Calculator Inputs
Example Data Table
| Scenario | Baseline PPFD | Before | After | Canopy | Hours | Area | Est. PPFD gain | Est. DLI gain |
|---|---|---|---|---|---|---|---|---|
| Leafy greens bench | 450 µmol/m²/s | 25% | 70% | 0.50 | 12.0 | 4.0 m² | 16.20% | 16.20% |
| Tomato row edges | 650 µmol/m²/s | 30% | 75% | 0.55 | 12.0 | 6.0 m² | 17.25% | 17.25% |
| Shade-prone corner | 500 µmol/m²/s | 20% | 80% | 0.40 | 10.0 | 3.0 m² | 10.80% | 10.80% |
Examples are illustrative. Adjust canopy, shading, and loss to match your layout.
Formula Used
1) Reflectivity change
ΔR = max(0, Rafter − Rbefore)
2) Added canopy light (PPFD)
AddedPPFD = BaselinePPFD × (ΔR/100) × CanopyFactor × ShadingFactor × (1 − LossFactor)
3) New canopy light
NewPPFD = BaselinePPFD + AddedPPFD
4) Daily Light Integral (DLI)
DLI (mol/m²/day) = PPFD (µmol/m²/s) × Hours × 3600 ÷ 1,000,000
5) Total extra light over your area
ExtraMol/day = (NewDLI − BaselineDLI) × Area
How to Use This Calculator
- Measure or estimate baseline PPFD at the plant canopy.
- Enter your current and upgraded reflectivity percentages.
- Set canopy capture based on geometry and plant density.
- Adjust shading and loss to reflect real installation conditions.
- Click Calculate to view PPFD and DLI gains above.
- Download CSV or PDF to save results for comparisons.
What Reflectivity Changes
Reflective films, white mulches, and bright ground covers redirect photosynthetically active radiation toward leaves that would otherwise stay shaded. Clean silver films may exceed 80–90% reflectance, while bare soil can sit near 10–20%. The calculator focuses on the upgrade gap (after minus before) so you can compare materials on a consistent baseline.
Inputs That Matter Most
Baseline PPFD is the canopy light level before any reflective upgrade, measured in µmol/m²/s. A larger baseline means the same reflectivity increase produces a larger absolute gain. Canopy capture (0–1) represents how well the crop architecture receives reflected light; dense canopies often range 0.35–0.65. Shading factor accounts for obstructions, while loss factor models dirt, wrinkles, and distance that can cut performance by 5–40%. Photoperiod should reflect effective high-intensity hours; in winter it may be 8–10 hours, while supplemental lighting can extend it to 14–18. When comparing setups, keep photoperiod constant to isolate the reflectivity effect across your seasons.
Interpreting PPFD And DLI
Added PPFD shows instantaneous improvement at the canopy. Daily Light Integral converts that improvement into a daily total: DLI = PPFD × hours × 3600 ÷ 1,000,000, reported as mol/m²/day. For example, a 40 µmol/m²/s gain over 12 hours adds about 1.728 mol/m²/day. Use the area input to scale that added DLI into total extra mol per day across beds or benches.
Practical Installation Checks
Place reflective surfaces where they “see” the canopy, not just the aisle. Keep films taut and clean; dust can drop reflectivity quickly. Avoid creating hotspots by leaving ventilation and monitoring leaf temperature. Where glare is a safety risk, angle surfaces down and keep reflective edges away from eye level.
Tracking Results Over Time
Re-check PPFD with the same sensor position and time window after installation, then update the baseline if your lighting changes seasonally. If gains are lower than predicted, reduce canopy capture or increase loss to match reality. Save CSV or PDF snapshots so you can compare different materials, cleaning routines, and layouts.
FAQs
How do I estimate reflectivity percentages?
Use manufacturer specs as a starting point, then adjust downward for dust, aging, or discoloration. White paint and clean films often rate 70–90%, while soil and dark fabric can be under 20%.
What is canopy capture factor?
It represents the share of reflected light that reaches productive leaves. Open canopies and well-placed side reflectors can reach 0.6+, while dense foliage or poor angles may be 0.3 or lower.
Why include shading and loss factors?
Shading accounts for structures or plants blocking reflection. Loss accounts for dirt, wrinkles, distance, and non-ideal angles that reduce effective reflectance. Together they help the estimate match real installations.
Can reflectivity improvements overheat plants?
Yes. Extra light can increase leaf temperature, especially in still air. Monitor canopy temperature during hot days, keep airflow strong, and avoid placing highly reflective surfaces where they concentrate light onto a small spot.
What PPFD baseline should I use?
Use a measurement at canopy height under typical conditions for your comparison period. For sun, measure around the same time each day; for lamps, use the normal operating setting and mounting height.
How can I validate the calculator results?
Record PPFD before and after at several points, then average the readings. If measured gains are lower, increase loss or reduce capture in the inputs. Save reports to track improvements after cleaning or repositioning.