kõigi arvestatavate, paigaldusasendis olevate antud paiga valgusteid läbivast horisontaaltasandist ülespoole kiirguva valgusvoo ja nende maapinnalt peegelduva valgusvoo ning vähima mittevähendatava taeva suunas peegelduva valgusvoo summa ja maa arvestuspinna jagatis, ratio between the flux from all considered luminaires above the horizontal plane passing through the luminaires in their installed position on site plus their flux reflected by the ground and the minimal irreducible flux reflected towards the sky by the sole reference surface
