TY - CONF T1 - Experimental and Numerical Examination of the Thermal Transmittance of High Performance Window Frames T2 - Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010 Y1 - 2010/09// A1 - Arlid Gustavsen A1 - Goce Talev A1 - Dariush K. Arasteh A1 - Howdy Goudey A1 - Christian Kohler A1 - Sivert Uvsløkk A1 - Bjørn Petter Jelle KW - experimental KW - Fenestration KW - frame cavity KW - heat transfer modeling KW - hot box KW - international standards KW - thermal transmittance KW - U-value KW - window frames AB - While window frames typically represent 20-30% of the overall window area, their impact on the total window heat transfer rates may be much larger. This effect is even greater in low-conductance (highly insulating) windows which incorporate very low conductance glazings. Developing low-conductance window frames requires accurate simulation tools for product research and development.The Passivhaus Institute in Germany states that windows (glazing and frames, combined) should have U-values not exceeding 0.80 W/(m2 K). This has created a niche market for highly insulating frames, with frame U-values typically around 0.7-1.0 W/(m2 K). The U-values reported are often based on numerical simulations according to international simulation standards. It is prudent to check the accuracy of these calculation standards, especially for high performance products before more manufacturers begin to use them to improve other product offerings.In this paper the thermal transmittance of five highly insulating window frames (three wooden frames, one aluminum frame and one PVC frame), found from numerical simulations and experiments, are compared. Hot box calorimeter results are compared with numerical simulations according to ISO 10077-2 and ISO 15099. In addition CFD simulations have been carried out, in order to use the most accurate tool available to investigate the convection and radiation effects inside the frame cavities.Our results show that available tools commonly used to evaluate window performance, based on ISO standards, give good overall agreement, but specific areas need improvement. JF - Thermal Performance of the Exterior Envelopes of Whole Buildings XI International Conference, December 5-9, 2010 CY - Clearwater Beach, FL U1 -

Windows and Daylighting Group

U2 - LBNL-3886E ER -