The effect of free-cooling and demand-based ventilation on energy consumption of self-regulating and traditional chilled beam systems in cold climate

This paper presents the energy saving potential of free cooling and demand-based ventilation with chilled beam system. In the analysis, there are two beam concepts: standard chilled and a self-regulating chilled beam systems. Instead of a traditional four pipe configuration, the self-regulating chilled beam system comprises of a two pipe system, allowing it to utilize high temperature water for cooling and low temperature water for heating, respectively. In self-regulating system, there is no need for regulation valve for beam: the inlet water temperature is close room air temperature (20-22°C) and the room air temperature is allowed to vary between 21-25°C depending on the load conditions. The free cooling for the inlet water is provided by the preheat coil of the air handling unit. The introduction of demand-based ventilation further increases the energy efficiency of the FIVAC system. Energy consumption of the robust self-regulating system is slightly higher than with traditional chilled beam system because self-regulating system is able to keep the room air temperature lower than with traditional beam system. With free-cooling, it is possible to save about 15% of the delivered energy. With the occupancy ration of 60%, energy consumption is reduced 36% with demand-based ventilation. When both free-cooling and demand-based ventilation are used with 60% occupancy ratio, the energy consumption is 44% lower than with traditional system.