52|CUADERNOS Prismatic natural lighting systems The natural lighting systems market for one story public buildings is based in products that do not diffuse light. If they do, it is at a reduced and erratic level, without projection in any given area or glare at the midday hours. A prismatic natural lighting system improves this situation. Skylights and dormer windows of diverse materials are used profusely without fully utilizing their light inasmuch as conventional electric lighting cannot be shut off. They just become a source of heat and distorted light, with little light at the early and late hours of the day or even in the midday hours, during the summer months. Granted, there are other products that do diffuse light: light tubes, skylights with nanomaterial filters, systems of transmission by optic fiber but they are costly and the savings they generate do not offset the initial investment. In the context of rising prices for energy, the expenses of illuminating a logistics warehouse, an industry, and a mall are skyrocketing. Many of these centers have installed solar photovoltaic panels to capitalize on their roofs, blocking light even more. Something paradoxical. In the roofs of these buildings, the most economical skylights are installed fully aware that the light they give is not sufficient; the least expensive prevails. After two or three years, these skylights are dirty and deteriorated allowing only the heat to come through. LledoĢ lighting has developed LledoSunoptics, a simple solution using complex technology that offers capture and diffusion in one system. On top of everything, it offers savings of more than 30 per cent by less use of conventional lighting and a return of the investment on the installation in three to five years. Even though this system is novel it has been in use in the USA for more than 20 years. The principal hypermarket of the USA, Walmart, has been using Sunoptics for years in all their stores. The energy efficiency market looks for savings conditioned by low investments. This is the only way efficiency makes sense. Substituting conventional lighting or introducing LEDS generates big savings but the investment is high. Photovoltaics with Premium obtains paybacks of ten years. The option