The Natural Light and the Daylight Factor in a Non-Residential Building - Case Study of the Classroom of an Educational Center

Light, or its absence, represents a substantial issue in architecture. Its presence is essential to define the space; natural light in particular, "soft" and continuous, has this task. Natural light design aims to minimize the energy consumption of buildings and maximize well-being in confined spaces. It is an element of improvement of comfort conditions. The variability of natural light during the day is a positive stimulus both from the biological and psychological point of view for the human being and work environments lit by natural light are considered much less stressful for the eyes. In addition to that, when a workplace is exposed to natural light it makes it more productive, more efficient, healthier and more creative. Furthermore, a proper design of the building should guarantee, at least during the hot seasons, the correct implementation of natural light, in such a way to reduce the energy intake of artificial lighting. The present study is designed to analyze natural lighting in a classroom of the Environmental Education Building of Pozuelo de Alarcón (CREAS). This building was chosen due to the commitment that the Municipality of Pozuelo has with the environment and the leading design in terms of sustainability and energy efficiency. After an overview of the current state of art and the theoretical principles, the experimental work began with the precedent monitoring campaign included between February 24 and March 6, 2017. Ten luxmeters, connected to OPUS 200 and 08, were first strategically located inside the classroom, in accordance with standard EN ISO / IEC 17025: 2017 and EN 12464-1: 2012; they were set up to do a continuous data recording. The results is classified according to three scenarios: 1) days with clear skies; 2) days with intermediate skies; 3) days with overcast skies. For these three possible situations, the Daylight Factor (DF) was calculated, for each luxmeters, for 3 different hours, 9 AM, 12 AM and 16 PM. This new database with the use of Surfer, an interpolation software, has allowed us to know the lighting horizontal distribution on the working plane of the classroom. I do the s ame with the experimental data obtained from the Velux Light Simulation program, with the same conditions of experimental modeling. In fact, thanks the simulation of the environment, we obtain the distribution of lighting in the classroom work plane. The next step was the main one, the modeling of the workshop room on DesignBuilder, software that is capable of developing the analysis of natural lighting based on the Radiance software. From here, we have exported and studied the values of Daylight Factor (DF). With the collected data, a validation of the DesignBuilder program was possible with the comparison with the data of the site and those obtained with Velux. The results show a consistency between experimental and simulation values. This work shows that areas with wide windows, such as the classroom under study, present heterogeneous lighting and the great deal of light can cause both thermal and light discomfort. At this point, it was necessary to check the performance of the incorporation of different passive designs to obtain a more homogeneous DF, by guaranteeing lighting comfort for users. So the redesigned classroom’s behavior was analyzed.