Multiobjective optimization of a building envelope with the use of phase change materials (PCMs) in Mediterranean climates

Thermal energy storage applications for buildings now receive considerable attention; many systems are in development or design. Numerous studies have examined phase change materials (PCMs) incorporated into building envelopes to enhance internal thermal comfort and energy performance, while others investigated dynamic characteristics and performance of PCMs on interior surfaces. Many commercial products are currently available, but research on PCMs in Mediterranean climates is lacking. This research aims at evaluating these studies regarding the potential impact of PCM on building comfort and energy performance in Greece. The methodology intends to optimize building envelopes concerning building cooling load requirements and thermal comfort conditions. Combined dynamic simulations and multiobjective optimization, using nondominated sorting genetic algorithm-II, evaluates design options of typical office spaces: an undivided and a fully subdivided office space, respectively. Specifically, combinations of insulation and thermal mass materials are examined quantifying thermal storage potential: as sensible storage with conventional materials or latent storage with PCM. Several PCMs, with varying melting points, are evaluated in addition to operation schedules enhancing PCM performance. Specifically, the thermal characteristics of 2 commercial products (MicronalBasf® PCM and SP-24® from Rubitherm Technologies GmbH) are initially modeled, and several hypothetical materials are subsequently defined and evaluated. This work attempts to determine suitable applications of PCM in Mediterranean climates and evaluate their performance. The numerical results evaluate measure appropriateness, and possible trade-offs are discussed.