Summary
The increased use of solar energy is a useful way of saving on heating energy. Passive use with large areas of glazing and the use of transparent façades can bring a notable reduction in primary energy consumption. However, this innovative construction method requires summer overheating problems to be taken into account. Self-regulating overheating protection systems could be one solution to the problem.
As part of this collaborative project, intelligent thermotropic, non-mechanical shading systems will be developed, providing overheating protection for glazing and transparent heat insulating façades by utilising thermally triggered switching operations. The systems were constructed based on polymers with thermo-reversible morphology. Above a certain temperature, the heat energy arriving with sunlight causes these polymer systems to automatically become cloudy. The process is reversible, i.e. as the temperature drops again, layers of these polymer systems become transparent. The clouding reduces transmission of solar radiation and thus limits energy input.
The partners focused on developing and processing thermotropic polymer blends and hydro gels, producing prototypes, characterising them in application-based tests and conducting stability studies.
Results:
- Work on a thermotropic hydro gel had to be discontinued as the long-term stability of the systems could not be ensured.
- With switching temperatures in the 25 °C range, the thermotropic polymer blends met the requirements for automatic sun protection.
- Long-term stability studies on the thermotropic polymer blends were unable to verify a service life of more than 10 years.
- The critical factors for the new system are successful stabilisation of the thermotropic layers to guarantee an adequate service life and the possibility of producing the layers by extrusion.
