A larger cooling package is worth investigating when it can deliver additional crop value or reduce operating costs over the complete production season. The purchase decision needs evidence for that extra value. Installed cooling capacity alone cannot supply it.
For a high-wire tomato project, compare the proposed package with both the lower-capacity option and a credible vented baseline. Keep the cultivar, growing area, production calendar and buyer specification consistent. Otherwise, an apparent equipment advantage may come from a different crop plan.
What a full-season comparison changes
A Dutch experiment at Bleiswijk ran from December 2007 to November 2008 with Capricia tomatoes grafted on Emperador. Four 144 m² Venlo compartments each received one cooling package; climate treatments began in March. Qian and colleagues reported these rounded results in their 2011 study, reproduced in Chapter 2, Table 2 of Qian’s doctoral thesis.
| Package | Installed thermal cooling, W/m² | Fruit at week 48, kg/m² | CO₂ supplied over the experiment, kg/m² |
|---|---|---|---|
| Open reference | 0 | 55 | 55 |
| Semi-closed | 150 | 59 | 46 |
| Semi-closed | 350 | 61 | 30 |
| Closed | 700 | 57 | 14 |
The highest-capacity compartment did not finish with the largest harvest. Botrytis affected its later production. With one compartment per package and different climate settings, these observations cannot isolate the effect of cooling capacity. The recorded fruit mass also does not establish commercial pack-out.
For an investor, the useful lesson is to request the whole crop record. A promising early harvest can be outweighed by later losses, rejected grades or extra operating expense. Ask when the additional saleable fruit would arrive and whether the buyer can take it then.
Keep the three quantities separate
The cooling column describes thermal service at an instant. An electricity bill measures energy consumed over time. Moving from a 150 to a 350 W/m² package adds 200 W/m² of installed thermal cooling, but it supplies no answer about annual electrical kWh. That answer needs the equipment performance and operating profile, including associated fans, pumps and heat rejection.
The CO₂ column records supplied gas. It is neither crop uptake nor avoided greenhouse-gas emissions. A lower purchased mass may have operating value, but only after comparing the delivered gas terms and the crop response under the proposed operation.
Finally, the harvest column measures fruit. Revenue requires accepted kilograms by grade and selling period. Using all harvested fruit at the best selling price would make an optimistic case even before considering cooling costs.
Build the case for the additional package
Prepare a short comparison of the lower-capacity proposal and the proposed increment. Start with the same production basis, then ask each supplier and the crop adviser to support these entries:
- Extra accepted output. Which grades and harvest periods improve, and what trial or comparable operating record supports that expectation? Keep unverified gains outside the base case.
- Additional running cost. Include electrical energy, heat-rejection service, maintenance and any utility-capacity charges. State what is included in the supplier estimate.
- CO₂ service change. Document the purchased mass and delivered cost expected under each package, using consistent crop periods.
- Installed cost difference. Include the supporting plant, controls, connections and commissioning needed to make the larger package function.
- Remaining exposure. Identify what happens to crop value during reduced cooling availability and who supports the system through the harvest season.
Compare the additional revenue after its associated crop-handling costs with the additional running costs. Only then ask whether the remaining annual benefit can support the extra capital commitment. A positive operating benefit does not establish an acceptable investment return.
Make the next decision smaller
If the larger proposal depends on an unverified yield premium, the next purchase should be evidence: a documented comparable season, a crop-specific assessment or a clearly bounded trial. If both packages already meet the production objective, require a particularly clear explanation of what the extra equipment earns.
Use the existing greenhouse energy-demand guide to keep the surrounding loads consistent, and the sawtooth ventilation guide when defining a suitable vented alternative. The investment question remains specific: what defensible additional value does the larger package deliver at this site?