Building Technologies Office Energy Savings Potential and Research, Development, & Demonstration Opportunities for Residential Building Heating, Ventilation, and Air Conditioning Systems October 2012 NOTICE This 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, nor any of their contractors, subcontractors, or 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, contractor or subcontractor 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. Available electronically at http://www.osti.gov/home/ i Energy Savings Potential and RD&D Opportunities for Residential Building HVAC Systems Prepared for: U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Building Technologies Office http://www.eere.energy.gov/buildings Prepared by: Navigant Consulting, Inc. 77 South Bedford Street, Suite 400 Burlington, MA 01803 William Goetzler Robert Zogg Jim Young Justin Schmidt September 30, 2012 ii Table of Contents Table of Contents ........................................................................................................................... iii List of Acronyms ........................................................................................................................... vi Executive Summary ....................................................................................................................... ix 1 Introduction ............................................................................................................................. 1 1.1 Report Organization ......................................................................................................... 1 1.2 Background ...................................................................................................................... 1 1.2.1 Breakdown of Residential HVAC Energy Consumption ......................................... 2 2 Technology Selection and Screening Processes ..................................................................... 6 2.1 Develop Initial List of Technology Options .................................................................... 7 2.2 Develop the Initial Screening Criteria / Identify Technology Options for Preliminary Analyses and Separate Early-Stage Technology Options ........................................................... 8 2.2.1 Initial Screening Process ........................................................................................... 8 2.2.2 Identification of Early-Stage Technology Options ................................................... 9 2.2.3 Grouping of Technology Options for Preliminary Analysis ..................................... 9 2.3 Perform Preliminary Analyses for the Selected Technology Options ........................... 11 2.3.1 Overview of the Preliminary Analysis .................................................................... 11 2.3.2 Estimating Technical Energy Savings Potential ..................................................... 11 2.4 Develop Scoring Criteria to Evaluate the Selected Technology Options ...................... 13 2.5 Select Priority Technology Options and Perform In-Depth Analyses ........................... 15 3 Summary of the 19 Priority Technology Options ................................................................. 16 3.1 Advanced Component Technology Options .................................................................. 18 3.2 Alternative Heating and Cooling Technology Options .................................................. 18 3.3 Advanced Heat-Pump Technology Options ................................................................... 19 3.4 High-Performance System Design and Restoration Technology Options ..................... 20 3.5 Intelligent Controls and Diagnostic Technology Options .............................................. 21 4 Summary of the 10 Early-Stage Technology Options .......................................................... 23 5 Conclusions ........................................................................................................................... 24 5.1 Summary of the Technology Screening Process ............................................................ 24 5.2 Observations on the 19 Priority Technology Options .................................................... 25 5.2.1 Technology Categories ........................................................................................... 25 5.2.2 Peak-Demand Reduction and other Non-Energy Benefits ..................................... 26 5.2.3 Technical Energy Savings Potential ....................................................................... 27 5.2.4 Cost and Complexity............................................................................................... 29 5.3 Comparison with 2011 Commercial HVAC Study ........................................................ 30 5.4 Summary of Recommended RD&D Initiatives for Both Residential and Commercial HVAC ....................................................................................................................................... 37 5.4.1 Summary of Recommended DOE-Led Initiatives .................................................. 38 5.4.2 Summary of Recommended Manufacturer-Led Initiatives .................................... 44 5.4.3 Summary of Recommended Industry Organization-Led Initiatives ....................... 45 5.4.4 Summary of Recommended Utility Initiatives ....................................................... 47 Appendix A List of the Initial 135 Technology Options ......................................................... 49 iii Appendix B List of Resources Used in Literature Search ....................................................... 52 Appendix C Abridged Analyses of the 10 Early-Stage Technology Options ......................... 56 C.1 Active Modular Phytoremediation System .................................................................... 57 C.2 Advanced-Membrane Heat Pump .................................................................................. 59 C.3 Air-Bearing Heat Exchanger .......................................................................................... 61 C.4 Bernoulli Heat Pump ...................................................................................................... 63 C.5 Binary-Fluid Ejector ....................................................................................................... 