The CO2 refrigerant, split-system heat pump water heater was tested in both lab tests and at four field sites representing the three heating zones in the Pacific Northwest. This report focuses on the field tests and the data and experience collected over almost two years of monitoring.

Prepared by:  Washington State University Energy Program

Published:  December 31, 2015

This report describes results of a scoping-level analysis of significantly higher efficiency electric heat pump water heaters (HPWH). The specific goal of the work was to identify electric HPWH design options that have the potential to achieve or exceed 30% source energy savings compared to a gas tankless water heater (GTWH) representative of the type represented in version 0.9.5.2 beta of the BEopt™ software developed by the National Renewable Energy Laboratory.

Published:  September 2011

The Building America Solution Center heat pump water heater guide provides installation guidance, training resources, standards, and case studies.

Author: U.S. Department of Energy

Publication Date: June 2015

This DOE web page highlights a range of studies into heat pump water heater performance conducted by Oak Ridge National Lab and various university and industry partners.

Author: U.S. Department of Energy

This project evaluates and documents the demand response (DR) performance of an HPWH as compared to an electric resistance water heaters (ERWH) for two primary types of DR events: peak curtailments and balancing reserves.

Prepared by:  Pacific Northwest National Laboratory

Published:  July 2013

Oak Ridge National Laboratory partnered with the Tennessee Valley Authority to investigate the load management capability by reducing the peak period energy consumption of heat pump water heaters that meet or exceed the forthcoming water heater standard. ACEEE Summer Study on Energy Efficiency in Buildings document.

Prepared by:  Oak Ridge National Laboratory and Tennessee Valley Authority

Published:  2014

The energy and cost savings potential of HPWHs as replacements for gas and electric WHs is examined in this paper. This study demonstrates the regional variations in the efficiency and economic viability of an HPWH across the continental United States for several installation locations.

Prepared by:  National Renewable Energy Laboratory

Published:  July 2013

The purpose of this project is to verify or refute many of the concerns raised by utilities regarding the ability of large tank HPWHs to perform DR by measuring the performance of HPWHs compared to ERWHs in providing DR services.

Prepared by:  Pacific Northwest National Laboratory

Published:  March 2015

Bonneville Power Administration partnered with the Electric Power Research Institute (EPRI) and Snohomish County PUD to be part of a national demonstration pilot for integrated heat pump water heaters (HPWH). 11 public utilities were selected to participate in this field test, which grew to 14 utilities.

Prepared by:  Bonneville Power Administration

Published:  October 2012

Performance Research Type:  Research Study

This paper explores the laboratory performance of five integrated Heat Pump Water Heaters (HPWHs) across a wide range of operating conditions representative of US climate regions. Laboratory results demonstrate the efficiency of this technology under most of the conditions tested and show that differences in control schemes and design features impact the performance of the individual units. These results were used to understand current model limitations, and then to bracket the energy savings potential for HPWH technology in various US climate regions. Simulation results show that HPWHs are expected to provide significant energy savings in many climate zones when compared to other types of water heaters (up to 64%, including impact on HVAC systems).

Prepared by:  National Renewable Energy Laboratory

Published:  February 2012