Presentation of the first combined CO2 heat pump, air conditioning and hot tap water system for a hotel in Scandinavia

Abstract

Hotels are high-energy consuming buildings with numerous demands for heating and cooling at several temperature levels. The heating load is largely dominated by hot water production (28%: NVE, 2016) in order to meet the hot water consumption of the many guests. The current practice is to have several independent heating and cooling systems. Most of the hotels in northern Europe use thermally inefficient methods, such as electric boilers or district heating stations, which simultaneously provide high temperature heat for tap water and a high temperature space heating circuit. Currently, CO2 technologies are widely used in Scandinavia at an industrial scale thanks to their high efficiency in cold climates. The first combined CO2 heating, air conditioning and hot tap water system with an integrated thermal storage for a hotel is installed (2018) in Norway (Trondheim) and is presented in this paper. The working principal of the system is clearly described in this work and data obtained from the first test campaigns are presented. The heat pump has an installed capacity of 280 kW. If cooling is needed, chilled water for AC cooling is used as a heat source. Heat is rejected to two different circuits in the gas cooler in order to achieve high and medium temperature levels according to the setpoint of the different heating applications. The tap water system is mainly composed of a 6 m3 buffer tank storage unit, in order to ensure continuous production of hot water to covers the peak demand period. Preliminary results show significant energy savings (59-68%) and peak power reductions (15-45%).