60|A FONDO W hen I mention efficiency, I am not thinking only about the lumens per watts that they can provide. There are light sources capable of offering more than 150 lm/W, in white light and with a good chromatic solution. Furthermore, the optical systems that go with these light sources, and that deliver light output to the spaces where it is needed, contribute greatly to the final overall efficiency. We must not forget the auxiliary equipment, responsible for controlling the operation of the light source. They can regulate, almost instantly the operating conditions of the light source. All of the above makes the potential for savings in the “old fashioned” lighting installations very high. Many times, when approaching the solution to a project and doing the calculations, be it in new projects or in the intervention of existing projects, we “forget” natural light. It is a fact that the Technical Building Code (TBC), in the HE-3 document: Energy efficiency in lighting, lays down the criteria for maximizing the energy efficiency of our installations. It is done by establishing basic guidelines: On the one hand, it establishes the limit of the Energy efficiency rating of lighting (EERL). This parameter indicates how many Watts per square meter are necessary to obtain 100 lux on the work plane. The TBC sets up the limit values of this parameter, on the basis of the importance of the space to be illuminated and of the activities performed in them. It also limits the potency of the set formed by the lamp and the auxiliary equipment. There are drivers and auxiliary equipment that can use up to 25% of the normal potency of a lamp; this implies an increase of the electricity consumption without improvement in the benefits. The TBC also requires a maintenance plan for the project in order to guarantee the level of service of the installation through its entire life-cycle. By calculating, it would be easy to prove that the operating costs (energy, maintenance and replacement) are much higher than the installation costs. Thus, the importance of selecting efficient and durable components; it will reflect in the operating costs. Finally, another requirement of the TBC has to do with the amount of natural light provided. It establishes a set of measures designed to regulate the flow of light coming in from the light sources, based on size and position of windows, orientation of the building and any other obstacle that could block the flow of natural light. Energy consumption is minimized through the use of sensors that detect presence and movement, light sensors, schedules, etc., without reducing the lighting performance of the installation. These are the guidelines set by the TBC-HE3 to maximize the energy Robert Ramos/Fundació Privada Hospital de Sant Pau