One Machine for Heating, Cooling, and Domestic Hot Water: Multi-Function Heat Pumps to Enable Zero Net Energy Homes

摘要

The evolution of heat-pump technology promises a revolution for residential energyrnefficiency. While traditional residential mechanical design uses multiple systems and fuels tornprovide thermal services, the emerging generation of heat-pump technologies can providernheating, cooling and domestic hot water with a single appliance. These heat pumps operate overrna wider temperature range than their predecessors, offer substantial efficiency improvements,rnand introduce opportunities for waste heat recovery. The domestic hot water heating market isrnbeginning to experience this change as air-source heat-pump water heaters deliver obviousrnenergy savings over electric-resistance water heaters; and (arguably) also beat condensing gasfiredrnsystems in terms of source energy consumption and greenhouse gas emissions. However,rnwe anticipate that the current introduction of stand-alone heat-pump water heaters is only thernfirst step in a transition toward multi-function heat-pumps that can replace conventional airconditioners,rnfurnaces, and hot water heaters. The study presented draws from multi-season fieldrnmeasurements of operation and performance for several multi-function heat-pumps. The researchrnassesses the overall efficiency of these systems, and compares the advantages and disadvantagesrnof alternative designs. Our research provides monitored examples of air-source heat pumps,rngeothermal heat pumps, water-to-water systems, and desuperheaters. We also describe the designrnof the multi-function heat pump at the core of a zero-net-energy demonstration home designed torngenerate enough electricity to also power the annual drive cycle of an all-electric sedan. Thernheat-pump in this home is designed to cover all heating, cooling and domestic hot water needsrnwith no backup.