NFRC vs. PHI vs. PHIUS Window Certification for the US

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A review of the three window certifications now available for window manufacturers on the US market. First issued in July, 2013 and updated on June 28th, 2015. This builds on a previous comparison I've done reviewing differences in testing protocols by PHI and NFRC.

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NFRC vs. PHI vs. PHIUS Window Certification for the US

  1. 1. NFRC vs. PHI vs. PHIUS Window Certification The full fruit basket? Bronwyn Barry, Assoc. AIA., CPHD Design Director - One Sky Homes July 11, 2013 *Edited: June 29, 2015
  2. 2. Three window rating systems now on US market: Passive House Institute (PHI): • International • Climate-Specific Performance Req’d* • Simulation only Passive House Institute, US (PHIUS): • US – based • No Min. Performance Req’d • Simulation only National Fenestration Rating Council (NFRC): • North America based • No minimum standards • Simulation and Product Test Req’d
  3. 3. NFRC’s certification criteria: Simulation: 1. Uwindow (required) 2. SHGC (required) 3. Air Leakage (optional) 4. Visible Light Transmittance (optional) (No Min. Performance Req’d.) Verification: 1. Destructive test of window sample 2. Factory inspection Image from NFRC website: http://nfrc.org/fenestrationfacts.aspx
  4. 4. PHI’s Certification Criteria: 3 Simulation Min. Requirements: 1. *Climate Specific (Was: Uw </= 0.8 W/m2 K (0.14 BTU/hrft2 F or 6.7 hrft2 F/BTU) 2. Uw installed </= 0.85 W/m2 K 3. fRsi </= 0.7 (Varies for other transparent components, including curtain walls, roof domes and skylights. See document: Certification criteria and calculation regulations Passive House Suitable Transparent Components: http://www.passiv.de/downloads/03_certification_criteria_tr ansparent_components_en.pdf) Image from PHI component database: http://www.passiv.de/komponentendatenbank/files/pdf/zertifikate/zd_northwin_vision_en.pdf
  5. 5. Simulation: 1. Uwindow (required) 2. SHGC (required) 3. Air Leakage (optional) 4. Visible Light Transmittance (optional) (No Min. Performance Req’d.) Image from PHIUS info document for window manufacturers – Graham Wright PHIUS’s Data Certification Program:
  6. 6. How NFRC calc’s U-window: (Ucog*Acog) + (Uf*Af) + (Uedge*Aedge) Aw Uw = Ucog Acog Uf Af Ucog = U-value glass Acog = Area glass Uf = U-value frame Af = Area frame Uedge = U-value edge of glass Aedge = Area edge of glass Aw = Area Window Uedge Aedge Thanks to Christian Kohler at LBNL for formula verification. * NFRC requires specific IGU values for each window certification. The U-window value is therefore specific to each certification and makes U-frame values difficult to extract for PHPP use.
