Lead Performer: Oak Ridge National Laboratory
Project Term: Ongoing
Funding Type: Direct Lab Funding

Heating, ventilation and air conditioning (HVAC), water heating, and other appliances represent more than half of the total energy used in U.S. residential and commercial buildings(EIA 2015 or 2017). Space conditioning is critical to household and business activities, indoor air quality, and comfort, and represents a vast opportunity for increasing building energy efficiency.


Heating, ventilation, and air conditioning (HVAC) is the largest energy end use in both residential and commercial buildings, at 38% and 31%, respectively. Oak Ridge National Laboratory’s (ORNL) early-stage research and development efforts aim to create next-generation, cost-effective, energy-efficient technologies that will enable energy savings through accelerated uptake of new, more energy-efficient HVAC products. To help achieve this goal, ORNL is conducting the following HVAC research and development:

  • Real-World Leak Assessments of Alternative Flammable Refrigerants: As natural and synthetic alternative refrigerants are sought, their performance and safety must be evaluated. Many alternative lower-GWP refrigerants carry varying risk of flammability. ORNL will conduct an experimental study to assess leaks of flammable refrigerants from various types of building equipment to update safety standards and contribute to a national and international research effort to enable greater use of these alternative refrigerants for different applications.
  • Novel Design for Compact Flooded Evaporators for Commercial Refrigeration Applications: ORNL is working on a novel compact design of flooded evaporators in commercial refrigeration applications. The larger size of the equipment is a disadvantage, so ORNL is using porous metal foam on the shell-side of a flooded evaporator to resolve issues of size.
  • Membranes AC: At present, membrane systems tend to be bulky and expensive to manufacture. ORNL will develop membrane based components of air conditioning systems that benefit from ultrasonically enhanced mass transfer.
  • Structured Carbon Nanorods for Intense Dehumidification: ORNL is working on a project involving dehumidification of atmospheric air using non-uniform electrostatic fields. This idea exploits the electrical properties of water, namely, the dipole moment. ORNL will synthesize carbon nanorods for controlled water sequestration using applied electric fields.
  • Solar Air Conditioning: ORNL will examine novel and hybrid heat pumps that will utilize solar, as well as natural gas or electricity to provide space conditioning and water heating in residential or commercial sectors. The use of solar energy will be the prime driver and the use of electricity or natural gas will be a secondary source of energy to fulfill the needs of a residential home.
  • Rapid Casted High Speed Centrifugal Compressor Impeller: ORNL is working on an alternative to using oil in smaller scale air conditioning systems: turbo-compressors. However, these systems tend to surge unexpectedly, so Active Flow Control is a promising technology that could downsize to smaller scale air conditioning without diminishing the performance of the turbo-compressor.
  • Design and Optimization for New Refrigerant Blends: ORNL will extend the ORNL Heat Pump Design Model to perform system-level evaluations and optimizations of newly identified fluids for specific applications. Additionally, this project will establish a public-domain, online knowledgebase for equipment design and optimization, and represent heat transfer and pressure drop characteristics of low-GWP alternative refrigerant blends using the hardware-based equipment design model.
  • Peel and Stick Refrigerant Sensor for Flammable Refrigerant Detection: The focus of this research is to develop a low-cost, integrated sensor system to detect NH3, CFCs, and HCFCs, as this is critical to address the health, safety and environmental issues associated with current and emerging low-GWP refrigerants. Currently, there is a lack of low-cost sensors for direct and continuous monitoring of refrigerant leakage.
  • Separate Sensible and Latent Cooling AC System: Separate sensible and latent cooling systems offer significant increases in overall performance of cooling/dehumidification systems compared to conventional vapor-compression air-conditioning systems. Key to the energy efficiency of such systems is the performance of the heat and mass exchangers that provide sensible cooling and dehumidification. Metal foals have emerged as a potential material for advanced heat exchangers in air-cooling systems. This project will use metal foams for air-side heat and mass transfer in air-conditioning heat exchangers.
  • Low-Cost Ground Heat Exchangers for Residential Applications: ORNL will develop an innovative low-cost Ground Heat Exchanger for residential applications, and evaluate the feasibility of a compact multi-source thermal battery for residential geothermal heat pump applications.
  • Commercial Absorption Heat Pump: ORNL will conduct research and development to evaluate the technical and commercial viability of a commercial heat pump water heater fired by natural gas to accomplish improved efficiency levels while using low GWP refrigerants.
  • Data Analysis from Ground Source Heat Pump (GSHP) Demonstration Projects: Analysis of the costs and benefits of Recovery Act GSHP projects.
  • Air-Source Integrated Heat Pump: Development and promotion of an Advanced Air-Source Integrated Heat Pump (AS-IHP) with energy savings equal to or greater than 50% versus minimum efficiency systems.
  • Advanced Ground Source Heat Pump (GSHP) Technology for Very-Low-Energy Buildings: Acceleration of GSHP deployment by developing and identifying new technologies that reduce cost and/or improve performance. This is in addition to an exchange of best practices between the United States and China, which can lead to improved efficiency and lower costs.
  • Next Generation Rooftop Unit: Development of a rooftop air conditioning unit (RTU) providing cooling capacity above 150,000 Btu/hr with an Integrated Energy Efficiency Ratio (IEER) of 22 (at the AHRI 340/360 rating conditions).
  • Split-System Cold Climate Heat Pump: Development of a split-system, cold climate heat pump (CCHP) that provides a nominal heating capacity of 36,000 Btu/hr (3 tons) with a COP of 4.0 at the 47oF ambient temperature standard rating condition.
  • Commercial Integrated Heat Pump: The objective of this project is to develop an air-source integrated heat pump for cooling-dominated commercial buildings with significant water heating needs (e.g., fast food, restaurants, laundries) with cooling COP> 5.5 and an estimated payback period is less than five years.
  • International HVAC&R Research Collaboration through IEA and IRR: This is a collaborative task with the International Energy Agency (IEA) Heat Pump Technologies program and the International Institute of Refrigeration (IRR) to engage with participants in technology development of core interest to BTO. As the U.S. is a world leader in scientific research and engineering, it is valuable to provide insight on the latest HVAC&R and water heater technology developments directed toward improving building equipment energy efficiency around the world.

