Latent heat thermal energy storage systems incorporate phase change materials (PCMs) as storage materials. The high energy density of PCMs, their ability to store at nearly constant temperature, and the diversity of available materials make latent heat storage systems particularly competitive technologies for reducing energy consumption in buildings. This work reviews recent experimental and numerical studies on the integration of PCMs in building envelopes for passive energy storage. The results of the different studies show that the use of PCMs can reduce the peak temperature and smooth the thermal load. The integration of PCMs can be done on the entire building envelope (walls, roofs, windows). Despite many advances, some aspects remain to be studied, notably the long-term stability of buildings incorporating PCMs, the issues of moisture and mass transfer, and the consideration of the actual use of the building. Based on this review, we have identified possible contributions to improve the efficiency of passive systems incorporating PCMs. Thus, fatty acids and their eutectic mixtures, combined with natural insulators, such as vegetable fibers, were chosen to make shape-stabilized PCMs composites. These composites can be integrated in buildings as a passive thermal energy storage material.

Raw earth is one of the oldest building materials of mankind. Almost a third of the world’s population is living in an earth-based house. However, their use remains low compared to conventional materials such as concrete, steel, and wood. Although these geosourced materials are abundant, recyclable, and have a low environmental footprint, their use is very limited in the construction sector. This can be explained by the lack of data regarding their hygrothermal behavior. In this context, the present work aims to highlight the properties of cob construction material with straw addition. An experimental characterization of hygrothermal and microstructural properties has been carried out. Thermal conductivity, specific heat, sorption isotherms, moisture storage capacity, moisture buffer value (MBV), and water vapor permeability are obtained experimentally. Then, the collected data are used as input parameters of a numerical prediction model to numerically assess the thermal and hygric behavior. Cob is then compared to other more commonly used materials to highlight the benefits of its use within the context of the energetic and environmental transition. Our results will allow better understanding of the behavior of the new geosourced material thanks to experimental and numerical investigation.

Buildings are submitted to various external and internal solicitations that could affect its energy performance. Among these solicitations, temperature and moisture play a crucial role and could irrevocably affect the comfort of the occupants and the indoor air quality of the living environment. To assess the impact of the solicitation on building performance, a precise modeling of the heat, air, and moisture transfer phenomenon is necessary. This work proposes an extensive review of the hygrothermal models for building envelopes. The different models are divided into nodal and HAM techniques for heat, air, and moisture (HAM) transfer models. The HAM approach has been classified based on four driving potentials: moisture content, relative humidity, capillary pressure, and vapor pressure. Phase change materials (PCMs), alongside hygroscopic materials, enhance building thermal capacity and energy efficiency. There are various approaches to studying phase changes, with enthalpy-based and heat capacity approaches being the most popular. Building performance can be improved by combining PCM thermal inertia with hygroscopic moisture management. This review has exhibited the need for numerical models that address phase change and moisture behavior in these hybrid materials, capable of controlling temperature and humidity.