A comprehensive field test to study the operating details of a representative water-loop heat pump (WLHP) system has been carried out for three years in a commercial office building in Stamford, Connecticut. The large body of results has shown that the WLHP system studied provides satisfactory comfort in all seasons and is very reliable but that there are many areas in which energy efficiency and cost-effectiveness could be improved. These results have provided insight into the energy use demand of the system and its components in all seasons, characterised the interactions of the components with each other and with the building and its controls, and provided the opportunity to identify WLHP system configurations and develop improved operating and control strategies. Summarises the findings for the specific test site and seeks to apply them to the WLHP field as a whole. The test site is a modern, all-electric, five-storey building with 72,000 ft2 of conditioned office space having well-defined core and perimeter areas on the upper floors, with two parking floors below. The WLHP system is two-pipe and incorporates representative current core and perimeter heat pumps, a 300-kW electric boiler, and closed-loop cooling tower.

KEYWORDS: testing, optimisation, heat pumps, water heat pumps, designing, performance, commercial, offices, USA, energy conservation, costs, economics, energy consumption, components, operations, controls, multistorey buildings, all electric, air conditioning, thermal comfort, case studies