Energy-retrofitting of the Herz-Jesu Church in Munich

The Herz-Jesu church is located in Munich and was designed by Allmann Sattler Wappner Architects. The building comprises two different cubes, which are set into one another. The outer glass cube (16x21x48 m) envelopes an inner shell, which consists of more than 2.000 maple lamella. Due to the contrasting material properties of these two cubes, different colours and intensities of light shine into the church. The arrangement of the vertical lamella gradually increases the brightness of light towards the altar. At the same time, the opaque glazing prevents views into the chancel from the outside. The entrance of the building is charaterised by large, intensive blue doors, which are opened only on special holidays.

The glas facade is made of double-pane solar control glass. A part of the solar radiation is reflected; another escapes into the internal space and another is absorbed from the glasa and re-emitted als heat in the space. Automatic tiltable windows, along the facade and on the top of the building, allow for natural ventilation. Underfloor convectors, along tha facade in front of the tiltable windows, heat or cool the outside air before entering into the internal space. Because of the huge glass facade, cold air drop is a major problem affecting thermal comfort, especially during the coldest months of the year.

Research Project

Master's Degree "Energy Efficient and Sustainable Building", Technical University of Munich - TUM

Chair of Building Technology and Climate Responsive Design

Authors: Maria Voukia, Dimitra Voukia, Panagiota Mauvroeidi

German Version

SUMMER

WINTER

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A heat pump provides heating during winter by extracting heat from groundwater and transferring it into the building. A heat exchanger is in contact with the groundwater to extract or dissipate heat. In the summer, the process can be reversed so the heat pump extracts heat from the building and transfers it to the groundwater. Transferring heat to a cooler space takes less energy, so the cooling efficiency of the heat pump gains benefits from the lower groundwater temperature. Groundwater has a stable temperature of 8°C to 12°C during the whole year.

The church operates ~3400 hours per year. However, there are two different operation types. The “Basic operation”, when the church is open for visitors but no ceremony takes place and the “Full operation”, when a ceremony or concert takes place. The desirable operative temperature during “Basis operation” is ~22 °C under summer conditions and ~12 °C under winter conditions. The desirable operative temperature during “Full operation” is ~19-20 °C under both summer and winter conditions.

The main problem of the church is the inadequate thermal comfort, especially during the summer period. Between the glass and the wooden cube, temperature is often outside of the comfort range. The 16m high and 48m long glass facade has no windows or openings, which does not allow for effective natural ventilation. Furthermore, opening the large doors of the entrance of the church results in abrupt temperature changes, thus further negatively affecting thermal comfort.

Open doors, Summer

WINTER

SUMMER

The optimization proposal focuses on enhancing natural ventilation. Windows open only when the outside air temperature is lower than the operative temperature inside the church. When the outside air temperature is higher than the inside then tiltable windows close. During higher cooling loads, the chilled ceiling and the floor cooling regulate internal temperatures. Underground air ducts support natural ventilation when fresh air supply is not adequate through the tiltable windows. Fresh air supply through the underground air ducts enhance thermal comfort especially in the space between the glass and the wooden cube, Sensors regulate the opening and closing of the windows. During winter period underfloor convectors should be the main heating system as they are quick to heat giving convenient and instant warmth. For higher heating demand, underfloor heating supplies the church with additional heating.