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External sun protection and passive house windows contribute to the good energy balance of the refurbished vocational college in Detmold.
© Yagmur Bildik, iFE Institut für Energieforschung
School refurbishment
Projektinfo 09/2018

Site plan: The extensions (an administration area, a learning area and a teaching restaurant) that were built prior to the refurbishment are marked in green.
© Harald Semke, pape oder semke ARCHITEKTURBÜRO

Summary: Built-in components
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Refurbished vocational college achieves energy-plus level

Since its refurbishment, the vocational college in Detmold generates more primary energy than it consumes. For this purpose, the facades and the top storeys have been insulated with cellulose, passive house windows have been installed and the roof areas have been covered with PV panels. The existing heating system continues to be used with reduced temperatures. Since 2016, there has been a comprehensive monitoring of its operation.

In 2008, the district council in Lippe decided to refurbish its own properties with passive house components and to use roof areas for the generation of solar power. When the complete refurbishment of three buildings and a gymnasium built between 1954 and 1962 on the campus of the Felix Fechenbach Berufskolleg in Detmold was needed, an energy-plus school was designed.

All facades and roofs have been insulated with cellulose. The perimeter insulation goes right down to the foundation. Passive house windows have replaced the old wooden and aluminium windows. On the gently sloping roofs, photovoltaic modules took on the function of the roof envelope. The buildings have continued to be supplied with district heating from biomass – good for the primary energy balance. In the course of the underground construction work, the pipes were also replaced and insulated.  he considerably better building insulation has made it possible to reduce the supply temperatures and to adapt the operational times. In order to reduce losses from the circulation pipes, the domestic hot water supply has been replaced.

In addition to opening the windows, the classrooms are mechanically ventilated via decentralised devices with heat recovery. For test purposes, two rooms are also equipped with ceiling fans. In the case of lighting, presence- and daylight-controlled fluorescent lamps were already installed in most places; in the remaining areas LED technology is now installed.

The minimal change in the building fabric, the refurbishment during ongoing use of the buildings and the use of the existing heating and distribution costs considerably less than a new build or a refurbishment with a new supply design. At the same time, there are aboveaverage energy savings – not just in its operation, but also in its fabrication. The design won the “School 2030” idea competition conferred by the German Federal ministry for Economic Affairs and Energy.


Majority of predictions are correct

As proven by the monitoring performed by the Ostwestfalen-Lippe University of Applied Sciences, the school has already been achieving the objective of the primary energy energy-plus balance since its completion in 2016. The refurbishment has reduced the final energy consumption for heat by approx. 65%. After the refurbishment, the provision of the domestic hot water still consumes roughly twice as much energy as predicted. Despite the pipes being retrofitted with insulation and reducing the consumption points to a few rooms, the pipe and storage losses make up more than 90%. Currently, the scientists are investigating the causes and optimisation options.

In two classrooms, the consumption and loads are recorded: the biggest electricity consumption is caused by the white board including a teacher’s PC at approx. 4.3 kWh/(m² p.a.); a system with which the school was already equipped before the refurbishment. The decentralised ventilation device consumes between 2.3 and 3.3 kWh/(m² p.a.) depending on occupancy density and teaching hours. The daylight-controlled lighting requires 1.7 to 2.0 kWh/(m² p.a.). On the operation of the ceiling fans, a linear correlation to both the outside air temperature and the average room air temperature becomes apparent. They consume approx. 0.4 kWh/(m² p.a.). The energy consumption of the fixed heating in the classroom is approx. 24 kWh/(m² p.a.) and in comparison to the initial state, it has been reduced by over 80%. However, that is not solely down to the refurbishment, but it was rather optimisations after the first year of operation that reduced consumption in the classroom by a further 21%.

Projektinfo 09/2018:
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BINE-Projektinfo 09/2018
(pdf, 4 pages, 269 kB)


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