General information

Year of construction:  2009 - 2010
Number of pupils:  540
Number of classrooms:  18
Gross floor area:  7,414 m²
Useful floor area according to EnEV:  6,563 m²
Heated net floor area (energy reference area):  6,563 m²
Gross volumen:  38,184 m³
Heated volume:  29,217 m³
A/V:  0.39 1/m

Integrated technical and architectural concept
Up-to-date pedagogical concepts recognize that the learning behaviour of pupils depends directly on the room conditions. Requirements for elementary schools no longer define lessons by classical lecture style teaching but by a self-contained process that is moderated by the teacher with individual promotion of single pupils or groups, variuous classroom situations, active participation by the pupils, project work and the use of different media. Room concepts shall be characterized by transparency and openess of space. At the same time it is necessary to create areas that provide shelter, affiliation and identification -  especially for small children. The resulting functional flexibility requires new room concepts which can't be fulfilled by the traditional classroom with a black board wall, seating rows and light from the left. Instead, differentiated, divisible and versatile rooms are needed.

The technical concept is linked directly with the room configuration. The daylighting has to cope with different classroom situations. The aim is to realise a high daylight autonomy accompanied by high quality electrical lighting (e.g. limitation of glare) for varying classroom situations.

The ventilation concept is derived from the flexible room situation. In the cloak rooms and wash rooms which are directly assigned to the different classrooms (home area), mechanical ventilation is needed anyway, but is now used to secure a basic ventilation for the whole home area. In addition to this basic ventilation, a natural ventilation by automatically controlled windows is foreseen. The natural ventilation can either be controlled according to the individual requirements in the home area or centrally.

Room acoustics is of major importance and an optimum combination of thermal active building masses and absorption areas has to be developed.

Building components

In the building envelope, the thermal losses were avoided to a large extent by fulfilling the passive house requirements.  Besides the highly insulated construction, an airtight envelope (n50 < 0.6 1/h) and a balanced ratio between transparent and opaque facade areas, thermal masses and acoustic elements are also of importance.

The walls consist of reinforced concrete, mineral wool and a facade with brick facing, resulting in an U-value of 0.13-0.15 W/m²K. At the ballustrades on the south side and at some small thermal bridges, vacuum insulation is used. The windows consist of aluminium/wood frame constructions with triple panes and a U-value of 0.8 W/m²K. The green roof with an U-value of 0.11 W/m²K is made of concrete plus an insulation made of 35 cm of polystyrene aggregate. The concrete bottom slab is insulated by expanded polystyrene and has an U-value of 0.10 W/m²K.

Building service systems
Due to the synchronised development of energy and building concepts, a high integration of the architectural design and the building service system could be achieved. The use of natural processes and passive technologies have been the basis for minimising the active technical components and realising a lean-building concept. Thus the life-cycle costs of the building service systems could be reduced and the energy demand of the building could be significantly decreased.

The energy concept comprises:

• a building envelope according to the passive house standard
• a building structure with plenty of thermal mass for free cooling to reduce overheating in summer and increase the user comfort
• a room concept enabling daylight from multiple sides, offering a high daylight autonomy and thereby reducing the electricity consumption
• a lighting concept with presence sensors and separate controls for the deeper room areas in order to limit the electrical lighting
• a hybrid ventilation concept based essentially on natural ventilation an using mechanical ventilation only when necessary
• a sustainable energy generation from renewable energy sources (wood pellet boiler and wood pellet combined heat and power unit) which secures a CO2 neutrality and fulfills the energy surplus concept

Sustainable energy supply

The energy generation system consists of the following 3 parts:

• wood pellet boiler: capacity 220 kW, for the main load
• wood pellet combined heat and power unit: capacity 10 kW, for small and permanent load and the generation of electricity
• PV unit: 55 kWp, for the generation of electricity

Energy consumption

On the one hand, the energy surplus concept is based on the minimised energy demand of the building and the efficient building service system and on the other hand, the use of locally available renewable energy sources to supply the demand (zero emission strategy). By generating electrical energy through the CHP and the pv unit, the primary energy demand of the school is compensated for and in the annual balance, more primary energy is produced in the school than consumed. Additionally CO2 neutrality is achieved.

Costs

The energy surplus concepts allows for compensating a significant part of the energy costs by the earnings from the electricity generation. The building costs are comparable with conventional buildings.

Net building costs related to m² gross floor area (according to DIN 276):

• building construction (KG 300): 767 €/m²
• building service systems (KG 400): 220 €/m²

Funding
The project is being financially supported by the Federal Ministry of Economy and Technology within the research initiative focus "Energieeffiziente Schulgebäude - EnEff:Schule".

More information is available in German here.