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Optimisation of Ventilation Systems in the BG Klinik Ludwigshafen

Wyróżniony Przypadek December 2013
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In the context of the Re-Co european project, the energy performance of the emergency hospital BG Klinik Ludwigshafen which is one of the largest accident-surgical centers in Europe, is being improved.


General data:

Name: BG Klinik Ludwigshafen

Location: Ludwigshafen am Rhein (Rhineland-Palatinate, Germany)

Climate: mild humid temperate

Building type: hospital

Project type: re-commissioning

Designer: Steinbeis Transferzentrum Energie, Gebäude und Solartechnik Stuttgart (STZ)

Net heated floor area: 68 000 m2

Number of beds (2011): 545

Number of ambulant patients (2011): 25 241

Number of stationary patients (2011): 11 887


Energy consumption and energy costs:

Primary energy demand: 25 000 000 kWh/y

Energy cost: 2 700 000 €/y


Re-Commissioning steps:

First, a rough analysis was carried out on energy bills to determine how the energy consumption was divided among the different final uses. This resulted in an energy flow chart (Figure 1) pointing out the main energy uses.

From the energy flow chart it is clearly visible that the ventilation systems need approximately 45% of the total energy used. This corresponds to about 54% of the clinic’s total energy costs.

For the detailed analysis, the operation of the selected ventilation systems was simulated under current operating conditions and yearly energy consumption was calculated. Afterwards, the energy saving potential was calculated through adapting the actual system use in cooperation with the technical staff, the users and involved companies (Figure 2).

The calculation for the individual ventilation systems (Figure 3) showed the energy saving potential to be in the range from 4% to even 58% with average savings of more than 35% of the initial energy demand (Figure 4).

These savings were reached by implementing low or no-cost measures. The highest potential was found in measures adjusting the supply to the demand of ventilation, such as:

  • shutting down the system overnight
  • reducing the volume air flow rates
  • adapting the actual time profiles in the building management system to its real use (Figure 5)
  • adopting a more effective model of uses of ventilated rooms.

Other measures increasing the energy efficiency were

  • reduction of set point values of the supply air pressure
  • replacement of damaged regulating flaps in distribution systems
  • checks by several controls of the volume air flow rates.

The result in the BG Klinik Ludwigshafen shows that large energy savings can be reached simply by adapting set point values and time profiles of the ventilation systems in the building management system.

Energy costs of about 170 000 euro per year could be saved in the clinic by investing about 110 000 euro. The identified measures are amortized after less than one year.

Since the start of the Re-Co project, approximately 8% savings of heat and electricity was achieved through optimization of the ventilation systems.


Further activities:

In 2012, 12 of the total 31 ventilation systems were optimized (with no-cost investments):

  • adaption of utilization times
  • reduction of systems air pressure
  • reduction of air volume flow rates
  • overnight shutdown.

Thus obtaining about 2 500 MWh savings per year (7% of the energy consumption).

In 2013 further actions (with low-cost investments) were planned:

  • heat recovery will be installed in 2 existing ventilation systems
  • a bypass will be installed in the central heat recovery and in the central preheater to reduce the pressure drop, when possible
  • old fans will be replaced by more efficient ones, with electronic controls of velocity (and frequency changers).

Thus obtaining about additional 750 MWh savings per year.

Furthermore, 6 more ventilation systems will be optimized and the heat supply will be analyzed in detail.


Re-Co is a European project focused on the development, demonstration and promotion of re-commissioning projects, as energy saving projects with no and low-cost investments.

The Re-Co general goal is reducing energy cost through optimization of existing building systems and user behavior. The concrete target is 10% of primary energy savings through no or low-cost measures, focusing on existing non-residential buildings, particularly in the health sector, universities and office buildings. 

The Re-Commissioning approach is based on 5 key components:

  1. Energy information systems
  2. Data analyses and selected measurement
  3. Optimization of existing building technologies and systems
  4. Information and motivation of building occupants
  5. Performance measurement and quality assurance.


Lessons learnt

Measures of optimization for complex ventilations systems give good benefits with short payback periods. They become rather sophisticated in terms of knowledge, experience and field surveys, and they require suitable tools to be used by experts.

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