Quick answer: In a roughly 1,000 m² calla lily greenhouse in Yunnan, China, expanding from one RYCF-22S unit to two coincided with three-point average night RH (20:00–08:00) falling from 87.4 % to 77.1 %. The share of night intervals below 80 % RH rose from 12.5 % to 67.3 %.
The greenhouse volume was about 3,000 m³; one unit operated from 1 July 2026 and two from 16 July 2026. The fan side and roadside zone stayed below 80 % for most of the night. The zone next to the evaporative cooling pad still averaged 84.6 % and is the next thing to fix. Recorded plant losses were lower in later batches, but the data shows an association only, not proof of cause.
Case at a glance
- About 1,000 m², 3 m high, calla lily, Yunnan; evaporative pad and fans.
- Two RYCF-22S floor-standing refrigerant units (rated 480 L/day at 30 °C / 80 % RH; 5,600 m³/h).
- Three-point records every 5 minutes; target: below 80 % RH at night where practicable.
The problem
July average temperature was stable at about 22.3–22.5 °C, but humidity stayed high at night. Moisture came from the crop and growing medium, from irrigation peaks, and from the evaporative cooling pad, and reduced night ventilation let it build up. With one unit running, the three points averaged:
| Point | Night RH, one unit (1–15 July) |
|---|---|
| Cooling-pad side | 93.2 % |
| Fan side | 87.3 % |
| Roadside zone | 81.7 % |
| Three-point average | 87.4 % |
What was done
- Unit 1 started on 1 July 2026; unit 2 on 16 July 2026.
- Units ran continuously at night with a controller setpoint of 60 % RH. That was an operating setting; the project target was below 80 %.
- The same three sensors were compared across the two stages.
- Yakeclimate supplied equipment and selection support; the owner's climate team coordinated the cooling pad, fans, ventilation, irrigation and controls.
Results
| Three-point average | One unit (1–15 July) | Two units (16–31 July) | Change |
|---|---|---|---|
| 24-hour RH | 85.3 % | 78.5 % | −6.8 pts |
| Night RH | 87.4 % | 77.1 % | −10.2 pts* |
| Day RH | 83.3 % | 79.9 % | −3.4 pts |
| Night intervals below 80 % | 12.5 % | 67.3 % | +54.8 pts |
*As reported by the project analysis from unrounded values.
| Point | Night RH, one unit → two units | Night intervals below 80 % |
|---|---|---|
| Cooling-pad side | 93.2 % → 84.6 % | 0 % → 27.3 % |
| Fan side | 87.3 % → 75.1 % | 0.6 % → 80.5 % |
| Roadside zone | 81.7 % → 71.8 % | 36.9 % → 94.1 % |
Humidity rebounded briefly around 20 July; site notes say "possibly after irrigation" and "rainy day / after irrigation". The records don't separate the two effects.
Plant losses: association only
| Batch | Dehumidification coverage | Recorded plant loss |
|---|---|---|
| 6 | None earlier, one unit added later | 22.40 % |
| 7 | One-unit transition | 12.88 % |
| 8 | Gradual expansion to two units | 8.76 % |
Losses fell as coverage increased. But planting dates, weather, irrigation, disease pressure and management also differed, and loss counts lag conditions by about 5–7 days. The data doesn't show that dehumidification caused the whole reduction, and it doesn't predict the same result elsewhere.
Four engineering lessons
- Measure at several points. A three-point average below 80 % didn't mean every zone was below 80 %; the pad side stayed humid.
- A setpoint is not a result. A 60 % controller setting doesn't mean the house reached 60 %.
- Rated capacity needs its test condition. At about 22 °C, field capacity is lower than at the 30 °C / 80 % rating, so the result can't be calculated as rating × number of units.
- Trends beat spot readings. The staged comparison showed both the improvement and the zone still at risk.
Next steps on this site
- Reduce moisture from the cooling pad when temperature allows, and let the pad dry after shutdown.
- Extend operation in rain, after irrigation and during humid nights; log the changes.
- Keep monitoring the pad-side point and plant losses in later batches, in the same time windows.
We recommend reducing cooling-pad moisture when temperature allows and tracking the pad-side night RH at this site, where the two-unit stage still averaged 84.6 % RH.
Applying this to another greenhouse
These results are for this greenhouse, crop and July 2026 conditions; they are not a guarantee elsewhere. For a project review, see the project design data, how many dehumidifiers and our greenhouse dehumidifiers.
FAQ
Frequently asked questions
How much did night humidity fall with two dehumidifiers?
The three-point night average fell from 87.4 % to 77.1 % RH.
Why was one area still humid?
The zone next to the evaporative cooling pad received moisture from the pad; it averaged 84.6 % at night with two units.
Did dehumidification reduce plant losses?
Losses were lower in later batches, but other factors changed too; the data shows an association, not a proven cause.
Data notes
- Records: three points, 5-minute intervals, July 2026; night = 20:00–08:00.
- Rated parameters are from the product datasheet; delivered-unit parameters should be checked against the nameplate.
- Sensor coordinates and airflow direction were not recorded in the available material.
