52|CUADERNOS LED technology and glare The luminance of a luminaire is a parameter that is directly related to the glare that the luminaire can produce. In interior as well as exterior projects, installation parameters that are related to the luminance of the luminaire in different directions are evaluated. This work will focus in interior instalations and the UGR (Unified Glare Rating of an installation). To analize these parameters we need to start with a photometric file, be it ldt or IES, and a software of Environmental Simulation; at this point is where we run into problems. There are productos in the market with LED technology that include diffusers, in which case we have a luminous area that is uniform, but what happens when the product is formed by LED + optic more or less together. What is its luminous area? Let us suppose we have a square downlight of LEDs + incorporated optic. We look at each emission point - Total area rectangle: 0.14 x 0.14 m2 - Led + optic diameter: 2 cm - Led luminous area + oĢptica: 0.0003 m2 If we consider as luminous area of the luminary, the luminous area equivalent to the sum of the areas of the leds +optics, on the ldt we will indicate that the luminous area of the luminaire is 0.0036 m2.. Conversly, if we consider as luminous area of the luminaire the whole area where the leds + optics are located, the luminous area to indicate would be 0.14 x 0.14 = 0.0196 m2 By doing a quick analysis of the data given by the viewer of the dialux program, where we see the results of the UGR for different standard spaces, we can appreciate that the resulst are different in every case. With just this simple analysis, we can appreciate how the UGR value changes in standard rooms simply by considering different luminous areas. The following is an example