68|A FONDO can be applied: Limit the light coming in through them or redirect it. To limit light you have to use curtains, blinds and other screening systems which at the end diminish the energy efficiency of the final result because all you are doing is limiting the light coming into the interior of the space. The other solution, more efficient than the previous, consists in taking advantage of the light coming through the windows and directing it and distributing it to the rest of the space. Systems of natural Light utilization There are various alternatives to distribute natural light through the windows of a space. Basically, there are two possibilities: The first one consists of utilizing the ceiling as secondary light- emitter by deflecting the light coming through the windows towards it. The other method is using light ducts, which pick-up light from outside, through collectors, and bring it to the inside through holes in the ducts that extract the light. Reflection towards the ceiling The first case is explained through an example of a lighting proposal for the classrooms of a university building. The proposal of solution calls for using and redirecting the light coming in from the windows. Obviously, leaving the windows free gives way to an exaggerated glare that would be an obstacle to the normal unfolding of activities. The solution consists in redirecting, evenly distributed, all the light that comes through the windows towards the ceiling. In this way the ceiling will act as a diffuser and will reflect all the light on the work area. By evenly distributing the light on the ceiling, contrast is significantly reduced improving the visual comfort of the users. To achieve our goal, we proposed the idea of adding reflective plates to the windows. To redirect solar light towards the ceiling, we proposed innovative blinds from the RETROLux brand. They have a very particular design that reflect the sun’s rays towards the ceiling or they send them back outside. This guarantees the visual comfort of the students. The behavior and direction of the sun rays will depend on the following parameters: Area of the louver where the ray and the clearance angle affect. To achieve the proposed goal, the use of two types of blinds was proposed: Type “U” for the bottom part of the window and type “O” for the top. These blinds can be installed in two ways: In the interior of the window or between two glass panes. The second option was chosen for the following reasons: Cleaning and maintenance: The position between two glass panes reduces contact with the environment. The interior can be accessed for cleaning. Vandalism is avoided. Safety: Having Sharp outer edges implies accidental contact with the risk that it involves. Thermal insulation: A double glass window isolates heat better. Light ducts Another alternative for the utilization of natural light is what are called light ducts. They consist of ducts that through reflection carry the light from the exterior, where a reflector is placed, to the interior of the living area devoid of natural light. Light can be carried from the rooftop of a building to the levels where natural light does not reach. At the end of the duct an “extraction” system is placed to distribute the light in the interior space. Another alternative available is placing the duct in windows and carry it towards the interior of the building. Considerations in the lighting proyect We have seen the importance of natural light in our day to day, as well as for our bodies, how much good it does to us. When doing a project, we should not limit ourselves to the requirements of the TBC. We should try to use this source of energy as much as possible and by doing it, we will accomplish better luminous environments and an improvement of energy savings in our installations. In addition, we have the technology to simulate the conditions of natural light in interior spaces. With the use of light sources of different tones and the current control systems, we can control, not only the luminous flux of the light sources but the tone of light and with it mimic in the interior the light shining outside at that very moment. This would help our bodies act in a more “natural” way and our working spaces will make us feel in a more natural environment.■ “When doing a project, we should not limit ourselves to the requirements of the TBC. We should try to use this source of energy as much as possible and by doing it, we will accomplish better luminous environments and an improvement of energy savings in our installations”. Sensor de control de luz natural. Lutron.