Study on the thermal performance of a multi-layer structural green roof panel / Abdullah-Al-Mamoon

Abdullah, Al-Mamoon (2017) Study on the thermal performance of a multi-layer structural green roof panel / Abdullah-Al-Mamoon. Masters thesis, University of Malaya.

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Abstract

The indoor condition of a building is one of the most important concerns for the occupants which is affected by climatic conditions. During a typical summer day, solar radiation heats up a building through the windows, walls, doors and especially the roof. To maintain indoor comfort during the summer, the heat gained must be removed by a cooling system. The energy is used for cooling purposes to make indoor comfort for the building’s occupants. As a result, energy savings is a major focus in building design and requires systematic investigations. It is suggested to make a proper roof design to ensure a comfortable temperature inside a building. The main aim of this research is to demonstrate the effectiveness of the design concept on the impact of air gaps driven by forced ventilation effects to reduce the attic temperature. This temperature reduction contributes to the enhancement of the comfort of the residents. In this study, eight different indoor roof models were designed and experiments were carried out by using solar simulator. Their performances were evaluated among the roof designs regarding the attic temperature reduction. The main feature of the roof model is an Aluminum and PVC tubes (which act as a moving-air path), placed on the underside of the roof. The roof inclination angle was 30º to the horizontal. An insulation layer and ventilation fans were integrated with the roof. These ventilation fans can help to remove the hot air to the surroundings. The thermal performances of the roof models were evaluated by measuring the reduction in attic temperature for each of the roof designs compared with a standard Design-A as a baseline. Among all the designs, it was found that Design-H is 8.99 % more efficient in attic temperature reduction than the standard roof Design-A due to metal roof, insulation, MAP (moving-air path) and ventilation fan which contribute to the decrease in the heat flow. The Design-H which consisted of an insulation layer, fans (airflow in moving-air path, Vair = 1 – 1.9 m/s) and PVC tubes showed a significant improvement in the reduction in attic temperature of 3.2 ºC compared with the conventional roof model (33.7 ºC in the attic). The theoretical calculation showed that the annual energy savings can be as high as 37.35 kWh/m2 by using optimum conditions in roof design. The annual cost saving of energy per unit of area is increased by up to US$ 2.24/m2 by using roof Design-H. Furthermore, Adaptive Neuro Fuzzy Inference System (ANFIS) is applied as a soft-computing method to determine the predominant variables that affect the thermal comfort in the building. Five input parameters were used to compute the output parameter which is the attic temperature. The outcome of this method showed that the combination of mass flow rate and ambient temperature is the primary factor and has the best predictor accuracy for thermal comfort in the building. All of these significant findings indicate that the cooling system in the roof provides a new design paradigm with greater temperature reduction and reduces the annual energy consumption.

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