Westend Buildings for Mixed Use, Bad Aibling, Germany

Two new buildings (approx. 11,000 m²) with high environmental quality and energy efficiency are planned at the corner of Münchner- and Westend-Straße in Bad Aibling.
An integrated energy concept has been developed for the building complex, which will mainly be filled with apartments, but also with retail space on the ground floor and office space on the first floor.
The first objective was to reduce the heating and cooling requirements as much as possible. The building envelope is thus very efficient (EnEV standard for insulation) and the windows are fitted with triple glazing. The solar factor of the glazing is 50%, in order to limit overheating in summer, but also to take advantage of passive solar gains in winter. Fresh air is supplied to the homes and offices by inlet air elements (decentralized ventilation) integrated into the facade. The fresh air can be preheated in winter to avoid cold draughts, using low-temperature radiators. Exhaust air is made via a central extraction system with a heat pump, which recovers heat from the extract air (65%). For rental spaces, a conventional central ventilation system will be provided, due to the larger air volumes required.
Night cross-ventilation (80% of the apartments have a double orientation) combined with the thermal mass of the slabs will make it possible to reduce daytime temperature peaks during the summer period. Exterior solar protection will also be provided on all facades (except for the retail space) and will help to reduce the overheating of the buildings in summer.
Radiant systems (floor heating and cooling) for heating and cooling the buildings are planned. These are low-temperature systems and therefore more environmentally friendly.
For the new building, the estimated heating (including hot water), cooling and electricity needs are respectively 518 MWh/a, 82 MWh/a and 456 MWh/a. The peak powers are 550 kW and 150 kW for heating and cooling respectively.
An ecological and economic comparison of different energy supply options has shown that ground water energy for heating (using a heat pump) and cooling (free cooling!) combined with a gas boiler for winter peak heating is the best supply option. In regards of the future decarbonisation of the German electricity mix, this supply option will become even better from an ecological point of view in the future.
Half of the roofs will be saved for renewable electricity generation. Approximately 1000 m² of photovoltaic modules will be installed and will produce 233 MWh/a of renewable electricity on site. Thus, by avoiding the purchase of electricity from the grid, approximately 113 tons of CO2 can be offset. These 113 tons compensate for the total CO2 emissions for the heating and cooling supply of the buildings and more than 40% of the total energy demand (heating, cooling, electricity).