Long-Term Energy and Moisture Performance of Reflective and Non-reflective Roofing Systems with and Without Phase Change Materials Under Kuwaiti Climates

Abstract

Numerical simulations are conducted in this paper to investigate the hygrothermal performance of white and black roofing systems with and without Phase Change Materials (PCMs). The roofs considered in this paper are three roofing systems, namely, reference roof without drywall, reference roof with drywall but without PCM, and roofing system with PCM drywall of different melting temperatures. These roofing systems are subjected to the weather conditions of Kuwait city. In order to find out whether white roofs could lead to moisture-related problems, the numerical simulations are conducted for a period of 5 years. In case of the moisture accumulation is still increasing after 5 years on year-to-year basis of comparison of moisture, the period of simulation will be extended accordingly. The results show that no risk of condensation and mould growth occur in black and white roofing systems with and without PCM. In addition, the results show that white roofs experience an increase in the heating energy loads compared to black roofs. However, the decrease in the cooling energy loads for white roofs are typically much greater than the increase in the heating energy loads. As such, white roofs result in a net energy savings compared to black roofs. Furthermore, the results show that the months of the highest total energy loads for different roofing systems occur in July and August. The main outcome of this paper shows the capabilities of using reflective materials with different short-wave solar absorption coefficients and PCMs with different melting temperature for enhancing the energy performance of the roofing systems.