Plus energy schools in Germany - pilot projects and key technologies

In 2008 the German Ministry of Economic Affairs and Energy launched an initiative for new or retrofitted energy-efficient school buildings as focus area within their research programme "EnOB" (Energy Optimised Buildings). The initiative (www.eneff-schule.de) comprises three different energy levels: -Best practice schools with energy-efficient renovations above the requirements in the energy-saving ordinance - Three-liter-house schools with energy needs for heating, hot water and auxiliary below 34 kWh/m²year - Plus energy schools that produce more energy than they use in the annual balance Currently three different plus energy school buildings have been planned, realized and monitored within the initiative, two of them being renovations (Stuttgart and Rostock), the last one being a new school building (Hohen Neuendorf). The three energy concepts include rather different technologies to generate heat and to reduce the energy consumption of ventilation and lighting systems. This is partly due to the research initiative approach of "EnEff:Schule" that asks for testing innovative technologies. There is however a general tendency to: - Low U-values of the building envelope with about 0.11-0.15 W/m²K at the walls and roof, 0.10 W/m²K for new base plates and 0.20-0.34 W/m²K for renovated ground slabs and basement ceilings and 0.80 W/m²K for windows - Large PV areas to compensate for the remaining energy use, sometimes in combination with other technologies or systems that generate electricity - Mechanical ventilation systems with high heat recovery rates but in combination with natural ventilation - User-dependent control strategies for ventilation and heating - Use of daylight at both the window/solar shading side and the electrical lighting control The paper compares the different technologies used at the building envelope, the heating, ventilation and lighting systems, the calculated and measured energy consumptions and the building costs.