Fraunhofer ISE develops façade elements as a heat source for heat pumps

The Fraunhofer Institute for Solar Energy Systems ISE is developing solar thermal façade elements together with industrial partners in the »Tabsolar III« project funded by the German Federal Ministry of Economics and Climate Protection (BMWK). As low-temperature heat sources for heat pumps, these façade elements offer a noiseless alternative to outdoor air units of air-to-water heat pumps. The Tabsolar elements are made of ultra-high performance concrete (UHPC) with channels through which a solar fluid flows. The heat absorbed by the fluid is then given to the heat pump circuit through a heat exchanger. »Our simulations suggest that both new builds and older retrofitted building stock would have sufficient façade space for this purpose,« explains Michael Hermann, coordinator of the collaborative research project and project manager at Fraunhofer ISE.
In the Tabsolar III project, the use of the new façade elements is being tested from the preliminary planning stage through planning, production and installation to operation, with the involvement of the respective trades. The yield of the system could only be determined in simulations so far, which showed about 240 kilowatt hours (kWh) per square meter and year for a south-facing façade with unglazed collectors; with glazed collectors, 400 kWh or more could be possible. At Fraunhofer ISE, however, it is assumed that for common façade surfaces, the outdoor air unit of a heat pump can be replaced by Tabsolar elements.
At the BAU trade fair (April 17-22, Munich), Fraunhofer ISE will present a demonstrator as a ventilated curtain façade with two hydraulically connected Tabsolar design samples.
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