## 1 Introduction  
Wood is a widely used material in several industries such as construction and furniture. Its renewable nature, ease of transformation, and mechanical properties tend to make it the material of choice for several architects and designers. As wood is a porous material, it is possible to enhance its properties by impregnation or by the application of a coating. In recent decades, several treatments were applied on wood to enhance its durability [1], reduce its flammability [2], or increase its mechanical properties [3]. Such treatments can be opaque or translucent and can induce physical and/or chemical modifications within the wood. Impregnation can be achieved with pressure in a reactor. Several techniques were developed, such as Lowry, Ruping, or Bethell [4], and consist of different pressure cycles of pressure and/or vacuum. Phase change materials (PCMs) are able to store a high amount of latent heat in a small material volume. Most of the time, this is achieved by a solid/liquid transition. Historically, paraffin PCMs have been widely used [5; 6]. Recently, multiple studies are focused on organic bio-based PCMs, for their better fire resistance [7], great chemical stability [8], and possibly low environmental impact [9]. Several studies found out that PCMs can increase the thermal mass of buildings and thus lead to a higher energy efficiency [10]. During the heating season, such materials are able to store solar energy within the day. This energy is then released at night, reducing the need of heating [11]. During the hot season, the PCMs can store the heat overflow and thus reduce the building's overheating [12]. With proper night conditions, the PCM can solidify and act again the next day. Implementing a PCM within a building is complex and multiple factors need to be considered, such as the climate, building architecture, and users' behavior. A good understanding of the melting and solidification dynamics is required to predict the PCMs behavior in buildings. Several studies are focusing on this point [13; 14]. PCMs integrated in walls have already demonstrated potential benefits through multiple experimental studies [15; 16]. In order to be protected from the environment, PCMs need to be encapsulated. This also prevent any leakage when the PCM is in the liquid state. There are several ways to protect the PCM such as macroencapsulation, microencapsulation, or directly by molding a shape-stabilized material [8]. Microencapsulation has become a common way to protect the PCMs and thus to incorporate it in various components. Several techniques are used to manufacture microcapsules such as coacervation [17], interfacial polymerization [18], or spray-drying [19; 20]. Capsules have to be strong enough to sustain the stress that is generated according to the volumetric change during the phase change process [21]. Urea-formaldehyde (UF) resin, melamine-formaldehyde (MF) resin, and polymers such as polyurethane (PU) are the most common shell materials for PCM microencapsulation [22]. There are a few trials of PCM composites using wood as a substrate. [PERSON] et al., proposed in 2012 to add microencapsulated PCMs (MPCMs) in a wood adhesive to enhance wood flooring thermal mass [23]. Bonding strength remained good, but thermal mass enhancement was low, due to the small quantity of MPCMs added in the glue (maximum 10% of the glue mass). In 2016, [PERSON] et al. shaped wood plastic composites by mixing microcapsules of dodecanol with wood flour and high-density polyethylene [24]. Their composites have shown a modulus of elasticity between 0.9 and 2.2 GPa, and 20.3 J/g of latent heat. Increasing the ratio of MPCP would reduce the mechanical properties of the composite. In 2018, [PERSON] et al. prepared a decorative wood panel loaded with bio-based PCMs macroencapsulated in a polyethylene bag [25]. They obtained a panel with a maximum heat storage of 57.1 J/g. In 2016, [PERSON] et al., impregnated green fir wood (_Pseudotsuga menziesii_) with polyethylene glycol (PEG).