14 October 2016
CO2 heat pump water heaters (HPWH) represent the most energy efficient and eco-friendly heat pump technology
for domestic hot water (DHW) heating. After the fundamental research at NTNU-SINTEF in Norway during the 1990s and the commercialisation in Japan in 2001, components and units have reached a high technological level for both residential and non-residential applications. In Japan more than 5 million residential CO2 HPWH have been sold, and in recent years an increasing number of large-capacity CO2 HPWH for e.g. blocks of flats, hotels, hospitals, nursery homes and sport centres have been installed in Asia, Europe and the USA. This article provides an overview of the basis of the technology, and presents some interesting installations in Norway, the origin of the technology.