Plan inflation air needs for garden tunnels fast. Compare metric and imperial results instantly here. Choose a blower size, avoid sagging film problems today.
Size the inflation airflow needed to keep two film layers separated. The model uses gap volume, air changes, leakage, and a safety factor.
| Scenario | Area | Gap | ACH | Leak | Safety | Design airflow |
|---|---|---|---|---|---|---|
| Small tunnel | 120 m² | 60 mm | 4 | 20% | 10% | ~38 m³/h (≈22 CFM) |
| Medium house | 300 m² | 75 mm | 5 | 30% | 15% | ~129 m³/h (≈76 CFM) |
| Large house | 900 m² | 80 mm | 6 | 35% | 20% | ~622 m³/h (≈366 CFM) |
Examples are illustrative. Use measured area and local conditions for planning.
This calculator sizes airflow for stable inflation. Select a fan by matching its curve to your target airflow at the needed pressure.
Double layer film creates an insulating air space that reduces convective heat loss and limits cold drafts around crops. A stable, evenly inflated gap also prevents the two skins from rubbing, which can shorten film life. This calculator helps estimate the airflow required to keep that gap consistent during typical operating conditions.
Gap thickness influences both insulation and the volume of air you must move. A wider gap improves thermal performance up to a point, but it raises the gap volume and can increase blower demand. Many growers target 40–100 mm for tunnels and houses. Use measured frame geometry rather than nominal bay size for better planning.
Air changes per hour represent how often the gap air is refreshed to maintain firmness and respond to wind loads. Leakage accounts for seams, end walls, vent penetrations, and clip lines. Tight installations can use lower leakage, while older or frequently vented houses need higher allowances. A safety factor adds extra margin for seasonal wear and small tears.
Inflation pressure is commonly expressed in pascals or inches of water column. Higher setpoints can improve rigidity, but only if the structure and fasteners can handle the uplift and vibration. Select a blower that can deliver the design airflow at the target pressure, considering intake screens, ducting, and backdraft dampers. Fan curves are essential for final selection.
Use the design airflow to size equipment and to set maintenance expectations. If your greenhouse shows sagging film, raise leakage or safety values and inspect end seals, inflation tubing, and clamps. If the calculated power seems high, confirm units and verify that the gap thickness reflects actual spacing. Saving results as CSV or PDF supports purchasing and seasonal checklists. For automated systems, pair the blower with a pressure switch or controller so airflow ramps smoothly, avoiding overinflation and film flutter during storms at night.
Enter the total film coverage area for the inflated cavity, not the floor area. Include roof and sidewall surfaces that form the double layer.
Start with 3–6 ACH for most installations. Use higher values for windy sites, loose fastening, or frequent venting that disturbs the inflated gap.
It represents air escaping through seams, clips, end walls, and openings. New, well sealed films may need 10–25%, while older or patched films may need 30–60% or more.
Suppliers may rate blowers in either pascals or inches of water column. The calculator converts between them so you can compare fan specs consistently.
No. It is a planning estimate based on pressure, airflow, and efficiency. Real power depends on fan curves, duct losses, screens, dampers, and local electrical supply.
Check end seals, inflation tubing, and clamp lines for leaks. Increase the setpoint cautiously, and confirm the blower can deliver the design airflow at pressure.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.