The National Renewable Energy Laboratory (NREL), in partnership with Oak Ridge National Laboratory, under the Clean Energy Manufacturing Analysis Center (CEMAC ) 1 umbrella, assessed the current state of existing and low-global-warming-potential (GWP) refrigerants for major end-use applications, including heating, ventilating, and air conditioning (HVAC) and those outside of the HVAC industry. The project incorporated a market overview and supply chain assessment to determine the production, distribution, consumption, costs, and potential operating efficiency impacts of new and alternative refrigerants entering the market. Market trends and ongoing research are also documented. This work supplements other U.S. Department of Energy efforts to support research activities on refrigerants and their applications, including a refrigerant research and development roadmap (Goetzler et al. 2014) and an outlook into global air-conditioning markets (Goetzler et al. 2016).

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NOTICEThis report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof.

NOTICEThis report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Executive SummaryPhase change materials (PCMs) represent a potential technology to reduce peak loads and heating, ventilation, and air conditioning (HVAC) energy consumption in buildings. A few building energy simulation programs have the capability to simulate PCMs, but their accuracy has not been completely tested. This report summarizes NREL's efforts to develop diagnostic test cases to conduct accurate energy simulations when PCMs are modeled in residential buildings. Overall, the procedure used to verify and validate the conduction finite difference (CondFD) and PCM models in EnergyPlus is similar to that dictated by American Society of Heating, Refrigerating and Air-Conditioning Engineers Standard 140, which consists of analytical verification, comparative testing, and empirical validation. Validation was done in two levels (wall or building) for the two algorithms (CondFD and PCM). The wall-level tests were very detailed and focused on a single wall subjected to particular boundary conditions on both sides for a relatively short duration. In contrast, the whole-house tests focused on an entire building, considering interactions between the building envelope, HVAC, and internal loads for periods that varied from a few days to a year. This process was valuable, as several bugs were identified and fixed in both models. EnergyPlus will use the validated CondFD and PCM models as a basis for version 7.1.This study also includes a preliminary assessment of three residential building envelope technologies containing PCM: PCM-enhanced insulation, PCM-impregnated drywall, and thin PCM layers. These technologies are compared based on peak reduction and energy savings using the PCM and CondFD algorithm in EnergyPlus. Preliminary results using whole building energy analysis suggest that considerable annual energy savings up to 20% could be achieved using PCMs in residential buildings. However, careful design is needed to optimize PCM solutions according to the specific user goals for peak demand and energy use reductions. Optimum design should also include several variables such as PCM properties, location in the building envelope, and local climate. Futur...