New ISO 15099 Standard

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New ISO 15099 Standard

• By D. Charlie Curcija, Ph.D.
• Center for Energy Efficiency and Renewable Energy
  
• University of Massachusetts
• Amherst, MA
• U.S.A.
• AcknowledgementsThis work was sponsored by the
  Assistant Secretary for Conservation and
  Renewable Energy, Office of Building and
  Community Systems, Building Systems Division of
  the United States Department of Energy

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BRIEF OVERVIEW

• Development of standard started in 1994
• Based on ASHRAE SPC 142P
• Currently in FDIS stage
• Expected to be sent for final vote very soon
• Expected to be approved
• Already in use in NFRC rating system
• Implemented in THERM and WINDOW programs

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MAIN FEATURES

• Best science
• Three main sections
• Center of glass
• Frame/Edge of glass
• Shading devices
• Minimum ambiguity and room for interpretation
• Complex calculation routines suitable for
  computer program

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CENTER OF GLASS CALCULATIONS

• Alternative methods for overall U-factor
• Linear thermal transmittance (Europe)
• Area weighted method (USA)
• Heat balance for n-layer glass matrix
• Non-linear system of equations solved for
  temperatures and radiosities
• Gas mixture algorithms
• Ray tracing solar optical calculations
• Solar Heat Gain Coefficient (SHGC) for overall
  glazing system
• Visible transmittance (VT)

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N-LAYER MATRIX
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FRAME/EDGE CALCULATIONS

• Two-dimensional (2-D) heat transfer equations
  (energy equation in 2-D)
• Convective and radiative boundary conditions
• Rules for meshing and error estimation
• Frame cavity calculations (effective
  conductivity)
• Convection heat transfer for horizontal and
  vertical orientation
• Radiation calculations
• Rules for rectangularizing frame cavities
• Thermal bridges treatment

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SHADING DEVICES CALCULATIONS

• Screens, curtains and Venetian blinds
• Optical properties calculations
• Diffuse reflection
• Direct transmission
• Thermal properties calculations
• Convection and radiation heat transfer between
  IGU and shading device
• Ventilation
• Shading device openness

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CONCLUSIONS

• ISO 15099 is accurate and reliable standard
• Implemented in computer tools and available for
  use
• Conflicting existing simulation standards should
  be phased out
• Future development should include more accurate
  treatment of complex systems

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THE END For more information http//www.ceere.or
g http//www.nfrc.org http//windows.lbl.gov http
//www.eren.doe.gov