Large Capacity CO2 Central Heat Pump Water Heating Technology Evaluation and Demonstration (LC-CO2 Project)
Research Team:
AEA (prime), Ecotope, New Buildings Institute (NBI), and Electric Power Research Institute (EPRI), Mitsubishi (manufacturing partner)
Large Capacity CO2 Central Heat Pump Water Heating Technology Evaluation and Demonstration (LC-CO2 Project)
Research Team:
AEA (prime), Ecotope, New Buildings Institute (NBI), and Electric Power Research Institute (EPRI), Mitsubishi (manufacturing partner)
Challenge
While the market for low-GWP HPWHs is beginning to grow, there is still a dearth of products currently available in the U.S. that are appropriate for use in central water heating applications in multifamily buildings. To date the only low-GWP water heating product that has been readily available in the U.S. market is one that was not specifically designed for central system applications. As a result, each project has required customized configurations that are complicated from a design, installation and operation standpoint, and lack the types of staging control options and built-in monitoring and alarm capabilities that would make them ideal solutions for larger central system applications.
Project Objective
The Large Capacity CO2 Central Heat Pump Water Heating Technology Evaluation and Demonstration project (LC-CO2) will set the stage for scaling the deployment of low-Global Warming Potential (GWP) commercial water heating systems in multifamily and commercial buildings throughout California. The project will primarily focus on the new variable capacity commercial heat pump water heaters (HPWH’s) that use CO2 as a refrigerant and are ideally suited to larger multifamily residential (40+ units) and commercial buildings. Through a series of field demonstrations, the LC-CO2 project will collect extensive real time performance data and compare operational efficiencies across a variety of design and installation approaches as well as various control and operational modes. Using the results of these demonstration projects we will create a set of standardized approaches to the design and installation of these systems and then develop a Design Guide that will enable the engineering and installation communities to easily and quickly select design approaches that are most suitable to their particular applications. Due to the thermodynamic properties of CO2, the design approaches that the team develops will be widely applicable to the entire class of large capacity CO2 based HPWHs, which we anticipate becoming more prevalent in the US market in the coming years. Additionally, we will be working closely with the manufacturers to provide product feedback and improvement recommendations. The Project Team will help the manufacturers incorporate methods of standardization that will minimize the upfront complexity for the design community. The data we collect will also be used to validate the Title-24 modeling assumptions and algorithms in the CBECC engine.
Impact
It is estimated that installing central CO2 heat pump water heaters in multifamily buildings will have the following impacts when compared to a typical gas central water heating system.
-Annual Energy Savings: 386,000 kBTU saved per year per property, resulting in a 78.5% reduction in site BTU DHW energy.
-Annual Utility Bill Cost Reductions: $200-$2,370/year per property.
-Product Cost Reductions: $16,000/unit
Peak Load Shifting: 10.1 kW/hr, or up to 50.5 kWh/day over a 5 hour peak period (4pm-9pm)
-Greenhouse Gas Emission Reductions (Combustion): 18.8-23.2 MTCO2e per year per property.
-Greenhouse Gas Emission Reductions (Refrigerant): 9 MTCO2e per system
-Air Emission NOx reductions: 24.1 lb/yr NOx
-Improved Safety: By converting from natural gas to CHPWH equipment, there will be reduced gas piping and infrastructure that could result in leaks or explosions, as well as reduced risk of localized carbon monoxide indoor air quality hazards. Additionally, new construction properties will not need to include costs for gas pipeline connections or gas piping within the building.