Office cooling with air or with chilled beams from an energy perspective

Even in cold climates, offices normally need to be cooled due to the internal heat loads from people, equipment and lighting. Either a chilled ceiling or chilled beams with cooled water as medium or chilled air can be used. In the case with chilled ceiling or chilled beams, a constant air volume system (CAV) is used. In the case of air only, a variable air volume (VAV) system must be used. This paper presents the advantages of the two methods of cooling with respect to energy use, which was calculated from climate data. The characteristic of the Northern European climate is that there are few annual hours where the outdoor temperature exceeds the indoor temperature. Therefore, it is often possible to cool a building without cooling the supply air. Less energy was needed by the VAV system since free cooling can easily be applicable in combination with the commonly larger dimensions in the VAV system and thereby lower pressure drops.