Experimental performance evaluation of solid concrete and dry insulation materials for passive buildings in hot and humid climatic conditions

Abstract

It is known that enhancement of building energy efficiency can help in reducing energy consumption. The use of the solar insulating materials are the most efficient and cost effective passive methods for reducing the cooling requirements of the buildings. Apart from theoretical studies, no detailed experimental studies were performed in the UAE on energy savings by using solar insulation materials on buildings. Four (3m×3m×3m) solar calorimeters were built in RAK, UAE in order to perform an open air outdoor test for energy savings obtained with solar insulating materials. The design is aimed to determine the heat flux reduction and the energy savings achieved with and without different solar insulating materials, mounted at the south wall of solar calorimeters with similar indoor and ambient conditions. Experimental results are discussed to evaluate the thermal performance during high temperature conditions in summer’s period when cooling demand of the building is at its peak and also in winters when there is no cooling demand. The test is from 2012 to 2014. The controlled-temperature experimental study at a set point of 24°C showed that if the standard building material, i.e. solid concrete, is retrofitted with polyisocyanurate (PIR) and reflective coatings or completely replaced with energy-efficient dry insulation material walls such as exterior insulation finishing system (EIFS), energy savings up to an average of 7.6–25.3% can be achieved. This is due to the reduction of heat flux by an average of 22–75% at south wall during summer. Similarly, free floating analysis was done during winter and the measurements showed the behaviour of the heat flux flow and the variations in room temperature due to the variation of thermal mass caused by the difference in heat capacities of the façade with and without insulation. Heat flux and temperature variations were minimal in cases of insulated buildings when compared against a reference building in the winter free flow tests. The temperature variation is limited to 2°C in case of insulated buildings compared to 6°C in the reference case caused by high thermal inertia. Thus, insulation is essential in summer as well as in winter for the buildings in Middle East and North Africa (MENA). Overall, this paper provides a novel view on the most significant contributors to the thermal behaviour of the structure, and presents a methodology on the outdoor tests with various materials, that can significantly improve the thermal behaviour of the buildings in the extremely hot climate.