Main content:
Refurbishment and expansion of a school
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The main building, a typical school building from the 1960s, will be refurbished.
© Institut für Energie und Gebäude, Hochschule Nürnberg
The space requirements continually grew during the course of the years. It was also decided to bundle the specialist rooms. The secondary school, which is located in Marktoberdorf, Bavaria, therefore decided to build a second extension to the passive house standard. The existing buildings – a main building along with an extension and sports hall – were also refurbished at the same time and in energy terms brought up to the standard “30% better than EnEV” (German Energy Saving Ordinance).
Building summary
| Project status |  Projected |
|---|---|
| Location | Mühlsteig 23, 87616 Marktoberdorf, Bayern |
| Year of construction | 1960 |
| Refurbished | 2012 |
| Building owner | Staatliches Bauamt Kempten |
| Gross floor area | 14,293 m2 |
| Heated net floor area | 13,829 m2 |
| Gross volume | 67,099 m3 |
| Work places | 1,061 |
| Key aspects |
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Project description
The school previously had a gross floor area of 14,000 m² distributed across 130 rooms, of which 90 were mainly used. Since 1999, the school administrators had already spent 2 million euros in maintaining the existing buildings and a further 4.8 million euros in additional construction measures. It was now decided to fully refurbish the building and expand it with a modern building wing according to the passive house standard.
Refurbishment concept
The Marktoberdorf secondary school consists of three buildings: the main building from 1960 as well as the extension and a sports hall, which were both built in 1980. The room requirements have now grown and the intention is to bundle the specialist rooms together. For this reason a second extension with a main usable area of 1,000 m² is being constructed. This is being designed to the passive house standard. Parallel to these construction measures, the energy standard of the existing buildings shall be increased so that it exceeds the requirements of EnEV 2007 by 30%.
During the course of the refurbishment project, the thermal building envelope shall be refurbished with an additional thermal insulation composite system on the external facade (insulation thickness 24 cm, thermal conductivity group 030). Thermal insulation shall be added to the upper floor ceiling (30 cm) and the windows and external doors shall be replaced (Uw max. 1.4 W/m²K). As part of the refurbishment measures, a recreational space shall also be added in the courtyard of the existing atrium building.
Energy concept
The existing heating system will be replaced by a new heating generator (district heating using biomass-fuelled cogeneration) and a new heat distribution system installed with modern radiators and individual room regulation.
The decentralised ventilation units with heat and moisture recovery via a rotation heat exchanger are designed to ensure a good air quality with pleasant room temperatures, whereby supporting night ventilation is also envisaged. The heat recovery efficiency will be approximately 80% with a moisture recovery efficiency of around 70%. The air flow is specified in accordance with Category II of DIN EN 15251 with 7 l/s per person + 0.7 l/s m². In the chemistry laboratories and the recreational space, central ventilation units will be installed with an air volume current of 30 m³/h per person.
After the refurbishment, lighting systems with switchable and dimmable T16 strip lights and multi-voltage electronic ballasts shall be deployed with a luminous power of 10 W/m². The existing electrical installation shall be upgraded to meet current safety requirements and to enable individual room controls for the heating, ventilation and lighting functions. The building systems equipment will be regulated and controlled via a central building control system that enables simultaneous recording and evaluation of the building- and system-based data (e.g. CO2 concentration, indoor temperature, sound levels). This continual data stream will enable further optimisation of the building during operation. A photovoltaic solar power system with a surface area of 70 m² and a rated output of 10 kWp is being constructed on the roof.
Performance
Information on this subject will become available as the project continues.
Optimisation measures and possibilities
The accompanying scientific research team and the clients are analysing all building and system parts in this school project in order to determine savings objectives and comfort criteria.
Further information will be provided on this during the course of the project.
Construction costs and economic viability
During the planning phase (April 2009), the Kempten building authorities determined the following construction costs for the building measures:
- Approved construction costs according to cost group 200 – 700 (HU-Bau): 15.6 million euros
- Proportion spent on new-build measures: 4.1 million euros (26% of the overall construction costs)
- Proportion spent on refurbishment: 11.5 million euros (74% of the overall construction costs)
- Proportion spent on energy-related refurbishment: 8.9 million euros (57% of the overall construction costs)
Cost factors:
- Total construction costs/main usable area of the new building: 4,100 euros/m²
- Total construction costs/gross volume of the new building: 560 euros/m³
- Total refurbishment costs/main usable area of existing buildings: 1,850 euros/m² (45% of the new-build costs)
- Total refurbishment costs/gross volume of existing buildings: 230 euros/m³ (40% of the new-build costs)
Further information will be provided on this during the course of the project.
Educational concept
The school students and teachers will receive unrestricted access to the recorded data, thus enabling them to observe how changes in user behaviour impact on the energy consumption.
Further information will be provided on this during the course of the project.
Key energy data
| Measured energy consumption data (in kWh/m2a) | before refurbishment | after refurbishment |
| Site energy for heating and domestic hot water (dhw) | 81.70 | |
|---|---|---|
| Source energy for heating and domestic hot water (dhw) | 80.96 | |
| Total source energy | 112.24 |
Operating costs
| Operating costs in €/m2a | before refurbishment | after refurbishment |
| Heating and domestic hot water | 4.70 |
|---|