65 C.6 Co-Fluid Vapor Compression ........................................................................................ 66 C.7 Metal-Foam Heat Exchangers ........................................................................................ 68 C.8 Self-Cleaning Furnace Heat Exchanger ......................................................................... 70 C.9 Thermoelastic Cooling System ...................................................................................... 72 C.10 Turbo-Compressor-Condenser-Expander ................................................................... 74 Appendix D Preliminary Analyses .......................................................................................... 76 D.1 Advanced Defrost Methods for Heat Pumps.................................................................. 77 D.2 Advanced Evaporative Coolers ...................................................................................... 79 D.3 Airflow-Optimizing System ........................................................................................... 84 D.4 Air-Ground Heat Exchanger .......................................................................................... 86 D.5 Chilled-Beam Radiant Cooling ...................................................................................... 89 D.6 District Heating and Cooling ......................................................................................... 91 D.7 Ductwork in the Conditioned Space............................................................................... 94 D.8 Evaporative Roof Cooling .............................................................................................. 97 D.9 Evaporatively Cooled Condensers ............................................................................... 100 D.10 Hot-Dry Air Conditioners ......................................................................................... 103 D.11 Improved Duct Systems............................................................................................ 106 D.12 Liquid-Desiccant Air Conditioner ............................................................................ 109 D.13 Magnetic Cooling System ........................................................................................ 113 D.14 Microchannel Heat Exchanger ................................................................................. 117 D.15 Mixed-Mode Conditioning ....................................................................................... 119 D.16 Night Sky Radiant Cooling....................................................................................... 121 D.17 Nighttime Ventilation Cooling ................................................................................. 124 D.18 Quality Installation ................................................................................................... 127 D.19 Seasonal Thermal Energy Storage ............................................................................ 130 D.20 Smaller Centrifugal Compressors ............................................................................. 133 D.21 Smart Ventilation Systems ....................................................................................... 136 D.22 Swimming-Pool Heat Sink ....................................................................................... 140 D.23 Variable-Stroke Compressor .................................................................................... 142 Appendix E Technical Energy Savings Potential of the 42 Technology Options ................. 145 Appendix F Scoring Results for the 42 Technology Options ............................................... 146 Appendix G In-Depth Analyses of the 19 Priority Technology Options............................... 148 G.1 Advanced Component Technology Options ................................................................ 150 G.2 Brushless Direct-Current Motors ................................................................................. 150 G.3 Smart Refrigerant Distributors ..................................................................................... 154 G.4 Alternative Heating and Cooling Technology Options ................................................ 161 G.5 Gas-Fired Absorption Heat Pumps .............................................................................. 161 G.6 Thermoelectric Cooling System ................................................................................... 169 iv G.7 Thermoelectrically Enhanced Subcoolers .................................................................... 175 G.8 Thermotunneling Cooling System ............................................................................... 182 G.9 Advanced Heat Pump Technology Options ................................................................. 187 G.10 Ductless Multi-Split System ..................................................................................... 187 G.11 Gas Engine-Driven Heat Pump ................................................................................ 194 G.12 Geothermal Heat Pump ............................................................................................ 203 G.13 Heat Pump for Cold Climates ................................................................................... 213 G.14 Hybrid Geothermal Heat Pump ................................................................................ 219 G.15 Integrated Heat Pump ............................................................................................... 225 G.16 High-Performance System Design and Restoration Technology Options ............... 230 G.17 Aerosol Duct Sealing ................................................................................................ 230 G.18 Regular Maintenance ................................................................................................ 235 G.19 Retrocommissioning ................................................................................................. 240 G.20 Intelligent Controls and Diagnostic Technology Options ........................................ 245 G.21 Central A/C and Heat Pump Fault Detection and Diagnostics ................................. 245 G.22 Home Energy Management System ......................................................................... 