14|AULA cd Sistema uniforme integrado. Museo de Arte Contemporáneo de Nueva York. Sanaa. One of the main purposes of lighting systems is to ensure that the lighting effects reflect the conceptual ideas defined in the project. In this regard, the relationship between lighting systems and space is fundamental and is part of the basic know-how of architectonical composition. This relationship must take into account the lighting effects as such, as well as the aspects that compose the lighting system itself, considering it as a formal element in space. Most of the actual approaches used in the choice of a lighting system focus on responding to the functional requirements or questions of energy efficiency which may arise. Our approach mainly deals with the aesthetical and compositional considerations which have led us to establish a new classification of lighting systems. This is a comprehensible and easily useable classification for architects and light designers at the project stage. Key words. Lighting, lighting systems, light design, Architectural lighting 1. Background. At present the lighting sector in architecture presents a clear division between two types of products: the ones addressed to a type of lighting called “architectonical”, characterized by products in which the technical and qualitative design of light effects predominate. It includes built-in implementations that can be embedded or attached to structures; and the so-called “decorative” illumination products, in which the formal design of the object predominates, it includes superimposed implementations that are also attached or hanging from the structures. Occasionally this division of products is complicated and ambiguous. The “decorative” products usually have a singular appearance (presenting a few elements), whereas the “architectonical” ones are generally put in place (presenting a big number of units) on a repetitive basis. The CIE International Commission on Illumination classifies lighting systems according to the way light is distributed in an establishment, as follows: General, Localized general, and Local. It also classifies luminaries, according to the way the luminous flux is distributed in space, as follows: Direct, Semi-direct, General diffuse, Semi-indirect, and Indirect. We can observe that in the description of their characteristics it uses terms that correspond both to luminaries and to lighting systems indiscriminately. Other authors, like Silvio Di Ponte, propose a kind of lighting