Pilot Case 1: Aachen (GE)

Implementation at the German pilot site

The physics building of RWTH Aachen University was chosen as the German pilot building. It is an institute building with offices, laboratories, lecture and seminar rooms. For the implementation of the Plug and Harvest façade system, we consider three rooms on the southern façade of the building.

The facade of the building is a unitized facade with metal elements 3 meters high and 1.2 meters wide. The elements are divided into two parts. In the lower part (1.1 meter high) a sandwich panel (white coloured) is installed as a balustrade element. In the upper part a glazing is mounted. Each floor has its balcony which can be used as an escape route in case of fire. The balconies are concrete slabs, laying over concrete beams.

PnH Façade design

On the German pilot building a total number of 11 facade modules are installed. This corresponds to a façade area of 47.5 m² and affects three offices. The façade consists of eleven aluminium frames with a total size of 300 cm x 120 cm. Since the installation is only intended to be temporary, the existing facade is remained intact as much as possible. This means that the existing windows, as well as the shading system, are not dismantled. Instead, the new facade system is simply positioned in front of the shading system. Glazing is provided in the upper part of each module. Here, fixed glazing always alternates with openable glazing. The openable windows will be vertical sliding windows. A total of six openable and five fixed glazed windows is installed.

The window areas have a total height of 190 cm, whereby 90 cm can be opened for the sliding windows. Below the windows, there are balustrade elements with a height of 110 cm. The balustrade modules are partly insulated and partly equipped with technical components. Aluminum panels as the facade cladding are chosen in the design of PnH façade to mimic the existing cladding design of the old façade for a more integrated appearance.

A number of aspects have been taken into account during the technical implementation on the German pilot building. A good overview of the installation can be obtained by looking at the sectional view. The newly added facade is highlighted with red. An essential aspect in several respects is the absolute depth of the PnH system. Since the balconies are escape routes in the event of fire, it must be ensured that there is a continuous width of at least one meter between the facade and the railing.

Structural realization

The special static situation of the existing building requires the installation of a substructure. For this purpose, a steel structure is fixed between the cantilevered beams of the prefabricated reinforced concrete balconies. The steel substructure consists of two hat profiles per balcony bay that are screwed to the beams. Between the top hat profiles, an L-shaped profile is fixed. The PnH modules are connected to the substructure. The installation is done in 3 steps. First, the frame of the PnH modules is attached to the substructure. Then the new glazing is inserted. Finally, the new technical modules are inserted into the parapet area. Parapets without technology are insulated and clad. A video showing the installation can be found here

Implementation of technical components

Each of the three rooms is equipped with a technical device integrated into the façade – in total three different devices are installed. The selection of the technical equipment is based on the measurement data of the one-year monitoring phase. The monitoring showed that the rooms are rather too warm true for almost the whole year. Due to high internal and solar gains, it is assumed that the radiators in these rooms are almost not needed. On the contrary, measures to reduce temperatures in the summer and transition months are more likely to be necessary. For this reason, the planning does not include devices such as solar air heaters. Instead, the installation of façade-integrated reversible heat pumps is aimed at, since these have both heating and cooling functions and can thus react flexibly to the requirements in the rooms.

In the room with the highest pre-retrofit temperatures, a reversible monobloc heat pump is installed. Because of its small installation depth, we decided to use a monobloc device from the Italian company Olimpia Splendid with the name Unico. The device was intended for installation in the building and requires two core drillings through the outer wall for the supply of outside air, as heat source for heat pump operation or sink in cooling mode. For both heating and cooling power, a nominal power of approx. 2kW can be assumed.

In the other two rooms, two different ventilation units with heat recovery function are installed. The figure shows in the middle picture the integration of a decentral ventilation unit in one of the rooms. The device was pre-assembled on the inner panel in advance to the work on the construction site and placed with the exchange of the inner panel. It has an operating panel on the inside, with which the user can control the operation of the device. Only one air duct is needed for the device, as it is separated in inlet and outlet flow.

The third room is ventilated by a central ventilation system with heat recovery as shown on the right picture. With a central ventilation unit of the used type, it would be possible to supply several rooms with one device. However, to have the possibility to compare several devices in the other rooms, the unit only supplies one room.

Monitoring system and sensors installed

A monitoring system was installed 1.5 years before the retrofit. The measurements will be carried out for up to one year after the retrofit. In each of the rooms, the following sensor types are installed: CO2, humidity and indoor temperature measure, Presence & Illuminance detector, Door and Window Sensors, Heat flow meter, Electricity meter. The sensors transmit their measured values via the Z-Wave protocol to several Raspberry Pie single-board computers positioned in the rooms. Via the WLAN network of the RWTH the measured values are then stored on the project server.

The PnH building automation system will be able to control the HVAC devices as well as the radiators in each of the rooms to ensure a high user comfort at low energy demand. Monitoring data after installation shows an improvement of thermal comfort temperatures in the active cooled rooms in summer and will be further evaluated.