## 1 Introduction
Last but not least, practical examples of encapsulations for commercial PCMs (Table 13 p. 1693) are presented. Issues related to over-cooling and possible segregation are also treated. Similarly, in [5], the same \"taxonomy\" is taken to classify the various applications, although a specific attention is given to glazing and shadings and blinds (Section 5 pp. 62-63) and to HVAC (Section 6 p. 63), and in [10]. Finally, in [7], after some basic recalls about thermal energy storages and PCMs properties, various criteria are furnished in order to help in the design and for the choice of the appropriate candidate. When turning to the encapsulation techniques, one can consider [4; 6] for the micro-encapsulations and [8] for the nano-encapsulations. If one now turns to more specific reviews, the cooling applications are addressed in [11; 12; 13; 14; 15] while specific papers are available for the appliances (or active systems), such as PV [16] and solar domestic hot water systems [17; 18] or heat-pumps [19; 20]. The use of PCM in structures, and the associated boons and banes, can be found in [21; 22; 23; 24; 25; 26; 27; 28], the specific topic of mortars being detailed in [29; 30]. [PERSON] and [PERSON] [29], after some classic recalls about PCM and their incorporation processes, propose a brief survey on the various mechanical and thermal properties determination. However, only a few numerical and practical data are available, before some discussion on their stability. In [30], [PERSON] et al. first show that, for mortars, PCMs are mainly studied in combination with cement (Figure 11, p. 104). Secondly, their global impacts are well described, with an useful summary for the micro-encapsulated PCMs in Table 4, p. 105. Then, an extended analysis of the mechanical and thermal properties is given (see Table 6, pp. 114-115). As a rule of thumb, it appears that the determination of their effective intrinsic properties is the key factor when trying to retrieve and characterize the thermal behavior of such materials. In other words, only a confident and secure characterization will permit to estimate their real boons for buildings applications. In this respect, this is the unique solution to perform reliable and realistic simulations. This issue has been tackled by many authors:  
* the thermal conductivity is searched for in [31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46] using either hot wire [31; 45], hot plate [32; 34; 35; 36; 39; 42; 43; 44; 46], or laser flash [33; 40] techniques. Let us mention here that the thermal contact resistances and their influence on the measured conductivity are rarely taken into account. * the heat capacity is mainly investigated as an apparent capacity, which is supposed to integrate the latent heat and goes continuously from the solid value to the liquid one [31; 33; 34; 36; 37; 38; 40; 44; 45; 47; 48; 49; 50; 51; 52; 53]. However, many of these studies determine this property from a differential scanning calorimetry (DSC) experiment [33; 34; 38; 40; 44; 45; 47; 48; 49; 51; 53; 54; 55], where the size of the sample is such that it is not very representative of the macroscopic material [5; 31; 36; 52]. As far as real scales are concerned, one can also note the possible use of the dynamic heat flow meter method (DHFM), which resembles the isothermal mode of calorimeters [56; 57]. Practically, this apparent capacity is very often obtained by directly integrating the heat-flow rate. Unfortunately, it can potentially lead to inconsistent or imprecise characterization [58; 59; 60; 61; 62] and be responsible for erroneous predictions when modeling the macroscopic material [60; 63; 64]. * in recent studies, a more generic approach based on inversion methods has been developed in order to determine separately the main thermo-physical properties, such as the heat capacities (solid and liquid) and/or the latent heat etc. [36; 52; 65].