Energy Retrofit Field Study and Best Practices in a Hot-Humid Climate J. McIlvaine, K. Sutherland, and E. Martin Building America Partnership for Improved Residential Construction March 2013 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. 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Martin BA-PIRC/Florida Solar Energy Center 1679 Clearlake Road Cocoa, FL 32922 NREL Technical Monitor: Stacey Rothgeb Prepared under Subcontract No. KNDJ-0-40339-00 March 2013 iii [This page left blank] iv Contents Acknowledgements ................................................................................................................................... xi List of Figures ............................................................................................................................................ vi List of Tables ............................................................................................................................................. vii Definitions ................................................................................................................................................. viii Executive Summary ................................................................................................................................... ix 1 Introduction ........................................................................................................................................... 1 1.1 Background ..........................................................................................................................3 1.2 Stakeholder Need .................................................................................................................4 1.3 Analysis Tools and Methods ................................................................................................4 2 Dataset Characterization and Retrofit Trends ................................................................................... 6 2.1 Dataset Overview .................................................................................................................6 2.2 Thermal Envelope Components ...........................................................................................7 2.2.1 Exterior Wall Construction and Insulation ..............................................................7 2.2.2 Exterior Wall Solar Absorptance .............................................................................8 2.2.3 Windows ..................................................................................................................9 2.2.4 Roof........................................................................................................................12 2.2.5 Ceiling Insulation ...................................................................................................14 2.3 Building Infiltration ...........................................................................................................16 2.4 Mechanical Space Conditioning Systems ..........................................................................19 2.4.1 Mechanical Equipment Efficiency, Pre-Retrofit ....................................................20 2.4.2 Mechanical Equipment Size ..................................................................................24 2.4.3 Air Handler Unit Location and Configuration .......................................................24 2.4.4 Duct Heat Transfer .................................................................................................28 2.4.5 Duct Airtightness ...................................................................................................29 2.4.6 Outside Air Ventilation ..........................................................................................31 2.4.7 Thermostats ............................................................................................................32 2.5 Domestic Hot Water ..........................................................................................................32 2.6 Appliances..........................................................................................................................33 2.7 Lighting and Ceiling Fans ..................................................................................................34 2.8 Conditioned Area Reductions ............................................................................................34 3 Whole-House Improvement and Cost Effectiveness ...................................................................... 36 3.1 HERS Index Improvement .................................................................................................36 3.2 Composition of Deep Energy Retrofit Improvement Packages .........................................38 3.3 Cost Effectiveness of Energy Retrofit Improvement Packages .........................................41 4 Gaps and Challenges ......................................................................................................................... 45 5 Best Practices ..................................................................................................................................... 46 6 Conclusions ........................................................................................................................................ 51 References ................................................................................................................................................. 52 Appendix A: 30% Energy Efficiency Solution Package ........................................................................ 54 Appendix B: Deep Energy Retrofit Packages ........................................................................................ 58 Appendix C: Draft Current Best Practices .............................................................................................. 65 Appendix D: Sarasota NSP Energy Conservation Standards .............................................................. 70 v List of Figures Figure 1. Mean HERS Index at pre-and post-retrofit by decade vintage ............................................... x Figure 2. U.S. Census Bureau historical housing starts by decade ...................................................... 1 Figure 3. U.S. Census Bureau regions ...................................................................................................... 1 Figure 4. Building America climate zone map ......................................................................................... 2 Figure 5. Study homes of typical character with ranch style floor plans, slab-on-grade foundations, concrete block exterior walls, low sloped roofs, and 8-ft ceiling heights ............... 3 Figure 6. Vintage of the 70 home dataset spanned 49 years .................................................................. 6 Figure 7. Conditioned floor area for the pre-retrofit dataset .................................................................. 7 Figure 8. Typical wall construction of light color paint on stucco finish over concrete block .......... 8 Figure 9. Typical awning-style window type ............................................................................................ 9 Figure 10. Pre-retrofit awning window in its most closed position is still slightly open as indicated by the pitch of the red line. ................................................................................................................ 12 Figure 11. Roof pitch plotted by vintage displays trend of older homes with shallower pitch n = 70 ...................................................................................................................................................