Facade panels as heat sources for heat pumps

GERMANY: A concrete solar thermal building facade panel is being developed and tested as a heat source for heat pumps. 

The Tabsolar panels being developed by Germany’s Fraunhofer Institute for Solar Energy Systems (ISE) are brand new solar thermal components made from ultra-high performance concrete (UHPC). 

Available in a glazed or unglazed finish, they can be used to create an aesthetic architectural facade. Each panel is interspersed with channels containing a solar fluid, which absorbs the heat from the sun’s radiation and ambient air. This heat is then transferred via a heat exchanger into the heat pump circuit. 

The design of the channel structures is said to be created using a specially-developed Fraunhofer ISE process which produces a multiple branched pattern similar to the veins found in leaves or the human body. 

According to Fraunhofer ISE, this process makes it possible to create an evenly distributed network of channels across almost any shaped panel, which ensures uniform flow distribution and also a lower energy consumption rate for the pump. 

The panels themselves are made of ultra-high performance concrete using a membrane vacuum-forming process that is being further developed in cooperation with several industry and research partners.

As low-temperature heat sources, the Tabsolar panels are said to have the potential to provide a noiseless and attractive alternative to external air units for air-to-water heat pumps. “Our simulations suggest that both new builds and older retrofitted building stock would have sufficient facade space for this purpose,” explained Fraunhofer ISE project manager Dr Michael Herman. 

While the panels have been developed for suspended rear-ventilated facades, there is said to be potential to adapt the concept for composite exterior insulation and finish systems or sandwich wall systems in future. In addition, the panels from the Tabsolar Heat & Cool range can be installed inside buildings as thermally-activated building systems for heating/cooling.

A demonstration facade is being showcased at this weeks BAU trade fair in Munich.