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Title: To Duct or Not to Duct: Evaluating the Space Conditioning Impacts of Heat Pump Water Heaters in the PNNL Lab Homes

Heat pump water heaters (HPWH) are a promising technology for substantially reducing water heating-related energy use in the residential sector. However, concerns have been raised regarding the impact of HPWHs on space conditioning energy when installed in conditioned space, primarily in northern climates. For example, the Northwest Energy Efficiency Alliance (NEEA’s) Northern Climate HPWH Specification, which describes the characteristics a HPWH must have to be incentivized in cold climates in the Pacific Northwest (PNW), requires exhaust ducting for their Tier II-specified products and both supply and exhaust ducting for the Tier III-specified product (NEEA 2013). However, these concerns and installation recommendations are based on modeling and comparative field data are not available to verify modeled performance. This study examines the overall performance and operation of two GE GeoSpring HPWHs in conditioned space in the matched pair of PNNL Lab Homes with no ducting, exhaust ducting, and full ducting (supply and exhaust) and explores the interactions between the HPWH and the home’s heating/cooling system. The data collected in this field evaluation suggest that previous modeling may not completely characterize the complex interactions of HPWHs, HVAC systems, and ducting. This report discusses the impact on space conditioning and water heater energy usemore » of configuring an HPWH with exhaust only ducting or full ducting, as compared to an unducted HPWH. Additional cost analysis is necessary to assess the cost effectiveness of ducting and to make formal recommendations regarding appropriate installation of HPWHs in more varied scenarios.« less
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Resource Relation:
Conference: ACEEE Summer Study on Energy Efficiency in Buildings: The Next Generation: Reaching for High Energy Savings, August 17-22, 2014, Pacific Grove, California, 1-364 - 1-378
American Council for an Energy-Efficient Economy, Washington DC, United States(US).
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
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Country of Publication:
United States
heat pump water heater; energy efficiency; space conditioning interaction