stuffed bricks, decrement factor, time lag, insulation
The space cooling systems account for nearly 30% of energy consumption in India. The highly insulated external walls are essential prerequisites for low energy consumption of buildings. Filling shell of the brick with insulation material is one of the methods to reduce cooling loads in buildings. This paper aims to investigate the dynamic thermal parameters of various insulation filled bricks. The dynamic thermal parameters highlighted in the study include thermal transmittance, admittance, decrement factor, time lag and areal thermal heat capacity. The cyclic admittance method was employed in computer simulation program to compute dynamic thermal parameters of stuffed bricks. The four brick materials such as mud bricks, burnt bricks, concrete blocks and fly ash bricks were selected. The insulation materials used for filling shells of the brick are foam glass and asbestos fibre. The total forty eight stuffed bricks were investigated. The shell of the brick is filled by the insulation and the each layer of insulation is separated by a brick web. The shell and web thickness of the brick were maintained as per the Indian standards. The six configurations of the stuffed bricks were investigated (1. Solid brick, 2. Bricks with the shell of the brick filled with single layer of insulation, 3. Bricks with the shell of the brick filled with two layers of insulation with each insulation layer separated with a brick web, 4. Bricks with the shell of the brick filled with three layers of insulation with each insulation layer separated by a brick web, 5. Bricks with the shell of the brick filled with four layers of insulation with each insulation layer separated by a brick web and 6. Bricks with the shell of the brick filled with five layers of insulation with each insulation layer separated by a brick web). From the results, it is observed that the stuffed bricks significantly improve time lag values as compared to the conventional solid bricks. The decrement factor decreases, admittance increases and areal thermal heat capacity increases with the increase in the number of insulation layers in the bricks. The concrete blocks with the shell of the bricks filled with five layers of asbestos fibre insulation offer the highest admittance (3.11W/m2K), the lowest decrement factor (0.435), the highest time lag values (8.26 h) and the highest areal thermal heat capacity (57366 J/m2K) among all insulation filled bricks studied. The results of the paper help in designing energy efficient stuffed bricks which can be used for construction of buildings and thereby reducing cooling loads.