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Page updated 25.7.2022


The building sector consumes a notable amount of energy worldwide. Healthcare facilities typically have high specific energy demand due to their high IAQ standards and 24 hours per day functions. One potential mechanism to reduce hospital energy consumption is demand-controlled ventilation, which is generally considered as one of the main methods in reducing building energy consumption. 

The objective of the project was to investigate the energy savings potential of hospital buildings and develop feasible demand-controlled ventilation methods and control strategies. Energy savings potential was assessed with measurements and building simulations of two case-study hospital buildings: HUS Triangle Hospital in Helsinki and Uniklinikum in Aachen. Different control strategies were studied, and the performance of these strategies related to indoor air quality and thermal comfort was tested in laboratory experiments.

The project showed that there is a notable potential for energy savings in hospital buildings with demand-controlled ventilation. Airflow reduction potential was assessed in field experiments based on occupancy estimates with room CO2 measurements. The measured occupancy rates were around 80 % for the patient and isolation rooms and 30 % for the reception, treatment, and office rooms. The reduction potential of ventilation airflow rates with demand-controlled ventilation was estimated to be 10 – 60 % depending on the space type and control strategy. Building simulations gave higher reduction potential as they also included thermal demands. In addition, the airflow rates with demand-controlled ventilation were based on recommendation in standards and guidelines whereas the measurement-based estimate used existing airflow rates in the building. The savings potential was estimated to be 60 – 90 % of the HVAC energy demand by the simulations.

The project was funded by Business Finland and the participating companies. It was carried out in international cooperation between Turku University of Applied Sciences and RWTH Aachen University.