The luminous flux is the amount of light generated from a luminaire. This value is only relatively representing the performance of a product, as it is up to the optics to use this light in an efficient way.
Distributing the lumens (light) only where needed provides extra energy savings. We strictly declares the lumens of broadly available products, not theoretical values as many competitors do.
The overall uniformity is calculated from the ratio between minimum luminance [Lmin] and average luminance [Lav], measured in all the points of the matrix drawn in the norm.
The illuminance is the quantity of light hitting a specific surface, like a road or a warehouse floor. Illuminance is the measuring parameter to consider for sidewalks, pedestrian crossings, roundabouts and all the industrial lighting.
The transversal uniformity is the worst ratio between Lmin and Lmax between all transversal lines perpendicular to the centerline. This value applies only for tunnel lighting calculations.
The luminance is the quantity of light that the observer’s eyes (usually a driver) see, reflected from an area of 1m2 of the road surface seen from distance. It is the measuring parameter for streetlighting and tunnell lighting, as it represents a model of the real world driving conditions, where obstacles must be identified in time to permit a reaction.
Longitudinal uniformity is calculated from the ratio between minimum luminance [Lmin] and maximum luminance [Lmax], measured on the axis of the lane. The measurement is repeated for every lane. It’s a primary importance value in street and tunnel lighting design. An uniformity level below the minimum requirement is clearly visible when dark and bright stripes are evident on the pavement.
The TI index measures the debilitating glare, caused from the presence of light sources in the sight of an observer. The percent value measures the increment of luminance that should be applied to the road to compensate the presence of the said light source, keeping the same visibility of obstacles. TI applies only for street and tunnel lighting.
The UGR is a grid of values used to classify the glare produced from luminaires in indoor environments. It’s not a number that can be assigned to a luminaire but it can be obtained only running a lighting simulation of the room, defining an observer point (like a workstation) and including in the calculation parameters such as the light emitting surfaces and the surrounding illuminance.