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Zone Pressure Diagnostics

This standardized curriculum covers zone pressure diagnostics, including strengths, limitations, and practical applications. Learn how to conduct and interpret zone pressure tests for energy efficiency improvements. Includes hands-on activities to prioritize air sealing and assess air barrier locations. 8 Relevant

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Zone Pressure Diagnostics

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  1. Zone Pressure Diagnostics WEATHERIZATION ENERGY AUDITOR SINGLE FAMILY WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012

  2. Learning Objectives Zone Pressure diagnostics By attending this session, participants will be able to: • Demonstrate the strengths and limitations of zone pressure diagnostics (ZPD). • Assess when to use zone pressure diagnostics. • Demonstrate the use of ZPD charts.

  3. Zone Pressure Diagnostics #1 Zone Pressure diagnostics Conduct zone pressure diagnostics and interpret results to determine: • Location and effectiveness of the air barrier. • Alignment of air barrier and thermal boundary. • Leakage between zones. Photos courtesy of PA WTC Photo courtesy of PA Weatherization Training Center

  4. Necessary Equipment Zone Pressure diagnostics Photos courtesy of the U.S. Department of Energy

  5. Determine relative leakiness. Prioritize air sealing activities. Evaluate completed air sealing measures. Practical Applications Zone Pressure diagnostics

  6. Relative Leakiness Zone Pressure diagnostics 1850 CFM50 Pressure houseto attic = 37Pa Pressure attic toexterior must be 13Pa (50Pa – 37Pa = 13Pa) Q: What doesthis tell us? 50Pa 37Pa ? Pa Graphic developed for the U.S. DOE WAP Standardized Curricula

  7. Zone Pressures Relative Size of Leaks Ratio of Pressure to Leakage Zone Pressure diagnostics TO TO

  8. Probing Cavities Zone Pressure diagnostics Let’s put a probe into the cellar. What does25Pa mean? What if we stick a probe into the first floor ceiling cavity and read 41Pa? 50Pa 37Pa 25Pa 41Pa • Graphic developed for the U.S. DOE WAP Standardized Curricula

  9. Changing Pressures Zone Pressure diagnostics If we open the cellar door to the house and put a probe into the attic we might find the attic 37Pa has dropped to25Pa. The pressure between the house and basement will now be zero. Why? 50Pa 25Pa 0Pa Graphic developed for the U.S. DOE WAP Standardized Curricula

  10. Simple Zone Pressure Diagnostics #1 Zone Pressure diagnostics Pressure difference of attic with reference to the house should be close to -50 Pa. ΔP = -50 Pa Blower Door Graphic developed for the U.S. DOE WAP Standardized Curricula

  11. Simple Zone Pressure Diagnostics #2 Zone Pressure diagnostics Pressure difference of interior wall with reference to the house should be close to 0 Pa. ΔP = 0 Pa Blower Door Graphic developed for the U.S. DOE WAP Standardized Curricula

  12. Where Is the Air Barrier? #1 Zone Pressure diagnostics Cape Cod1½ Story House • Graphic developed for the U.S. DOE WAP Standardized Curricula

  13. Where Is the Air Barrier? #2 Zone Pressure diagnostics Pressure difference of the floor cavity with reference to the house should be 0 Pa. But, is it? 48 Graphic developed for the U.S. DOE WAP Standardized Curricula

  14. Where Is the Air Barrier? #3 Zone Pressure diagnostics Unsealed/Uninsulated Two-story balloon-framed house with one-story addition and unheated porch over unconditioned basement Graphic developed for the U.S. DOE WAP Standardized Curricula

  15. Where Is the Air Barrier? #4 Zone Pressure diagnostics Sealed/Insulated Air-sealed/Insulated with air barrier and insulation in alignment Graphic developed for the U.S. DOE WAP Standardized Curricula

  16. Can We Size The Holes? Zone Pressure diagnostics Pressure is gradually reduced by each layer of wall or ceiling between inside and outside. Collecting CFM50 and pressure across each configuration lets us calculate hole size in each surface. 50Pa 25Pa 0Pa Graphic developed for the U.S. DOE WAP Standardized Curricula

  17. Here is what we know Zone Pressure diagnostics 1850 CFM50 2200 CFM50 50Pa 25Pa 50Pa 50Pa 25Pa 0Pa Basement door closed Basement door open • Graphics developed for the U.S. DOE WAP Standardized Curricula

  18. Open A Door – Zone To Main Body Zone Pressure diagnostics 25Pa 1850 2200 350 350 2.76 966 97 sq” 350 2.76 966 97 sq” 616 CFM50 350 1.76

  19. What Do The Results Mean? Zone Pressure diagnostics H/Z 350 x 2.76 = 966 CFM50 = 96.6 sq” of hole in the floor Z/O 350 x 2.76 = 966 CFM50 = 96.6 sq” hole in basement walls T/P 350 x 1.76 = 616 CFM50 is attributable to the path 50Pa 50Pa Graphic developed for the U.S. DOE WAP Standardized Curricula

  20. Open A Door – Zone To Outside Zone Pressure diagnostics

  21. No Door on the Zone? Zone Pressure diagnostics At 1850 CFM50, house to attic pressure = 37Pa. Open attic hatch enough to create at least 6Pachange. Bring the blower door back to 50Pa. CFM50 is now 2500 House to attic pressure is now 20Pa. 50Pa 20Pa Graphic developed for the U.S. DOE WAP Standardized Curricula

  22. Flow Method: Hole – Zone To House #1 Zone Pressure diagnostics

  23. Flow Method: Hole – Zone To House #2 Zone Pressure diagnostics 1850 37Pa 2500 20Pa 650 1.38 884

  24. Flow Method: Hole – Zone To Outside Zone Pressure diagnostics

  25. What Did We Learn Overall? Zone Pressure diagnostics Of 1850 CFM50: Through attic ≈ 900 Through basement ≈ 600 Walls (remainder) ≈ 350 50Pa Graphic developed for the U.S. DOE WAP Standardized Curricula

  26. Checking Air Sealing Zone Pressure diagnostics How about a garage? Any space that will accept a probe can be checked for pressure. ZPD requires being able to change the pressure over the surface to determine hole size. 48Pa 50Pa 2Pa Graphic developed for the U.S. DOE WAP Standardized Curricula

  27. Limitations Zone Pressure diagnostics • Not great for excessively leaky buildings • Requires being able to change the pressure over the tested surface to determine hole size • Not great in windy conditions • Time consuming

  28. Practice!

  29. Open A Door – Zone To Main Body Zone Pressure diagnostics 40Pa 2050 2550 500 500 500 500

  30. Open A Door – Zone To Main Body Zone Pressure diagnostics 40Pa 2050 2550 500 0.63 500 31.5 sq” 315 500 1.54 77 sq” 770 500 270 CFM50 0.54

  31. Flow Method: Hole – Zone To House Zone Pressure diagnostics 1200 45Pa 1850 18Pa 650

  32. Flow Method: Hole – Zone To House Zone Pressure diagnostics 1200 45Pa 1850 18Pa 650 0.43 280

  33. Summary Zone Pressure diagnostics • ZPD can help you determine the relative leakiness of a home, prioritize air sealing activities, and evaluate completed air sealing measures. • ZPD requires a computer or charts to do the calculations. • The calculations can be time consuming, so use ZPD only when needed to prioritize or verify critical air sealing activities. • ZPD does not work well in extremely leaky homes or when it’s very windy. • ZPD requires being able to change the pressure over the tested surface to determine hole size.

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