abstract
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The use of phase change materials in building envelopes has attracted the attention of researchers to minimize cooling and heating loads and for thermal comfort regulation. A research gap was found regarding the numerical analysis of lightweight roofs with PCM considering conjugate heat transfer. Thus, this paper aims to evaluate the thermal performance of a lightweight hollow concrete roof with a phase change material (PCM) in a subhumid climate. Three roof configurations with two PCMs were numerically analyzed through computational fluid dynamics. Simulations were conducted using the open-source code OpenFoam and were verified and validated with good agreements proving the confidence of the proposed methodology for building envelope design purposes. The roof configurations with fully-filled PCM exhibited the best thermal behavior, reaching higher temperature reductions between 1.4 °C to 2.0 °C, respectively, and reductions of indoor peak heat flux by approximately 47 % compared with the reference case. The roof fully-filled with an inorganic PCM with a melting temperature of 25 °C was the most energy-efficient roof configuration because it achieved the highest energy savings of 65.5 %, lowest electricity costs of 0.85¿4.33 USD m¿2, and lowest CO
2 emissions of approximately 18.31 kgCO2 e m¿2. The results demonstrated that the utilization of PCM into lightweight concrete roofs in subhumid climates is very promising. © 2024 Elsevier B.V.