Bay-by-bay climate sensors and curtain controls retrofitted to old polyhouses
TL;DR Fogline fits wireless temperature and humidity sensors into each bay of an existing naturally ventilated polyhouse and wires them to the side curtains and foggers. Growers of capsicum, cucumber and cut flowers pay a fitting fee and a monthly plan, because one hot afternoon with the curtains down can cost a season's quality.
Most Indian polyhouses are naturally ventilated - plastic over a steel frame, with roll-up side curtains and sometimes foggers, all worked by hand. Inside, heat builds fast.
A 2026 field study in naturally ventilated polyhouses found that about 48% of 154 worker observations fell outside the acceptable thermal range[1]. If the workers are uncomfortable then the crop is under stress too.
Research centres are trying automation. CSIR-CMERI's Ludhiana centre opened a naturally ventilated polyhouse and began a retractable-roof version run by PLC software in 2021[2]. And on ordinary farms? The controls are still a person deciding when to roll the curtains up.
Fogline is a retrofit kit, not a new greenhouse, so the grower keeps the existing structure. The kit is one battery sensor node per bay for air temperature and humidity, a leaf-wetness probe in the worst corner, and motor kits on the side curtains, plus relays on the foggers and drip pump.
A small controller runs simple rules - open the curtains when a bay crosses a set temperature, start the foggers when humidity drops, and close everything before forecast rain or wind. The grower sees each bay on a phone and gets an alert when a rule fails, like a curtain that didn't move.
The seed promised predictive, plant-level control, and I reframed it. Sensing every plant doesn't pay back on a one-acre polyhouse growing a ₹30–80 crop. Bay-level readings catch the hot and humid pockets that matter, and simple rules a grower can read are far easier to trust than a black box.
The user and the payer are the same person, a polyhouse owner, often with 0.5–2 acres under cover, growing for city markets or exporters. Some buy through FPOs or input dealers.
Global climate-control systems are built for large glasshouses[3], and Indian net-house makers sell the structure itself[4]. Nobody publishes a price for a retrofit controller in India, so the sprint has to find what growers will pay.
Low-power radio modules and sensors are cheap, and approval for Wi-Fi, Bluetooth and Zigbee devices in India is a self-declaration at ₹10,000 per model[5]. Indian researchers are now publishing on polyhouse heat and climate covers[1][6], which gives growers and lenders a vocabulary for the problem.
I found no public figure for polyhouse automation retrofits in India. The narrower signal is buyer behaviour - one net-house maker packages agronomy support and claims its net houses run 3–5°C cooler inside[4], which shows growers pay for temperature control bundled with advice.
Your market is the installed base of older polyhouses. Count it district by district during validation.
A Dutch firm sells climate computers, sensors and a crop platform to high-tech glasshouses[3]. An Indian startup sells modular net houses of 240–1,600 m² with a year of agronomy advice[4], but not controls for an existing polyhouse. CSIR-CMERI has shown PLC-run roofs in research[2].
The gap is a cheap, fit-in-a-day kit for the thousands of manual polyhouses already built.
| Difficulty | Moderate (42/100) |
| Starting capital | ₹60 L–1.1 Cr |
| Time to launch | 6–9 months |
The electronics are simple. Curtain motors have to survive dust, fogger mist and power cuts, and installs have to take a day and not a week. The harder part is service, because a dead sensor during a heatwave kills trust and so you need technicians within a few hours of each cluster.
The kit needs no sector licence, as far as I found, but the radio and power parts do.
Building this outside India? The categories above usually have a local equivalent, so check with your own regulator.
Keep the core control rules simple and readable. Don't let a model you can't explain run the curtains on its own during a heatwave.
Want to work out the AI layer for Fogline? Talk to Yash →
Here's what can go south -
I like this for a founder with farm electronics or irrigation-dealer experience who can build a service network cluster by cluster. If you're expecting software margins then it's a poor fit.
First prove one thing - in five polyhouses over one hot month, the kit keeps peak bay temperatures measurably lower than manual control.
Plan for roughly ₹60 L–1.1 Cr, covering sensor and motor kits, installation teams and a service network near your clusters.
No sector licence, as far as I found. Wireless parts need WPC type approval and some power adaptors need BIS registration.
Yes, the retrofit idea works anywhere growers run manual, naturally ventilated polyhouses. Check local radio and electrical rules before shipping.
The free Fogline validation kit has the line-by-line capital breakdown, the effort scoring, the radio and data checklist, a 14-day validation sprint with pass/fail targets, a 90-day launch plan, 10 interview questions for growers and dealers, and 5 assumptions to test. Download the kit →
Thinking about building Fogline or something close to it? The make-or-break work is keeping motors and sensors alive in wet, dusty polyhouses with fast repairs, and that's the part I'd want to plan with you first. If you need a hand, you know where to find me. Talk to Yash →
For illustration only. Names are fictional and ideas hypothetical; sourced facts are real but may be out of date. Nothing here is legal, financial or professional advice, and Yash Khatri is not personally liable for any use of it. Read the full disclaimer.