Modelling and measurements of illuminance for diverse atmospheric conditions in the northeast of Brazil / Medidas e modelagem da iluminÃncia para diversas condiÃÃes de cÃu no Nordeste do Brasil

AUTOR(ES)

SÃrgio da Silva Leal

DATA DE PUBLICAÇÃO

2006

RESUMO

In Brazil, and particularly in the Northeast region, illuminance measurements are not a part of the routine measurements in meteorological stations. Therefore, the availability of information on illuminance is rarer than the measurements carried out on solar irradiation. In this context, two stations for measuring illuminance and solar irradiation were installed in Pernambuco: one in Recife (tropical maritime climate), in April, 2003, and the other in Pesqueira (semiarid), in September, 2004, with the aim of carrying out simultaneous measurements of daily solar irradiation and illuminance, in such a way as to permit the modeling and statistic validation of the relationship between these two parameters and to make possible the estimation of the illuminance where up to now there only exist information on solar irradiation. An evaluation of the solar irradiation registry and illuminance measurements confirmed the large potential of the utilization of natural illuminance in Pernambuco. The illuminance values are high enough to supply, on their own, the daily illumination necessity of a commercial office during 80% of the annual working hours (8 a.m. to 5 p.m. oâclock). A comparison between the luminous efficiency models shows that the Perez local and Alados models are the best for localities in Recife and Pesqueira, which produce, respectively, mean quadratic deviations of 10% and 3% and a bias in the order of the 3% and 1%. Additionally, it must be considered that these estimations are inside experimental error since the illuminance and solar irradiation sensors that were used have a maximum calibration error of 5% and maximum annual drift of 2% and, therefore, the experimental measurements of luminous efficiency would have an associated error in the order of 10% to 12%, after a year of measuring

ASSUNTO(S)

iluminÃncia modelling and measurements luminous efficiency modelagem e medidas engenharia nuclear eficiÃncia luminosa illuminance

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