Beating Monsoon Humidity: Practical Ventilation & Dehumidification Strategies for Tropical Greenhouses
Beating Monsoon Humidity: Practical Ventilation & Dehumidification Strategies for Tropical Greenhouses
Spend a single wet season in Malaysia or Luzon and you learn fast: humidity isn’t a number, it’s a threat.
Night readings hover above 90 %, afternoon storms dump heat‑laden air into the house, and Botrytis shows up before you can say “fungicide rotation.”
The conventional fix is brute‑force ventilation—fans on full, pads soaking, power bills soaring. On the other hand, Autogrow’s MultiGrow controller takes a subtler, data‑driven route: anticipate the spike, act early, and never waste a watt you don’t have to.
1. Know the Enemy Before It Condenses
The foundation is live sensing.
MultiGrow pulls outside humidity, temperature, and wind speed from a local weather station, then matches that to internal VPD (vapour‑pressure deficit) and leaf‑wetness readings.
If the external air is cooler but nearly saturated, the system won’t “invite” it inside. Instead, it ramps circulation fans to strip water off leaf surfaces and lets heaters nudge the canopy just one or two degrees, enough to push RH below that Botrytis danger zone without cooking the crop or emptying the diesel tank.
2. Fan‑and‑Pad Optimisation (Spoiler: It’s About Sequencing)
Most growers treat pad drainage pumps and exhaust fans as a married couple: on and off together. MultiGrow lets you sequence them. When thunderstorms roll in, you can:
Pre‑purge with high‑velocity exhaust while pads stay dry—dumping trapped heat before the wet wall builds a fog bank.
Pulse the pad in 2‑ to 3‑minute bursts as long as outside RH sits below 85 %. The moment the storm pushes that number higher, the pad pump idles and circulation fans take over.
Return to cooling only after external RH drops again, verified by the weather sensor rather than guesswork.
3. Fogger Dos and Don’ts
High‑pressure fog cools crops quickly but can tip the house past saturation if you aren’t tallying leaf‑temperature lift. MultiGrow’s sunlight‑weighted algorithm measures incoming PAR; if clouds drop radiation 30 % in under five minutes, the controller automatically reduces fog duration.
The logic is simple: fewer photons, lower transpiration, less fog required.
4. Emergency “Dry‑Down” Routine
When RH still creeps past 90 %—usually at 2 a.m.—MultiGrow executes a dry‑down: heaters fire briefly, roof vents crack 5 %, and circulation fans speed‑cycle for 20 minutes.
Because each action is small and staggered, the canopy wakes drier but not stress‑stretched. Many growers used to run space heaters wide‑open for hours; replacing that with a two‑stage dry‑down cut overnight energy bills.
5. Maintenance Beats Magic
Even the best algorithm fails if sensors are blind.
Clean humidity probes monthly; bird droppings on the rain plate trick the system into “thinking” every night is dry. MultiGrow’s dashboard flags any sensor that deviates from an average—your cue to grab a cloth before the next downpour hits.