Faculty Publications
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Item Effect of Solar Optical Properties of Building Envelope on Time Lag, Decrement Factor and Energy Saving of Buildings(Springer Nature, 2020) Mahapatra, D.; Ashok Babu, T.P.A.World has been suffering from energy crisis since 1970. This is because of the increased population and industrialization. Buildings have a significant contribution to total energy consumption across the globe. The increased urbanization leads to boom in construction of buildings. The materials used for the construction of buildings affect the climate of the city up to a great extent and affect the energy consumption as well. So, construction materials should be chosen wisely. The surface temperature of the building envelope is affected by the coatings used. Cool coatings help in reducing the surface temperature of the building envelope. Time lag and decrement factor are the indicators of energy saving in building. In this paper, the effect of cool coating on time lag and decrement factor was studied. Values of time lag and decrement factor were evaluated in different climatic zones of India. It has been found that as the absorptivity of the building envelope increases, the decrement factor increases. By changing the absorptivity from 0.2 to 0.73, a minimum change of 16% (New Delhi) in decrement factor and 11.75% (Jodhpur) in surface temperature was observed. The maximum change in decrement factor was 56.44% (Jodhpur). The maximum change in surface temperature was 39.02% (Bangalore). So, it should always be practised to keep the absorptivity of the building envelope as low as possible. © 2020, Springer Nature Singapore Pte Ltd.Item Optimizing Vertical Air Gap Location Inside the Wall for Energy Efficient Building Enclosure Design Based on Unsteady Heat Transfer Characteristics(Springer, 2020) Saboor, S.; Nagaraju, S.; Rizvan, S.M.; Gorantla, K.K.The chief principle of this paper is to optimize the location of vertical air space within composite walls based on thermal unsteady response state parameters that include admittance, transmittance, attenuation factor, and time lag. For computation of these parameters, a MATLAB code has been generated. This code solves 1-D heat flow diffusion equation with convective periodic boundary conditions. Six building construction materials such as laterite stone, burnt brick, mudbrick, reinforced brick, fly ash brick, and concrete block were selected and computations were made for 42 configurations of the composite walls. From this, it is concluded that composite walls with air space located at the outer side of the external wall and the mid-center of the external wall are energy efficient from higher time lag, higher thermal admittance, and lower thermal transmittance perspective and the composite walls with air space located at outer and inner sides of the external walls are the best from the lower decrement factor perspective, among seven studied configurations. The results of the study reduce the air conditioning loads in buildings. © 2020, Springer Nature Singapore Pte Ltd.Item Variation of Time Lag, Decrement Factor and Inside Surface Temperature with Solar Optical Properties of Building Envelope in Different Climatic Zones of India(Springer, 2020) Mahapatra, D.; Ashok Babu, T.P.Maintenance of thermal comfort inside buildings requires a significant amount of energy. According to the Centre for Science and Environment, the energy spent on achieving thermal comfort in commercial buildings and in residential buildings are 31% and 7%, respectively. Considering the energy crisis that world has been suffering; every individual should try to save energy by some means. The increase in urbanization over the last few years gave rise to boom in constructions. Choosing the materials used for the construction of buildings wisely can contribute towards energy saving. The solar optical properties of building envelope affect the surface temperature up to a great extent which in turn affects the energy used for thermal comfort. In this paper, the effect of solar optical properties on time lag decrement factor and inside surface temperature is studied in different Indian climatic zones. © 2020, Springer Nature Singapore Pte Ltd.Item Influence of ambient air relative humidity and temperature on thermal properties and unsteady thermal response characteristics of laterite wall houses(Elsevier Ltd, 2016) Saboor, S.; Ashok Babu, A.B.P.S.This paper presents the experimental investigation of the effect of ambient air humidity and temperature on thermal properties of the laterite rocks used in South-West coastal India. The experimental technique employed was transient plane source method in the saturated salt solution humidity controlled chamber. Experimental results showed an increase of thermal conductivity by 14.7% and specific heat by 9.15% with an increase in the relative humidity of ambient air in the hygroscopic range. A porous and ferruginous matrix of laterite was studied using a scanning electron microscope. The effects of relative humidity of the ambient air and temperature on the unsteady state thermal heat transfer characteristics such as transmittance, admittance, decrement factor, time lag, surface factor, surface factor time lag and heat capacity for different thicknesses of the laterite rock walls were investigated analytically. One dimensional heat flow equation under periodic convective boundary conditions was solved using matrix algebra and a computer simulation program which employs a cyclic admittance method was developed using MATLAB to compute unsteady state thermal characteristics. Results indicate that the decrement factor reduces by 8.35% and time lag increases by 2.88% with an increase in the relative humidity of ambient air compared to the dry state for the Indian standard laterite rock thickness. © 2016 Elsevier Ltd.