Measure Guideline: Supplemental Dehumidification in Warm-Humid Climates Armin Rudd Building Science Corporation October 2014 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, subcontractors, or affiliated partners 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. Available electronically at http://www.osti.gov/scitech Available for a processing fee to U.S. Department of Energy and its contractors, in paper, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 phone: 865.576.8401 fax: 865.576.5728 email: mailto:[email protected] Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone: 800.553.6847 fax: 703.605.6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm Measure Guideline: Supplemental Dehumidification in Warm-Humid Climates Prepared for: The National Renewable Energy Laboratory On behalf of the U.S. Department of Energy’s Building America Program Office of Energy Efficiency and Renewable Energy 15013 Denver West Parkway Golden, CO 80401 NREL Contract No. DE-AC36-08GO28308 Prepared by: Armin Rudd Building Science Consortium 30 Forest Street Somerville, MA 02143 NREL Technical Monitor: Cheryn Metzger Prepared under Subcontract No. KNDJ-0-40337-03 October 2014 iii The work presented in this report does not represent performance of any product relative to regulated minimum efficiency requirements. The laboratory and/or field sites used for this work are not certified rating test facilities. The conditions and methods under which products were characterized for this work differ from standard rating conditions, as described. Because the methods and conditions differ, the reported results are not comparable to rated product performance and should only be used to estimate performance under the measured conditions. iv Contents List of Figures ............................................................................................................................................ vi List of Tables ............................................................................................................................................. vii Definitions ................................................................................................................................................. viii Abstract ....................................................................................................................................................... ix Acknowledgments ...................................................................................................................................... x Progression Summary ............................................................................................................................... xi 1 Introduction ........................................................................................................................................... 1 2 Decision-Making Criteria ..................................................................................................................... 3 2.1 Cost and Performance ..........................................................................................................3 2.2 Risk Identification ................................................................................................................4 3 Technical Description .......................................................................................................................... 5 3.1 System Interaction ...............................................................................................................5 4 Measure Implementation ..................................................................................................................... 6 4.1 Install Procedure ..................................................................................................................6 4.1.1 Enhanced Cooling Option (Lower Evaporator Airflow and Overcooling) .............6 4.1.2 Standalone Dehumidifier Option .............................................................................8 4.1.3 Integrated Ducted Dehumidifier Option (Integrated With the Central System) ....13 4.1.4 Subcooling Reheat Option (With Enhanced Cooling Option) ...............................19 4.1.5 Full Condensing and Subcooling Reheat Option ...................................................21 4.1.6 Direct Expansion Condenser-Regenerated Desiccant Dehumidifier Option .........25 4.1.7 Gas-Regenerated Desiccant Dehumidifier Option .................................................27 5 Verification Procedures and Tests ................................................................................................... 30 References ................................................................................................................................................. 32 v List of Figures Figure 1. IECC climate zone map showing warm-humid line generally extending from Wilmington, North Carolina to Dallas, Texas .......................................................................................................... 3 Figure 2. Standalone dehumidifier option, in one-story home closet application, with louvered closet door, near central system return air grille .............................................................................. 9 Figure 3. Standalone dehumidifier option, in two-story home closet application, with louvered closet door, near central system return air grille ............................................................................ 10 Figure 4. Standalone ducted dehumidifier option, in unvented crawlspace application .................. 11 Figure 5. Standalone ducted dehumidifier, in basement application .................................................. 12 Figure 6. Integrated ducted dehumidifier integrated with central system, in one-story home closet application ........................................................................................................................................... 14 Figure 7. Integrated ducted dehumidifier integrated with central system, in unvented attic application ........................................................................................................................................... 15 Figure 8. Integrated ducted dehumidifier installation ........................................................................... 16 Figure 9. Integrated ducted dehumidifier integrated with the central system, in an unvented crawlspace application ...................................................................................................................... 17 Figure 10. Integrated ducted dehumidifier integrated with central system, in basement application18 Figure 11. Enhanced cooling with subcooling reheat option ............................................................... 20 Figure 12. Photo of subcooling reheat coil ............................................................................................ 20 Figure 13. Full Condensing and subcooling reheat option, with modulating hot gas reheat, supplying dry air at room neutral temperature ............................................................................... 22 Figure 14. Outdoor (left) and indoor (right) units of the full condensing and subcooling reheat option; the outdoor unit shows the three refrigerant connections to the indoor unit; the indoor unit shows the condenser reheat coil at the top ............................................................................. 23 Figure 15. Controller with detailed settings and on-board diagnostics for the full condensing and subcooling reheat option with modulating hot gas reheat ............................................................ 24 Figure 16. DX condenser-regenerated desiccant dehumidifier option ............................................... 26 Figure 17. Gas-regenerated desiccant dehumidifier option ................................................................. 28 Unless otherwise noted, all figures were created by BSC. vi List of Tables Table 1. First-Cost Estimates for Supplemental Dehumidification Systems ........................................ 4 Table 2. Minimum Supplemental Dehumidification Capacity Guideline ............................................... 5 Table 3. Humidity Control Performance of the Enhanced Cooling Option, With the Lower Airflow and 2°F Overcooling, Compared to the Conventional System ........................................................ 7 Table 4. Performance Criteria for ENERGY STAR-Qualified Dehumidifiers ........................................