Fasomvandlingsmaterial : Brandrisker med energilagring i byggnader

Sammanfattning: Energy storage with the help of different materials is something that has been around for a long time. Structures such as concrete or brick use their high thermal mass to store energy in the form of temperature increase, sensible heat, of the respective material. Energy storage in the form of sensible heat is relatively small in capacity, which means that large masses of building material are required to give a significant effect. Concrete, for example, requires 4 kJ/kg to increase in temperature by 1 °C. Now society has begun to look more closely at other materials that can be used for energy storage and temperature stabilization in buildings. Phase change materials are unique materials that use the change in phases between different aggregation states to store energy in the form of latent heat. It is mainly phase change between solid and liquid that is used since gaseous form would involve large volume changes. An everyday example of a material that undergoes a phase change is water. Water requires 334 kJ/kg to go from 0 ˚C ice (solid) to 0 ˚C water (liquid).  Water is a very powerful phase change material but cannot be used in buildings as it melts at 0 ˚C. Therefore, other materials have been developed to meet the requirement that the melting take place at the desired temperature, usually room temperature. The different phase change materials can be divided into three different groups: organic, inorganic and eutetic materials. All groups come with their own advantages and disadvantages. Organic materials are stable materials in the sense that they can phase change in repeated cycles which makes them the popular choice when it comes to buildings. One disadvantage that most organic materials possess is that they are flammable. The choice of phase change material will affect the quality of the building and it is therefore important that the knowledge about these materials is adopted before they become more widespread.