  7. 7. NFRC Therm file protocols: Ucog Boundary Condition: Temp: 69.8 degF (21 degC) Film Coeff: (Rs) 0.39 BTU/hr.ft2 F (2.19 W/m2 K) (Defined using WINDOW) Uedge Boundary Condition: Temp: 69.8 degF (21 degC) Film Coeff: 0.39 BTU/hr.ft2 F (2.1 W/m2 K) Uf Boundary Condition: Interior Wood/Vinyl Frame Temp: 69.8 degF (21 degC) Film Coeff: (Rs) 0.43 BTU/hr.ft2 F (2.44 W/m2 K) Boundary Condition: NFRC 100-2001 Exterior Temp: -0.4 degF (-18degC) Film Coeff: (Rs) 4.58 BTU/hr.ft2 F (26 W/m2 K) Emmissivity: 0.84 U-factor Surface: Edge U-factor Surface: Frame U-factor Surface: SHGC Exterior (frame exterior only)
  8. 8. NFRC simulation sample results: Ucog = 0.13 BTU/hrft2 F Uw = 0.14 BTU/hrft2 F SHGC = 0.38 VT = 0.51
  9. 9. Sample NFRC certificate: Simulation: 1. Ufactor (whole window includes frame + glass) 2. SHGC (specific to each IGU) 3. Visible Transmittance 4. Air Leakage (optional) Verification: NFRC certification requires destructive testing of a sample window and regular factory inspections to achieve full certification. Image from NFRC website: http://nfrc.org/fenestrationfacts.aspx
  10. 10. How PHI calcs window U-value For certification: (Ug x Ag) + (Uf x Af) + (ψspacer x Lg) Aw Uw = Ug Ag Uf Af Lg Ug = U-value glass1 Ag = Area glass Uf = U-value frame Af = Area frame Ψspacer = psi L g = Length spacer Aw = Area Window ψspacer 1. It is important to note that PHI uses a ‘standard’ IGU rated at 0.123 Btu/hr.ft2F, or 0.7 W/m2K, for all their certification simulations. This generates a U-window (frame + glass) output value, but allows for easy comparison of U-frame values between multiple window profiles. Specific U-glass values are calculated elsewhere in the PHPP for project-specific performance calculation. 2. *Reference Glazing Values are now specific to each Climate Certification. (See chart on Slide #x)
  11. 11. *Uf Boundary Condition: Temp: 68 degF (20 degC) Film Coeff: (Rs) 1.35 BTU/hr.ft2 F (7.67 W/m2 K) PHI Therm file protocols: *Ug Boundary Condition: Temp: 68 degF (20 degC) Film Coeff: (Rs) 1.35 BTU/hr.ft2 F or 0.74 hr.ft2 F/BTU (7.67 W/m2 K) *Boundary Condition: Temp: 14 degF (-10degC) Film Coeff: (Rs) 4.35 BTU/hr.ft2 F or 0.23 hr.ft2 F/BTU (24.69 W/m2 K) U-factor Surface: Interior U-factor Surface: Frame U-factor Surface: none (This page verified by Passive House Academy) *Values are now vary for each Climate Certification. (See chart on Slide #15)
  12. 12. *Exterior Boundary Condition: Temp: 23 degF (-5degC) Film Coeff: (Rs) 4.35 BTU/hr.ft2 F (24.7 W/m2 K) *Interior Boundary Condition: Temp: 68 degF (20 degC) Film Coeff: (Rs) 1.42 BTU/hr.ft2 F (4 W/m2 K) PHI also calculates fRsi*: (Cursor placed at inside edge of glass and frame) (This page PHI verified: Benjamin Krick 7.25.13.) *Values are now vary for each Climate Certification. (See chart on Slide #15)
  13. 13. Uw-installed = • Interior Surface temp difference allowed = 4.2K max. • θopK = operative temperature (average temp of interior room surfaces and interior air temperature.) • θaK = (not clear to author at this time – requires PHI verification) And Uw – Installed: * This page PHI verified: Benjamin Krick 7.25.13. (Ug*Ag) + (Uf*Af) + (ψedge*Lg) + (ψinstall*Lf) Aw
  14. 14. What is fRsi and Uw, installed ? Passive House Certification is essentially a DURABILITY and COMFORT standard. By including requirements for Uw, installed and fRsi, PHI certification checks against interior drafts and interior surface condensation. This ensures a high level of occupant comfort and the elimination of mold growth. Got Mold? Info from PHI component Certification Criteria document: http://www.passiv.de/downloads/03_certification_criteria_transparent_components_en.pdf
  15. 15. Climate Specific Certification: *PHI now issues certificates for Arctic, Cold, Cool-Temperate, Warm-Temperate and Warm climate zones. Note: Criteria for Warm-Temperate and Warm are provisional and therefore subject to change. Images from PHI component Certification Criteria document: http://www.passiv.de/downloads/03_certific ation_criteria_transparent_components_en .pdf (Updated on 7 Feb., 2015)
