Fig. 25a: The Imtech building in Hamburg: Testing ground for 50 PCM ventilation modules.
© Imtech

Fig. 25: The Imtech building in Hamburg.
© Imtech

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In practice

Testing of a decentralised PCM ventilation device

As part of a demonstration project, 50 modules from the ventilation and cooling system developed by Imtech, with a PCM graphite composite material as storage medium, were installed in an administrative building – one module for every 7 m² of office area. This corresponds to a PCM distribution of 5 kg/m² and a storage capacity of 0.14 kWh/m². Preliminary building simulations showed that the installed modules should be capable of keeping the operative temperature almost permanently under 26 °C during normal summers. The tests started in March 2006 showed that the system is capable of cooling the indoor air by up to 5 K before it is returned to the room again. A maximum cooling capacity of 300 W was achieved. Relative to a conventional system with a compression refrigeration machine, the new system provides 82% of the cooling with only around 5–7% of the electricity consumption. It thus provides energyefficient room cooling during the day with electricity savings of between 60% and 90%. PCM ventilation devices including control units have been commercially available since 2007. They are currently being adapted for use in patients’ room and hotel rooms.

LowEx research focus

LowEx stands for “Low-exergy technologies”. Various innovative technologies for buildings, building services technology and energy supply are being developed here that have one thing in common: They work with the lowest possible differences in temperature to the room temperature for heating and cooling, aswell as for distribution of heat and cold within rooms. Renewable energy sources can also be used in this manner – for example, the natural low temperatures of the ground or of ground water can be used for cooling, and solar thermal energy for heating. LowEx is one focus of the German Federal Ministry of Economics and Technology’s “Energy-Optimised Construction” (EnOB) research initiative.

Further information can be found on the Internet at www.enob.info


The increasingly widespread availability of PCM technology has made quality assurance more important. For this reason, a number of German companies founded the Quality Association PCM e.V. in 2004 and employed the Bavarian Center for Applied Energy Research (ZAE Bayern) and the Fraunhofer Institute for Solar Energy Systems (ISE) to develop suitable quality assurance procedures. The goal here was to ensure the quality of the storage materials themselves aswell as that of buildings and systems that contain these storage materials. The RAL quality seal was awarded in June 2008 after this work was completed. The main criteria for this seal are the amount of heat stored as a function of temperature, the cyclical repeatability of the storage process, and the thermal conductivity of the storage materials, which is important for the charging and discharging times of the storage devices.


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