ET22SWE0028 - Packaged Central CO2 Heat Pump Water Heater Multifamily Demonstration
AESC and ASK Energy propose a California-focused field demonstration and market assessment of a packaged, modular, all-electric CO2 centralized heat pump water heater with load shift capabilities designed for commercial and multi-family buildings. The proposed technology supports electrification strategies, load shifting, energy efficiency goals, and uses natural CO2 refrigerants with low global warming potential. Of particular interest is the packaged product’s potential for reducing equipment and design costs, specialized knowledge requirements, project timelines, and implementation complexity over equivalent custom, site-built products. A fully plug-and-play system eliminates the custom engineering and on-site construction, demonstrating what would be an invaluable industry transition. The onboard load shifting controls are also a novel addition in comparison to existing centralized heat pump water heater products and studies.
The skid-mounted, packaged product comprises multiple heat pump water heaters in series, storage and swing tanks, backup electric resistance elements, recirculation pumping, and all necessary controls and connection points. A primary and optional secondary skid can each serve up to 50 residential occupants with domestic hot water up to 160 °F and operate in ambient conditions down to -14 °F. The product supplies hot water for domestic use and currently does not have any design features for hydronic heating or exhaust capture for space cooling load offset, but could be of interest in future study. The product is well-suited to both retrofit and new construction applications although care needs to be given to electrical supply capacity, weight bearing structures, and other details which may be more costly in retrofit conditions. This is a brand new, first-of-its-kind product and has no to-date market adoption in California or otherwise.
The new packaged solution is being installed at the first two sites in the California Bay Area in early 2024, both of which will be monitored and evaluated for this study. Two new construction, multifamily buildings in San Francisco have already been selected and product production is underway. Currently, no M&V, performance assessment, or load shifting testing is planned or funded. The proposed study will add these important research features to the planned project, leveraging the planned installation for emerging technology research purposes. Monitoring instrumentation will be installed at the product level (at the HPWH rather than at residences or end-uses) at all relevant points including input power, ambient conditions, and hot/return/make-up water temperatures and flows. This M&V will allow for assessment of the system performance, load patterns, energy usage, and other key features necessary for informing market actors and programmatic design. All M&V data used in the analysis will be after HPWH commissioning and current project timelines suggest that commissioning will be completed before M&V instrumentation installation.
Since this is a new construction project, baseline energy usage will be calculated based on the observed load profiles and assumed code or representative baseline alterative (most likely central gas-fired). All project costs, including necessary electric service and panel upgrades, will be documented for evaluation of cost-effectiveness. Load shifting controls and abilities will also be tested either via manual tests or with load shift signals from the local utility. Whole building energy and demand will also be collected from utility metering to provide context to load shift capabilities and magnitudes. Monitoring data will be collected at intervals of 15-minutes or less and analyzed at the smallest interval necessary for accurate regression and energy cost analyses. Results will be presented for both raw, small intervals and consolidated at larger intervals for ease of visualization.
Although the technology will be studied in situ at new construction buildings, many of the findings will be extrapolated to existing building retrofit applications. Retrofit applications are critical since they comprise the vast majority of the market opportunity. Since load profiles are very consistent and predictable in the multifamily sector, energy, demand, and GHG savings can be determined for retrofit situations, assuming a code or market-representative baseline condition. Costs and feasibility differences between new construction and existing buildings will be evaluated, but since the product is a factory-built, packaged solution, similar cost-effectiveness and feasibility is expected. Other influential differences between new construction and retrofit applications and their impacts on cost-effectiveness, performance, or programs will be evaluated.
The study will build on existing research and initiatives for HPWH for the non-residential market, with a focus on the California market, policies, rate structures, efficiency and demand flexibility programs, and market barriers, and opportunities. The field study will evaluate product performance and energy, cost, and GHG impacts of the technology relative to baseline natural gas water heaters at one or two non-residential sites, as well as load flexibility capabilities in the context of CA rates, new SGIP offerings, and the new Total System Benefit (TSB) metric for EE programs. The market evaluation will build upon past research particularly by focusing on the packaged aspects of the product in comparison to custom site-built CO2 central heat pump water heaters. Study recommendations will focus on strategies for retrofit and new construction resource programs, workforce education and training programs, and how packaged solutions can address market barriers and challenges associated with current available CHPWH solutions.
Central heat pump water heaters (CHPWH) are essential to the reduction of energy usage and carbon emissions, addressing one of the largest energy-consuming end-uses in buildings. Packaged models show promise for reducing costs of these systems while increasing reliability and easing the hot water market transformation. Packaged CHPWHs can ease the installation and enable scaling of CHPWH adoption with fewer supply chain and installation barriers. Validation and enhancement of packaged CHPWH products is needed to encourage market adoption and find opportunities to maximize mutual benefits of the technology.
This report presents the findings of a field demonstration of packaged, carbon dioxide (CO2) CHPWHs installed at two new construction multifamily buildings. An average annual coefficient of performance of 2.9 was observed, resulting in reduced greenhouse gas emissions of 86 percent in comparison to a natural gas code baseline. Effective load shift controls displaced up to 52 percent of the energy out of peak time-of-use periods which reduced greenhouse gas emissions by 4.9 percent over a system without load shifting. Total system benefits and energy cost impacts are also presented.
Since these were among the first of this product type to be installed, the project team identified some opportunities for improvement which will yield even further benefits to building owners, utility programs, manufacturers, and installers. Recommendations include commissioning considerations of swing tank setpoints and recirculation return water balancing, attention to loads and efficiency in new construction buildings that may have partial occupancy residents move in, and active monitoring with fault detection diagnostics for maximizing impacts, quality installation, and persistence of savings. Future study should include demonstrations of packaged systems that minimize temperature maintenance loads through design variations and new program or rate structures that provide value to the building owner reflective of the benefits to the utilities and grid.
