Average PPFD can only be calculated accurately using mathematical equations based upon photometric readings for the lamp from integrated spheres and goniophotometers.
Average PPFD should be calculated using what has become industry standard software AGI32, us and several other leading horticultural led companies have adopted the use of this software and it has become industry standard due to its market leading features for horticulture.
A 25% grid should be used for measurements as this allows understanding of the scale for both small and large growers.
Average PPFD measurement planes should be 100% transparent so that we are measuring PPFD hitting a point with no reflective interaction from the bottom surface as this increases the result exponentially an it differs for different light sources and lamp types.
It is not possible to accurately simulate a plants absorption with a measurement plane as there are many different types of plants whose canopy properties change at different points in their life cycle.
- Lower floor surface should be dark green no greater than 48%.
- Indoor wall surfaces should be no greater than 90% light grey reflectivity to allow for ageing of surfaces.
- Measurement planes should be 100% transparent