  16. 16. PHI certification example: Uw = 0.75 W/m2 K Uw,installed = 0.85 W/m2 K Uframe = 0.65 W/m2 K Frame width Ψg(spacer) = 0.024 W/mK fRsi = 0.74 Certified! Image from PHI component database: http://www.passiv.de/komponentendatenbank/files/pdf/zertifikate/zd_northwin_vision_en.pdf
  17. 17. *PHI certification example: The PHI component seal Category Opaque envelope Building services Transparent envelope Efficiency class phC certifiable component phB basic component phA advanced component phA+ very adv. component Climate region Arctic Cold Cool, temperate Warm, temperate Warm Hot Very hot Image courtesy of PHI: www.passivehouse.com
  18. 18. And what’s an Efficiency Class? The Passive House Institute recently added a scaled rating (phA+ to phD) to their certificate. It is based on the ratio of glass to frame and favors thinner frames which may have a higher u-value than their wider-framed counterparts.) ψopaq = ψg + (Uf x Af)/ Lg Images and info from PHI component Certification Criteria document: http://www.passiv.de/downloads/03_certification_criteria_transparent_components_en.pdf
  19. 19. How PHIUS calcs window U-value For certification: (Ug*Ag) + (Uf*Af) + (ψspacer*Lg) Aw Uw = Ug Ag Uf Af Lg Ug = U-value glass * Ag = Area glass Uf = U-value frame Af = Area frame Ψspacer = psi L g = Length spacer Aw = Area Window ψspacer * It appears that PHIUS is using the same simulation protocols as PHI (EN ISO 673, 10077) with outputs structured in a similar format to the NFRC. It also appears PHIUS is calculating specific IGU’s for each frame to generate U-window ratings. This info is based on author study of current PHIUS documentation and has not been confirmed by PHIUS.
  20. 20. Uf Boundary Condition: Temp: 68 degF (20 degC) Film Coeff: (Rs) 1.35 BTU/hr.ft2 F (7.67 W/m2 K) PHIUS Therm file protocols: Ug Boundary Condition: Temp: 68 degF (20 degC) Film Coeff: (Rs) 1.35 BTU/hr.ft2 F or 0.74 hr.ft2 F/BTU (7.67 W/m2 K) Boundary Condition: Temp: 14 degF (-10degC) Film Coeff: (Rs) 4.35 BTU/hr.ft2 F or 0.23 hr.ft2 F/BTU (24.69 W/m2 K) U-factor Surface: Interior U-factor Surface: Frame U-factor Surface: none * Simulation protocols are based on the EU ISO 673, 10077 testing protocols. Author assumption. PHIUS has not confirmed.
  21. 21. PHIUS Climate recommendations: Image from PHIUS info document for window manufacturers – Graham Wright
  22. 22. Sample PHIUS certificate: Simulation: 1. Ufactor (whole window includes frame + glass) 2. SHGC (specific to each IGU) 3. Visible Transmittance 4. Air Leakage (optional) 5. U cog 6. SHGC cog (not including frame) 7. Frame widths 8. U-frame values 9. Psi-spacer value Image from PHIUS info document for window manufacturers – Graham Wright
  23. 23. PHPP inputs required for windows: Ug Ag Uf Af Lg Lf ψinstall ψspacer • U- frame • Frame dimensions (width of jambs, header and sill to edge of glass – Af ) • Ψspacer • Ψinstallation • SHGC (or G-value) • U-glass
  24. 24. What are the differences? So if you just want to build a Passive House… Chart based on most current info publicly available at this time. This chart does not include specific differences between NFRC 100 and ISO 10077, which vary enough to make comparison difficult. Author will revise as new information becomes available. Simulation Req'd Yes Yes Yes Product Test Req'd Yes No No Simulation Protocol NFRC 100 ISO 10077 ISO 10077 Includes specific IGU Yes 3-options Yes Minimum U-window Req'd No Yes No Min. fRsi (Surfac Temp. Factr)No Yes No Min. U-Installed Req'd No Yes No *Author’s Evaluation: Fitness Test | Triathlon |Fun Run
  25. 25. Good luck! (Choose your windows and certifier ahead of time.) Contact: Bronwyn Barry bronwynbarry67 at gmail.com bronwyn at oneskyhomes.com Questions? Thank You!

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