KARLA - New Administration Office, Karlsruhe, Germany

KARLA - New Administration Office

A complex of flat-roofed and a 295 ft / 90m high-rise building will replace the old district administration building. In addition to offices, there will be space for the Accident Insurance Fund of Baden-Württemberg, the Administrative and Economic Academy, an occupational health practice, and a daycare center.

The energy concept aims for a balanced CO2-neutrality, meaning the building must completely offset the CO2 emissions it produces during an operational year with locally sourced renewable energy, generated here through photovoltaics. The energy demand must be kept as low as possible, and the team will use passive strategies and exploit synergies to achieve this. Based on simulations using the extreme weather dataset provided by the German Weather Service (DWD), Transsolar examined usage areas concerning comfort and energy demand, developed a concept for high thermal comfort and maximum flexibility for each area, and tested for maximum robustness. Passive measures include a compact building form and high insulation standards for the façade. The glazing will be designed to optimally combine daylight availability with thermal protection in both summer and winter. External slatted shading lets in sufficient light thanks to individually adjustable daylight control while simultaneously reducing solar heat gain and, therefore, the cooling demand. A double façade surrounds the high-rise, shielding it from wind and weather while also dampening external noise, even with windows open, supporting prolonged natural ventilation. Adequate air exchange and good air quality by low-tech, low technical effort and low energy demand, are key elements of the concept. Energy efficiency is enhanced when the ventilation system and conditioning are technically separated. The flat-roofed building is designed with mechanical basic ventilation, with all areas that permit natural ventilation featuring operable windows. The high-rise will have basic ventilation via floor-by-floor dedicated ventilation systems with heat recovery. Outside air is centrally drawn in, and exhaust air is expelled through another central duct.

A hydraulic surface system will be used for heating and cooling. All heat and cooling consumers, apart from hot water preparation, are designed for energy-efficiency with low flow temperatures for heating and relatively high temperatures for cooling. In the flat-roofed building, heating and cooling ceilings are provided for the thermal conditioning of rooms. Modules support diverse uses, allowing for quick responses to special situations, and reconfigurations can be carried out with minimal effort. Underfloor heating is planned for the lobby, dining room, and daycare center. To temper the space in summer, the floor system can be supplied with cold water. The homogeneous use of the high-rise allows for an activated clay ceiling system, providing a stable indoor climate thanks to thermal mass and passive natural regulation of humidity. Due to local conditions, geothermal energy via earth probes, wastewater, ice storage, and district cooling are excluded as energy sources. Subject to approval, geothermal use through wells remains the primary source, with cooling provided through outside air and a reversible heat pump as the central element to cover the base load for heat and cooling generation. The utilization of waste heat within the building is the most efficient form of simultaneous heat and cooling generation. Two sprinkler tanks can also be used as cooling buffer storage, decoupling heat and cooling demand while maximizing the share of waste heat utilization. District heating from the municipal utility covers peak heat loads, while compression chillers with dry coolers on the flat-roofed building serve to meet peak cooling loads.

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