Faculty Publications
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Item Effect of Air Space Thickness within the External Walls on the Dynamic Thermal Behaviour of Building Envelopes for Energy Efficient Building Construction(Elsevier Ltd, 2015) Saboor, S.; Ashok Babu, A.B.T.This paper presents the comprehensive investigation of the effect divided air space thickness within the wall on unsteady heat transfer characteristics such as thermal transmittance, thermal admittance, decrement factor and time lag of five building material walls for energy efficient building enclosure design. The five building material composite walls such as laterite stone, mud brick, cellular concrete, dense concrete and cinder concrete with total thirty configurations were studied. A computer simulation program was developed to compute unsteady heat transfer characteristics using the cyclic admittance procedure. From the results, it is observed that the decrement factor decreases with the increase in the divided air space thickness within the composite wall for all building materials. Dense concrete was observed to be the energy efficient from the lowest decrement factor point of view among five studied building materials. Dense concrete decrement factor decreases by 23.65% for 0.02 m air space thickness compared to the conventional composite wall without air space. It is also noticed that the time lag increases with the increase in the divided air space thickness within the composite wall for all building materials. Cellular concrete was observed to be the energy efficient from highest time lag perspective among five studied building materials. Cellular concrete time lag increases by 6.23% for 0.02 m air space thickness compared to the conventional composite wall without air space. The results of the study help in designing energy efficient building enclosures. © 2015 The Authors. Published by Elsevier Ltd.Item Study of Optimum Inward Glass Tilt Angle for Window Glass in Different Indian Latitudes to Gain Minimum Heat into Buildings(Elsevier Ltd, 2015) Gorantla, K.K.; Ashok Babu, A.B.T.Modern buildings use glass materials for building enclosures. Extensive use of glass in building envelopes increases the heat gain, which in turn increases the energy demand to maintain the building at comfortable conditions. This paper presents experimentally measured spectral optical properties of four different glass materials such as, clear, bronze, green and reflective glasses. The solar optical properties were computed using spectral optical properties. The effect of inward glass tilts to gain minimum heat into buildings for different latitudes of India with four different glass materials for energy efficient glass window design was studied. The optimum glass tilt for different Indian latitudes such as, 90, 130, 170, 210, 250 and 290 in all orientations of the window glass (E, W, N, S, NE, NW, SE and SW) were computed. From the results it is observed that at 90 and 170 N latitudes minimum heat gain is found to be in south direction for the vertical position of all the glasses. For 130 N latitude, 40 inward tilt of the glass is observed to be optimum in south direction. For latitudes 210 and 250 N, 20 inward tilt of the glass is efficient in south orientation. 290 N latitude requires an inward tilt of 60 for glass materials to eliminate solar radiation passing through the glasses in south direction. © 2015 The Authors. Published by Elsevier Ltd.Item Simulation of various wall and window glass material for energy efficient building design(Trans Tech Publications Ltd ttp@transtec.ch, 2016) Gorantla, K.K.; Saboor, S.; Ashok Babu, A.B.T.Buildings consume huge amount of energy for forced ventilation and artificial day lighting. Use of appropriate material combinations for walls and window glass can help in reducing energy consumption for cooling and lighting. This paper presents the thermal properties of four building materials such as, laterite stone, dense concrete, burnt brick and mud brick. It also presents the experimentally measured optical properties of glass materials such as, clear glass, bronze glass, green glass and reflective. In this study building of size 5m × 5m × 3.2m with four wall materials and four glass materials were designed using design builder software. The thickness of the wall was considered as external wall with thickness 0.22m. All the walls covered with cement plaster on either side. Roof of the building is made of reinforced cement concrete and floor is dense concrete. Thermal analysis was carried out using by Energy plus software. Single sized glass windows were placed in south direction (Due to less heat gain in south direction) for Mangalore city (12.87°N, 74.88°E), Karnataka, India. Different window to wall ratios (20%, 40%, 60%, 80% and 100%) were maintained for buildings. Total eighty building models were investigated for heat gain into buildings. From the results, it is observed that irrespective of the window to wall ratio, mud brick walls with reflective window glass were observed to be energy efficient from the lower heat gain point of view, and laterite stone wall building with clear glass windows were observed to be the worst due to their higher heat gain values. At 60% window to wall ratio mud brick walls with reflective window glass have 24.93kWh heat gain and dense concrete walls with clear glass have 32.9 kWh heat gain. The results of the study help in establishing the best combination of wall and glass materials for minimum heat gain into buildings. © 2016 Trans Tech Publications, Switzerland.