Heat pad for houses

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Thomas Schnabel and Jakub Gzybek at the Salzburg University of Applied Sciences
Thomas Schnabel and Jakub Gzybek at the Salzburg University of Applied Sciences are working on a heat pad for houses. Using biogenic raw materials, wood is to become the optimal heat storage medium. Tests are being conducted in research cubes directly at the Kuchl campus as well as in Sweden, Turkey and Italy.

The heating and cooling requirements of residential buildings account for around a quarter of total energy consumption worldwide. This is where the BIO-NRG-STORE research project at the Kuchl Campus of the Salzburg University of Applied Sciences comes in. An international team is researching how the use of biogenic materials can achieve a reduction in energy consumption. The focus is on how buildings can optimally store heat and use it efficiently.

Two large white cubes currently dominate the landscape at the Kuchl campus. What look like tiny houses for students are actually miniature living spaces in which researchers are measuring the influence of decentralized and hidden biogenic heat storage systems on the energy consumption of living spaces. Modified building products made of wood are used for the experiments. These materials are able to release stored thermal energy into the environment in winter and contribute to cooling the building in summer while compensating for temperature fluctuations.

"The technology in the BIO-NRG-STORE project is comparable to a heat pad for houses: It allows us to store thermal energy efficiently and release it when needed. As such, the process has the potential to revolutionize the way we heat and cool buildings. It not only offers a potential solution to increasing energy demand, but can also help reduce CO2 emissions," explains UAS- Thomas Schnabel, head of the research team at the Department of Green Engineering and Circular Design

Key technology: phase-change materials

The key lies in the use of so-called -biobased phase-change materials- (PCM) to increase storage capacity. Similar to a heat pad, these materials transform by changing their aggregate state (e.g., from solid to liquid) and can thus store heat energy and slowly release it when cooled. Impregnating wood with PCM overcomes the limited storage capacity of wood and enables efficient heat storage in buildings.

Measurement under real conditions

The central task of the Salzburg team was to -upscale- the previous laboratory tests, i.e. to test the materials on a larger scale under real conditions. Two special cubes were therefore installed on the campus grounds in Kuchl (one with PCM, one as a reference), equipped with parquet flooring and a wall covering to simulate a room situation. The initial results are very promising, as Jakub Gzybek, Junior Researcher at the Department Green Engineering and Circular Design, confirms:

-We were able to observe that the floors with impregnated middle layer of pine significantly delay the temperature fluctuations in our cubes. Here lies great potential for thermal optimization of buildings.-.

The interior finishing products were impregnated in a pressure process with bio-based fatty acids from vegetable oils, whose melting point is adjusted to the conditions of use. This modification significantly raises the heat storage capacity of the wood, so that the material has a measurable effect on regulating temperature fluctuations in interior spaces.

International trial

Supported by the FH Salzburg team, identical experimental setups have also been installed at partner institutions in Sweden (Uppsala), Turkey (Trabzon) and recently in Italy (Florence). The project team hopes that measurements at different latitudes will provide more precise information on the influence of biobased phase change materials on the indoor climate, and sees this as the basis for large-scale testing of the concept in buildings.