Water Heating

Water heating accounts for 13% of primary energy consumption in residential buildings and 4% in commercial buildings. The commercial building energy savings opportunity is larger and more easily accessible than it would appear because water heating energy use is concentrated in only a few building types (e.g., fast food, restaurants, laundries, hotels, hospitals) with large requirements. In FY18, ORNL’s water heater early-stage research and development (R&D) portfolio has the potential to greatly improve energy savings through the following projects:

  • Membrane-based Water Heater: A new sorption cycle, the semi-open sorption cycle, has been invented that promised dramatically lower costs by operating at atmospheric pressure, eliminating the evaporator component, and utilizing non-corrosive ionic liquid compatible with inexpensive polymer components.
  • Residential Absorption Heat Pump Water Heater: The project objective is to develop an ionic liquid-based residential absorption heat pump water system with an energy factor great than 1.0 at an installed cost low enough to enable widespread market penetration in the U.S.
  • Commercial Absorption Heat Pump Water Heater: ORNL will conduct research and development to evaluate the technical and commercial viability of a commercial heat pump water heater fired by natural gas to accomplish improved efficiency levels using low GWP refrigerants.
  • CO2 Heat Pump Water Heater: The objective is to develop a CO2 heat pump water heater (HPWH) that meets ENERGY STAR® standards for HPWHs at an installed cost that will enable widespread acceptance in the U.S. residential market.
  • Residential Adsorption Water Heater: The project objective is to develop an adsorption heat pump water heater that will demonstrate an energy factor greater than 1.0 and at an installed cost low enough to enable widespread residential market adoption.
  • Max Tech Electric Heat Pump Water Heater with Lower GWP Halogenated Refrigerant: ORNL will work to evaluate different cycle configurations, and refrigerant options of an electric heat pump water heater and achieve maximum market-viable energy efficiency.
  • Commercial CO2 Electric Heat Pump Water Heater: Residential HPWHs based on CO2 have not been successful in U.S. markets thus far, primarily due to cost. The objective of this project is to evaluate cycle configurations and system designs to determine the best path forward for cost-effective CO2-based electric HPWHs targeted for commercial water heating applications, where delivery of higher temperature water (an inherent advantage of C02) is valued in the market.


Building equipment efficiency plays an important role in achieving US energy security. According to the most recent Energy Information Administration (EIA) estimates, residential and commercial buildings will consume 38.22 quads or 37.6% the total US primary energy consumption in the year 2030, continuing to exceed industrial and transportation energy consumption. In FY18, Oak Ridge National Laboratory (ORNL) will focus on early-stage research in Appliances R&D. In the residential space, BTO primarily focuses on refrigerator/freezers and clothes dryers, which have the most opportunity for energy savings. The commercial building focus is on refrigeration systems as refrigerants research is becoming critical to advancing energy savings in the industry. ORNL’s ongoing R&D projects related to appliances include:

  • Thermoelectric Clothes Dryer: ORNL will develop a clothes dryer with significant energy savings, but reduced cost premium compared to state-of-the-art heat pump-based dryers.
  • Ultrasonic Clothes Dryer: ORNL will develop and commercialize a novel clothes dryer based on the innovative approach to mechanically extract water from fabric using high-frequency vibration generated by piezoelectric transducers.
  • Radiation Defrosting: Current defrost practices, including the use of electric resistance heaters and hot gas, have several disadvantages due to their adverse impact on system efficiency, additional power requirements and complicated control systems. Due to these disadvantages, utilization of ultraviolet (UV) and microwave radiation is proposed as an alternative solution due to advantages in energy efficiency and process control. ORNL has test facilities to understand the interaction of radiation with humid air, bare metal surfaces, and the frost.
  • Electrochemical Compressor (ECC) Refrigerator: ORNL will develop a domestic refrigerator using an innovative electrochemical compressor (ECC). Unlike mechanical compressors, electrochemical compressors don’t have any moving parts and thus are not subject to volumetric efficiency loss due to residual volume, and isentropic efficiency loss due to internal heating, motor efficiency and friction loss.
  • Novel Commercial Refrigeration: ORNL will use a pressure exchanger to reduce the expansion losses in commercial refrigeration systems. A pressure exchanger allows the pressure of a high-pressure stream to be transferred to a low-pressure stream and vice-versa.
  • Heat Pump Clothes Dryer: The objective of this project is the design and develop a heat pump clothes dryer that has the potential of lowering the energy consumption by 60% as compared with conventional resistance heaters.
  • Magnetocaloric Refrigerator: ORNL will develop the world’s first magnetocaloric refrigerator that could change the concept of residential refrigeration technology.
  • High-Efficiency, Low-Emission Refrigeration System: The objective of this project is to develop a supermarket refrigeration system that reduces lifetime greenhouse gas emissions by 75% and has 25% to 30% lower energy consumption than existing supermarket refrigeration systems.
  • Low-GWP Refrigerants for Refrigeration Systems: The objective of this project is to optimize the blend of refrigerants to result in an alternative refrigerant that satisfies all safety requirements and when dropped into existing supermarket refrigeration hardware in place of R-404A maximizes GWP reduction and energy efficiency.


DOE Technology Manager: Tony Bouza
Lead Performer: Ayyoub M. Momen, Oak Ridge National Laboratory