251 G.23 Learning Thermostats ............................................................................................... 256 G.24 Smart Ceiling-Fan Controls ...................................................................................... 261 v List of Acronyms ABHX Air-Beating Heat Exchanger A/C or AC Air Conditioning or Air Conditioner ACEEE American Council for an Energy-Efficient Economy ACHR Air-Conditioning, Heating, and Refrigeration AHRI Air-Conditioning, Heating, and Refrigeration Institute AMP Active Modular Phytoremediation ARPA-E Advanced Research Projects Agency - Energy ARTI Air-Conditioning and Refrigeration Technology Institute ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers ASPE American Society of Plumbing Engineers BAIHP Building America Industrialized Housing Partnership BEETIT Building Energy Efficiency through Innovative Thermodevices BFE Binary-Fluid Ejector BLDC Brushless Direct Current BTP U.S. Department of Energy, Building Technologies Btu British thermal unit Btuh British thermal unit hour CASE Center for Architecture, Science and Ecology CAV Constant Air Volume CBEA Commercial Building Energy Alliance CEC California Energy Commission CO₂ Carbon Dioxide COP Coefficient of Performance DCV Demand-Controlled Ventilation DEVap A/C Desiccant-Assisted Evaporative Air Conditioner DMS Ductless Multi-Split DOAS Dedicated Outdoor Air System DOD U.S. Department of Defense DOE U.S. Department of Energy DTU Technical University of Denmark DX Direct-Expansion eCOP Effective Coefficient of Performance EE&T Energy Efficiency and Technology EERE U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy EIA U.S. Department of Energy, Energy Information Administration EMS Energy Management System EPA U.S. Environmental Protection Agency ERV Energy Recovery Ventilator ES Executive Summary vi FDD Fault Detection and Diagnostics FEMP Federal Energy Management Program ft Foot GAHP Gas-Fired Absorption Heat Pump GAX Generator-Absorber Heat Exchange GE General Electric GEHP Gas-Engine-Driven Heat Pump GHP Geothermal Heat Pump GWP Global-Warming Potential HCFC Hydrochlorofluorocarbon HDAC Hot-Dry Air Conditioner HFC Hydrofluorocarbon HRV Heat Recovery Ventilator HSPF Heating Seasonal Performance Factor HT Heat Transfer HVAC Heating, Ventilation, and Air Conditioning HX Heat Exchanger IAQ Indoor Air Quality IDEC Indirect/Direct Evaporative Cooler IEA International Energy Agency IHP Integrated Heat Pump IIR International Institute for Refrigeration ITC Isothermal Turbocompressor JARN Japanese Air-Conditioning, Heating, and Refrigeration News LBNL Lawrence Berkeley National Laboratory LDAC Liquid-Desiccant Air Conditioner mCHP Micro-Combined Heat and Power MCHX Microchannel Heat Exchanger NEEA Northwest Energy Efficiency Alliance NEH Net Zero Energy Home NIST National Institute of Standards and Technology NiTi Nitinol NSRC Night Sky Radiant Cooling NYSERDA New York State Energy Research and Development Authority OA Outdoor Air ODP Ozone Depletion Potential OEM Original Equipment Manufacturer ORNL Oak Ridge National Laboratory PATH Partnership for Advanced Technology in Housing PCT Patent Cooperation Treaty PIER Public Interest Energy Research PNNL Pacific Northwest National Laboratory PSAC II Public Safety Answering Center II vii PUMF Public Use Microdata File Quad Quadrillion Btu R&D Research and Development RCx Retrocommissioning RD&D Research, Development, and Demonstration RECS Residential Energy Consumption Survey rpm Revolutions per Minute RTU Rooftop Unit SEDS State Energy Data System SEER Seasonal Energy Efficiency Ratio SMA Smart-Memory Alloys sq. ft. Square Foot SR Switched-Reluctance SWEEP Southwest Energy Efficiency Program TCCE Turbo-Compressor-Condenser-Expander TE Thermoelectric TES Thermal Energy Storage TIM Thermal Interference Material TSD Technical Support Document UMD University of Maryland US United States VOC Volatile Organic Compounds VRF Variable Refrigerant Flow VRV Variable Refrigerant Volume W Watt WCEC Western Cooling Efficiency Center ZT Dimensionless figure of merit for thermoelectric materials viii Executive Summary The U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Program (BTP) commissioned this characterization and technology assessment of heating, ventilation, and air-conditioning (HVAC) systems for residential buildings. The main objectives of this study were the following:  Identify a wide range of technology options in varying stages of technology development that could reduce residential HVAC energy consumption  Prioritize and analyze selected technology options, including technical energy savings potential, applicability to various building or HVAC equipment types, non-energy benefits, and barriers to market adoption  Recommend potential research, development, and demonstration (RD&D) initiatives that would support further development of the most promising technology options, based on technical energy savings potential, fit with DOE BTP’s mission, and cost and complexity. To develop the priority list of technology options and recommended RD&D initiatives for this study, we followed a technology selection, screening, and assessment process. We first generated a comprehensive list of 135 technology options (listed in Appendix A) from a variety of sources including: manufacturers’ websites, industry publications, government organizations, university research, and industry experts. Through this initial screening, we cataloged general information about each technology such as its potential energy efficiency impact and potential applicability to various residential HVAC systems. After examining the initial list, we identified 52 technology options that demonstrated the highest potential to reduce HVAC energy consumption in residential buildings, but that have not yet been adopted widely by the market. After our initial screen, we separated technology options for which there was a paucity of publicly available information, because they are still in the early stages of research and development (R&D). Because we were unable to find energy and cost savings estimates for these technology options, we identified 10 technology options that we could not evaluate against the other technology options. Thus, we did not prioritize them, but instead made separate recommendations for DOE, described in Section 5.4.1. Table ES-1 presents the 10 early-stage technology options that we identified. ix