The search for efficient, auto-sustainable constructions allowing the user to be in contact with the outer environment, has stimulated the development of advanced strategies, in various devices, for the exploitation of the daylight. A low cost data acquisition system was developed for this study, to observe the distribution of the natural light inside a prototype and to evaluate the quantitative performance for redirecting systems. The circuit connects to a standard parallel port of any Personal Computer, and supplies 64 analog inputs, one for each luminous sensor. The luminous sensor is a resistor (Light Dependent Resistor) that responds to the illuminance with a reduction in the resistance when illuminated, it was chosen due to the spectral similarity to the human eye. As part of the circuit, a voltage divider translates the change in resistance, due to incident light into a change of voltage. After that, calibration curves are setup to relate the output voltage measured as a function of illuminance. The system is controlled through a computer using an acquisition software written in C language. It therefore provides a continuous investigation of the illuminance with a 12-bit resolution and a conversion time under 10μs.2 9951000(1996) Low-Power, 8-Channel, Serial 12-Bit ADCs, , http//www.maxim-ic(2003) CD4051B CD4052B CD4053B, , http//?www.ti.comEdmonds, R.I., Performance of laser cut light deflecting panels in daylight applications (1993) Solar Energy Material and Solar Cells, 29 (1), pp. 1-26. , February(1990) CIE 1988 2° Spectral Luminous Efficiency Function for Photopic Vision, , COMMISSION INTERNACIONAL DE LÉCLARIAGE- CIE(1994) Determination of the Spectral Responsivity of Optical Radiation Detectors, (64). , COMMISSION INTERNACIONAL DE LÉCLARIAGE- CIE, France(2004) The Newport Resource, , http//?www.newport.comSimmonds, P., (1999) Módulo de Aquisicion y Control de Datos, pp. 1-7. , Micro/Bit. V. Julio-AgostoPhilips, (2003) Integrated Circuits Data Sheet LM124/224/324/324A/SA534/ Low PowerCiampini, F., Scarazzato, P.S., Simulação e Otimização de Painéis Defletores de Luz em Campinas (2005) Proc: VII Encontro Nacional Sobre Conforto No Ambiente Construído, , Maceió