUs will hang in this greenhouse every 24 meters. At 5.6 m³/m²/hour, these deliver a slightly higher capacity than the standard capacities installed by Technokas at other growers. But the construction and operating principle is the same; an AHU with a recess in the deck, a heating block, valves, fans, and trunks. The installation of the system coincides with an extensive renovation of the greenhouse, which will be updated in terms of substrate, heating, and growing gutters.
Van Adrichem Nurseries
Another recent project where Technokas installed air handling units is at Van Adrichem Kwekerijen in Westdorpe, Zeeland. This grower built a new 7-hectare greenhouse and chose AHUs. Most of the greenhouse is 235 meters wide, but there is also a corner where the greenhouse is only half as long. At the spot where the greenhouse is full width, Technokas installed 11 double AHUs above the middle aisle. At the part of the greenhouse that is half as long, 4 single AHUs are installed at the end wall. In total, all AHUs together contain 26 fans with valves, heating blocks, and trunks. Each fan in this system can then condition around 2,820 m² of cultivation area. They do this with a flow rate of 14,100 m³/hour, which is about 5 m³/m²/hour.
The Valley
Technokas is also installing AHUs at The Valley's growers. This is happening at the Base Valley location, their new headquarters on the Kreekrug in De Lier. Here, 12 double AHUs were hung at the new building project in week 29. This was done immediately after glazing the deck, and just before retracting the screen wires. This is a greenhouse of just under 8 hectares, where the double AHUs are also mounted above the center aisle. In the 275-meter-wide greenhouse, the trunks attached to the AHUs have a length of the full cultivation paths, in this case, 133 meters. Throughout the greenhouse, there are a total of 24 fans with valves, heating blocks, and trunks. They condition a cultivation area of about 3,300 m² per fan with a flow rate of 16,200 m³/hour, which also works out at about 5 m³/m²/hour.
Red Harvest
Earlier this year, Technokas went to work for two Red Harvest greenhouses, in which air-handling units were installed above the center aisle during the new construction. These are greenhouses no. 5 and no. 6 on the Tussenweg in Middenmeer. There, Red Harvest has now realized six identical 'blocks' of greenhouses, each measuring about 7.5 hectares. The greenhouses are 255 meters wide, making the trunks above the cultivation paths about 123 meters long. In greenhouse No. 5, the installation was completed earlier this year, so tomato cultivation is already in full swing. Greenhouse No. 6 is currently being completed. There, Technokas installed the AHUs in week 25 and will hang the trunks in week 44. Each greenhouse has 12 double AHUs. This means that here, too, each greenhouse has 24 fans with valves, heating blocks, and trunks. This condition is approximately 3,100 m² per fan with a flow rate of 15,300 m³/hour and thus also approximately 5 m³/m²/hour. Red Harvest alternates the cultivation of tomatoes and cucumbers in its greenhouses.
Schenkeveld
At the Schenkeveld tomato nursery in Rijsenhout, near Schiphol Airport, Technokas already installed AHUs in three 11-hectare greenhouses in recent years. This happened twice during new construction and recently also in an existing greenhouse during the crop rotation. The first two new-build greenhouses involved projects for growing tomatoes without lighting. The two existing greenhouses, one of which was therefore already equipped with AHUs, were also fitted with LED lighting. For this very reason, Schenkeveld wanted to hang the AHUs. The LED lighting replaces the SON-T lamps that used to hang there. Because of this replacement, heat production via the lighting is suddenly much lower, which in turn can cause moisture problems. With the AHUs, Schenkeveld eliminates this problem again. This year, Technokas will therefore also equip the last existing greenhouse at this nursery with AHUs.
Each of the four greenhouses will eventually have 16 double AHUs. Here, they hang between the lattices above the crop. That means there are 32 fans active per greenhouse with valves, heating blocks, and trunks. In these greenhouses, the trunks are 75 to 80 meters long; half the length of a cultivation path. The greenhouses here are 320 meters wide in total. As a result, each fan here also conditions about 3,000 m² of cultivation area with a flow rate of 15,000 m³/hr, which is about 5 m³/m²/hour.
For more information:
Technokas
Leehove 33
2678 MA De Lier
Tel: (0174) 24 05 45
[email protected]
www.technokas.nl