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Fig. 18: Engelhardt & Bauer printing house in Karlsruhe after comprehensive refurbishment measures.
© Patrick Beuchert

Fig. 18b:Engelhardt & Bauer printing house in Karlsruhe after comprehensive refurbishment measures.
© Patrick Beuchert

Fig. 21: DAW cooling ceiling with a cold water system as a heat sink.
© Fraunhofer ISE

Fig. 22: CHCP system implemented at the Fraunhofer ISE for cooling an open-plan office using cooling/heating convectors and for five offices using a PCM cooling ceiling.
© Fraunhofer ISE

Fig. 23: Temperature profiles in a PCM-cooled office.
© Fraunhofer ISE
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In practice

Refurbishment of a printing house:

Cooling using environmental energy in combination with thermo-active building systems and PCMs

The administration building at the Engelhardt & Bauer printing house in Karlsruhe is a commercial facility from the 1970s that had typical weak points such as high energy consumption, insufficient daylight and poor thermal comfort. This low-rise building has now been fully refurbished and extended by one storey (usable floor area of 900 m², building volume of 3,000 m³), and is a pioneering project: A high-class architectural solution was found for a lightweight construction building with a high percentage of glass, using commercially available products and services.

The use of PCMs is one possibility for adding thermal mass to lightweight structures without adding significant weight. 260m² of ceiling cooling panels from ILKAZELL were first installed in the upper storey. These combine BASF’s latent heat storage medium in the form of a conventional smartboard (melting temperature 22 °C) with active cooling using capillary tube mats. The area available for the PCM cooling ceiling was defined by the building geometry, meaning that the heat transfer capacity was limited to around 12 kW. On the basement level, plastered capillary tube mats were fitted to the existing concrete ceiling as a quick additional system with a capacity of around 10 kW.

The thermal, visual and acoustic comfort was improved relative to the original situation, and the energy requirements for heating, cooling, ventilation and lighting were reduced by 50%. The existing split devices for cooling provision were replaced by energy-efficient cooling using thermo-active building systems. The ground was used as a natural heat sink, which was exploited using 13 borehole heat exchangers at a depth of 44 m. Despite the building’s lightweight steel construction, a stable indoor environment is achieved in the summer. The energy transferred using the PCM ceiling cooling panels was 80 kWh/m² of ceiling area p.a. for the 2008 operating year. Alongside sizing the equipment correctly and choosing the individual components, the control of the system was the critical factor in delivering energy-efficient operation.

Demonstration building with PCM cooling ceilings

As part of the “PCM active” project, two different PCM cooling ceiling systems have been implemented in demonstration buildings. The laboratory building at Deutsche Amphibolin-Werke (DAW) in Ober-Ramstadt, which has around 100 m² of ceiling area, has a cooling ceiling based on a 1-cm layer of PCM filler containing around 40% of PCM, with recooling using a cold water system installed outdoors. The goal here was to demonstrate that conventional cooling technology can also benefit from being combined with a PCM cooling ceiling. The two main gains here are the reduced operating periods for active cooling and the shifting of recooling into the cooler night-time period.

A PCM cooling ceiling with a combined heating, cooling and power (CHCP) cogeneration system as a heat sink has been fitted to five offices at the Fraunhofer ISE in Freiburg (which also has around 100 m² of total ceiling area). This system consists of a CHP plant that is used for generating electricity. The waste heat from this plant is converted into cooling capacity using adsorption chillers and then passed on to the consumer loads. The cooling system (with around 11 kW of thermal capacity) supplies an open-plan office during the day through heating/cooling convectors, as required. The five PCM cooling ceilings are only cooled at night, so that they can passively cool the office areas the following day. The combination of two consumer loads operated in turn results in significantly improved utilisation of the CHP plant without having to provide large heat storage tanks. Thus, the office area that is cooled can be doubled even with a cooling system of unchanged size. Figure 23, with data from summer 2008, demonstrates that this concept works in practice. The graph shows the temperatures of the room, plaster and water in one of the offices. At an outside temperature of up to 30 °C, room comfort is maintained with a maximum temperature of 25 °C. At the same time, the PCM storage capacity is sufficient to provide passive cooling for a whole day. Only around 3 p.m. do the ceiling temperatures leave the PCM’smelting range (grey highlighting).

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