Paul & Rosa

The two buildings Paul and Rosa were intentionally constructed using different methods. The linear building Paul features a hybrid skeleton structure with timber columns and concrete slabs reduced to a thickness of 16 centimeters. In contrast, the point building Rosa utilizes timber beam ceilings equipped with a loose expanded clay fill for acoustic insulation, along with 18-millimeter red ceramic dry screed tiles. Because the six apartments share very similar floor plans, both the technical energy consumption data and the residents subjective sense of comfort can be directly compared.

A central focus of the entire concept is the circular economy and the unmixed separation of materials. The construction strictly followed the principle of screwing, clamping, and plugging rather than gluing, ensuring that all materials can be dismantled and recycled at the end of their service life. This is particularly evident in the expanded clay fill, which was applied dry and without binders, making the ceiling construction highly suitable for future deconstruction.

Additionally, the selected building materials have a significantly reduced ecological footprint. The concrete used contains 32 percent recycled aggregate and incorporates a low-carbon cement. Transport distances were kept to a minimum, with concrete traveling just eight kilometers and the aggregates only 40 kilometers to the site. Serially prefabricated exterior wall modules – made of timber with cellulose and straw insulation for Paul, and filled prefab brick elements for Rosa – considerably accelerated the construction process. Over their entire life cycle, the buildings save around 50 percent of the CO2 emissions compared to conventional solid construction.

A specific technical detail is the building-integrated energy supply of the linear building Paul. Designed as a weather-resistant roof skin, a photovoltaic-thermal system converts solar energy into both electricity and heat, delivering 39 kW of thermal output. The roof collectors heat a brine-water circuit, which is then raised to approximately 30 degrees Celsius by a brine-water heat pump and fed into a central buffer storage tank. From there, the system directly supplies the heating circuits and the innovative concrete core activation within Pauls solid ceilings. This system takes advantage of the concretes thermal mass. In winter, the activated ceilings evenly radiate stored heat into the rooms, while in summer, they absorb excess heat to provide efficient cooling. An integrated, room-based control system allows the temperature to be precisely and individually adjusted to meet the residents needs.

Text: ZAB | Quellen: Riedel Bau AG, ASAP Institut für nachhaltige und klimagerechte Architektur GmbH, Leipfinger-Bader, IVV Magazin