Study of Various Glass Materials to Provide Adequate Day Lighting in Office Buildings of Warm and Humid Climatic Zone in India

Abstract

A huge amount of energy is attributed to cooling, heating and day lighting in buildings. In the air conditioned space the windows have been closed and the sun control is used to reduce the radiation load. This results in low lumens of light in air conditioned space and demands the artificial lighting and increases the energy consumption for lighting and also the air conditioning load. The objective of this work is to allow the natural sun light through the glass window of same area, and thus less lighting load in the air conditioned space for different climatic conditions. To achieve the objective of the work an investigation of spectral properties of different glass materials such as bronze, green, grey, bronze-reflective, green-reflective and grey-reflective glasses is carried out experimentally using Perkin Elmer lambda 950 Spectrophotometer in the visible solar spectrum region of wavelength range from 380nm-780 nm, to provide optimum daylight factor as per SP: 41 1987 Indian standards to office buildings. The measured spectral properties were used to compute the visible solar properties in the visible region by using British standard method with a MATLAB code. The computed properties transmittance, reflectance and absorbance are used in the simulation tool for daylight calculations. The laterite building models with various window glazing materials were designed in Design builder 4.3.0.039 version tool and day lighting simulation was carried out in Energy plus 8.1.0.009 simulation tool for warm and humid climatic region of India. In this work, total twenty four building models with six window glass materials were investigated in four orientations of window such as East, West, North and South. The simulations were carried out in both summer and winter climates of warm and humid climatic zone for an office building. As far as the daylight factor is concerned, the green-reflective glass placed in south orientation is the best due to its adequate daylight factor (2.05% to 2.06%) in summer season and bronze glass window placed in north orientation is observed to be the best due to its sufficient daylight factor (2.2% to 2.8%) in winter among six studied window glass materials to Mangalore location (Latitude 12.87 N). The results of the study help in designing natural daylight buildings which in turn reduce energy consumption. � 2017 The Authors.