Radiant Cooling, Thermally Activated Building System, Glass Fibre Reinforced Gypsum, Passive Cooling
Globally, building sector consumes a large amount of energy both for construction and operation. Especially, heating, ventilation, and air conditioning contribute for 40 – 50% of total building energy consumption. Thermally Activated Building System (TABS), which is an energy efficient alternative for conventional mechanical air conditioning, can reduce the energy consumption of building operation. TABS is based on radiant cooling, which also utilizes the thermal mass of the building to achieve thermal comfort of the indoor space. In TABS, chilled water is circulated through the pipes embedded in the building structures. Chilled water removes the heat from the indoor and provides comfort to the occupants. In addition to TABS, use of appropriate building material can enhance the energy-saving potential of buildings not only by reducing the cooling/heating load but also by reducing the embodied energy of the building. Therefore, the building material is also focused in the present study. A sustainable and eco-friendly building material namely Glass Fibre Reinforced Gypsum (GFRG) is integrated with the TABS. The air cavities in the GFRG panels reduce the solar heat penetration through it. In addition, the low thermal conductivity of GFRG reduces the heat transfer from outdoor to indoor. Thus, reduction in cooling load and therefore enhancement in energy saving can be realized. The combination of TABS and GFRG is named as Thermally Activated Glass Fibre Reinforced Gypsum (TAGFRG). The present study aims to analyze the impact of various design and operating parameters on the performance of TAGFRG roof. The roof has copper pipes embedded in the bottom half of the panel cavities, whereas the top half of the cavities have air gaps. A commercial CFD tool has been used to simulate the TAGFRG. The design and operating parameters analyzed are the diameter, wall thickness and thermal conductivity of pipe, pipe spacing, and temperature and flow rate of supply water. The results conclude that the temperature of roof bottom surface decreases with the increase in diameter and thermal conductivity of pipe, and decrease in wall thickness and spacing of pipes. The average bottom surface temperature of the roof is 31.9°C for no cooling case. This reduces to 20°C for the supply water temperature of 16°C with the average heat removal of 120 W/m2from the space by the bottom roof surface.