Herlev Hospital saves energy

Heat recovery and a new concept for separate heating and ventilation will generate annual energy savings worth more than 5 mill. DKK (700,000 EUR) plus a better indoor climate for the hospital's patients and staff

Herlev Hospital's approx. 200,000 m2 are heated by hot air. The systems are some of Europe's largest for the purpose of heating buildings. However, they are worn out and consume a lot of energy per m2 – and do not create an optimum indoor climate.

Separate heating and ventilation with VAV

As part of a comprehensive modernisation and rebuilding project, Herlev Hospital, in co-operation with Balslev, is conducting several energy optimisation projects. These include:

  • The segregation of heating and ventilation with a separate ventilation system of the type VAV (Variable Air Volume) plus a modification from high pressure to low pressure ventilation
  • Installation of a radiator based heater system
  • Heat recovery.

”The background for these project were a strong wish for a better indoor climate and to significantly reduce our energy consumption plus to recover energy, because our heating system also keept the birds warm, so to speak," says Herlev Hospital's technical manager, Arno Hansen. ”Heating with ventilation results in very dry air in the winter, dry mucous membranes and static electricity. In the summer, it causes draughts because of the strong need for cooling and as a consequence of ineffective vents in the ventilation system's air intake."

Initial experiences: Reduced energy consumption and increased operational reliability

In 2007, in connection with the establishment of a new stem cell laboratory, Herlev Hospital, together with Balslev, conducted a pilot project with modication of the axial exhaust fans. ”Therefore, we already have positive operational experience with axial exhaust fans, which offer better modulation possibilities," says Arno Hansen. ”This confirms that our ideas were right - with regard to both lower energy consumption and increased operational reliability."

Ventilation and heat recovery controlled on a per needs basis

Already in 1994 Balslev identified a simple way to obtain quick energy savings in the existing ventilation system of the building dedicated to patient care: We installed a section valve, which closed off the ventilation outside opening hours. This generated substantial savings. In the long-term, the entire hospital will have ventilation controlled on a per needs basis, where the amount of air is automatically adjusted according to the actual needs and use, e.g. in operating theatres. 

Annual savings of at least 5 mill. DKK (700,000 EUR)

In order to achieve further energy savings, Herlev Hospital has been granted authorisation to establish heat recovery in connection with the ventilation systems in the treatment building's block 5 and in the ward's block 1. ”We can significantly reduce our energy consumption by recovering heat, which is otherwise discharged through the chimney. The five-year old recovery system in the service building has paid for itself," Arno Hansen emphasizes. ”When the entire project is implemented, the estimated savings from heat recovery and exchange of the axial exhaust fans are estimated to be in the vicinity of at least 5 million DKK (700,000 EUR) per year. In addition, we anticipate savings from the ongoing conversions from high pressure to low pressure ventilation with VAV."

”Balslev is just as familiar with the technical installations and operating conditions at Herlev Hospital as we are," says Herlev Hospitals technical director, Arno Hansen. "Balslev's engineers have provided an overview of our total energy consumption, identified substantial savings and delivered reports and proposals, which formed the basis for a number of energy projects with significant, measurable results.”

Further information

The projects were described in an article in the magazine  Hospital, Drift & Teknologi, of the Danish Union of hospital engieers Sygehusmaskinmestre i Danmarks fagblad

Other projects

Herlev Hospital has used Balslev as consultants for many years e.g. in connection with:

  • Installation of new operating theatres
  • Laboratories
  • Other specialised hospital wards
  • Consulting on energy optimisation
 

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