In order to make more energy efficient buildings it is important to reduce the energy consumption used for heating and cooling. While the daytime temperature can be too hot for comfort, the temperature at night can be too cold. The resulting need for cooling during the day and heating during the night results in an unnecessary energy consumption that can be greatly reduced by storing the energy from the excess heat during the day and releasing it back at night.
A substance that melts will absorb energy (heat) during the melting process while keeping the temperature constant until it is completely melted. This energy will be released again when the substance solidifies. This process can be used to reduce the unwanted temperature fluctuation inside buildings, utilizing a phase change material (PCM) that melts at a comfortable indoor temperature. Bulk quantities of PCMs are subject to problems that can be avoided by encapsulating the PCM into microcapsules. These microcapsules can then be added to building materials, such as concrete, in order to create a "smart" material suitable for passive house construction. It is however important to solve the problem of reduced material strength due to the incorporation of the PCM.
Addition of micro-encapsulated PCMs has been found to decrease the compressive strength of concrete. Although some speculations have been put forward, very little is actually known about the mechanisms behind this. We aim to discover these mechanisms, in order to optimize the combined mechanical and thermal properties of the concrete. This knowledge can be used to build more energy efficient buildings without adversely affecting their structural integrity.
In addition, we will gain valuable new knowledge about microcapsules. This will also be of great interest for other fields where microcapsules are utilized, e.g., medical and pharmaceutical applications, and the food and cosmetic industry.
This project is financed by the Norwegian Research Council (project number 238198).
There are 4 PhD-candidates working on this project, together with several national and international cooperation partners.
