Greenhouse Systems

Whether the structure moderates the environment or holds it. A polyhouse uses natural ventilation, shade and covering to take the edges off the outside climate — the inside tracks the outside at a comfortable offset, and it costs nothing to run. A greenhouse uses active systems to hold conditions at a setpoint regardless of outside weather, and that costs power continuously. In the Indian market the words are used loosely, often by people selling the more expensive one. The question to ask is not what it is called but whether the environment is being moderated or controlled.

Most growers who ask us for a greenhouse need a well-designed polyhouse. The crops that genuinely justify controlled environment are a narrow set: high-value floriculture, specific export programmes, tissue culture, research. For tomato, capsicum, cucumber and most vegetable production, a properly designed naturally ventilated polyhouse delivers the result at a fraction of the capital and none of the running cost. We would rather sell you the right structure than the expensive one — send us the crop and the economics and we will give you an honest answer.

That is exactly the right question to ask, and it is the one most often skipped. In an active greenhouse, a power failure at 2pm in May is a crop emergency, not an inconvenience — cooling stops, internal temperature climbs fast, and you can lose a crop in hours. If your site does not have reliable power, either the specification needs generator backup, which changes the economics considerably, or you should be looking at a naturally ventilated structure that has no such failure mode. Tell us honestly about your power situation at design stage.

Film is cheaper, transmits well, and is a consumable you replace every few seasons. Polycarbonate is substantially more expensive, lasts far longer, and gives better insulation — which matters if you are heating. For most Indian applications film is the sensible choice and the replacement cost is simply budgeted. Polycarbonate makes sense for long-life research structures, for heated houses where insulation value offsets running cost, and where the labour of periodic re-filming is a problem.

Partially, and it is often good value. Adding vent automation, screening and sensors to a well-built polyhouse gets you a meaningful share of greenhouse capability without rebuilding. What you cannot retrofit is ridge height, span geometry and structural capacity — if the underlying house was badly designed, automation makes a badly designed house respond faster. Send us details of the existing structure and we will tell you what can usefully be added.