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Thermal energy storage (TES) is a technology with a high potential for different thermal applications. It is well known that TES could be the most appropriate way and method to correct the gap between the demand and supply of energy and therefore it has become a very attractive technology. In this paper, a review of TES for cold storage applications using solid-liquid phase change materials has been carried out. The scope of the work was focussed on different aspects: phase change materials (PCM), encapsulation, heat transfer enhancement, and the effect of storage on food quality. Materials used by researchers as potential PCM at low temperatures (less than 20 ºC) are summarized and some of their thermophysical properties are reported. Over 88 materials that can be used as PCM, and about 40 commercially available PCM have been listed. Problems in long term stability of the materials, such as corrosion, phase segregation, stability under extended cycling or subcooling are discussed. Heat transfer is considered both from theoretical and experimental point of view and the different methods of PCM encapsulation are reviewed. Many applications of PCM at low temperature can be found, such as, ice storage, conservation and transport of temperature sensitive materials and in air conditioning, cold stores, and refrigerated trucks.

It is well known that there is a need to develop technologies to achieve thermal comfort in buildings lowering the cooling and heating demand. Research has shown that thermal energy storage (TES) is a way to do so, but also other purposes can be pursued when using TES in buildings, such as peak shaving or increase of energy efficiency in HVAC systems. This paper reviews TES in buildings using sensible, latent heat and thermochemical energy storage.Sustainable heating and cooling with TES in buildings can be achieved through passive systems in building envelopes, Phase Change Materials (PCM) in active systems, sorption systems, and seasonal storage.

During the last decade, vertical greenery systems are increasing their presence in building designs, providing several urban ecosystem services. One of them is the potential to provide energy savings in buildings, which develops an important role, however, data about its performance during winter periods is still scarce. Therefore, the main objective of this paper is to compare at real scale the thermal performance of two different vertical greenery systems implemented in experimental houses-like cubicles for both cooling and heating periods. A double-skin green facade has been installed in the first cubicle that uses deciduous creeper plants, while the second one is designed with green walls made with evergreen species. Finally, a third identical cubicle without any green coverage is used as reference. Two different types of experiments have been carried out to test the performance of the house like-cubicles. One consists of controlling the internal ambient temperature providing heating or cooling to maintain the desired comfort conditions. On the other hand, to study the thermal response of the construction system, the heating, ventilation and air conditioning system was disconnected and the cubicles were tested under free floating condition. First results showed a high potential for energy savings during cooling season for green wall (58.9 %) and double-skin green facade (33.8 %) in comparison to the reference system. On the other hand, for heating periods no extra energy consumption was observed for evergreen system.

13Energy consumed by heating, ventilation and air conditioning systems (HVAC) in 14 buildings represents an important part of the global energy consumed in Europe. 15 Thermal energy storage is considered as a promising technology to improve the energy 16 efficiency of these systems, and if incorporated in the building envelope the energy 17 demand can be reduced. Many studies are on applications of thermal energy storage in 18 buildings, but few consider their integration in the building. The inclusion of thermal 19 storage in a functional and constructive way could promote these systems in the 20 commercial and residential building sector, as well as providing user-friendly tools to 21 architects and engineers to help implementation at the design stage. The aim of this 22 paper is to review and identify thermal storage building integrated systems and to 23 classify them depending on the location of the thermal storage system. 24 25 26 Keywords: thermal energy storage (TES), building integration, active system, phase 27 change materials (PCM), thermal mass 28 29 30 35Solar applications, including those in buildings, require storage of thermal energy for 36 periods ranging from very short duration (in minutes or hours) to seasonal storage. The 37 main advantage of using TES in solar systems for buildings is the success of converting 38 an intermittent energy source in meeting the demand, which may be intermittent and/or 39 have a time shift [2]. TES can also be used for free-cooling of buildings. The advantage 40 here is the use of a natural resource for air conditioning in buildings. 42Advantages of using TES in an energy system are the increase of the overall efficiency 43 and reliability, but it can also lead to better economic feasibility, reducing investment 44 and running costs, and less pollution of the environment and less CO 2 emissions [3]. 45 Thermal energy can be stored using different methods: sensible heat, latent heat and 46 thermochemical energy storage [1,2,3]. 48Sensible storage is the most common method of heat and cold storage. Here energy is 49 stored by changing the temperature of a storage medium (such as water, air, oil, rock 50 beds, bricks, concrete, or sand). The amount of energy stored (Eq. 1) is proportional to 51 the temperature difference, the mass of the storage medium, and its heat capacity:where Cp is the specific heat of the storage material (J/kg·°C), ΔT the temperature 56 gradient (°C), m the mass of storage material (kg). 57 58 Latent heat storage is when a material stores heat through a phase transition. Usually the 59 solid-liquid phase change is used because of its high enthalpy and lack of pressure 60 problems. Upon melting, as heat is transferred to the storage material, the material 61 maintains a constant temperature constant at the melting temperature, also called phase 62 change temperature. The amount of heat stored can be calculated by Eq. 2. 63 64 3 h m Q    (Eq. 2) 65 66 where Δh is the phase change enthalpy, also called as melting enthalpy or he...