01540nas a2200133 4500008004100000050001400041245003600055210003400091520113400125100002501259700002901284700002201313856007101335 1994 eng d aLBL-3529800aWINDOW 4.1: Program Description0 aWINDOW 41 Program Description3 a

WINDOW 4.1 is a publicly available IBM PC compatible computer program developed by the Windows and Daylighting Group at Lawrence Berkeley Laboratory for calculating total window thermal performance indices (i.e. U-values, solar heat gain coefficients, shading coefficients, and visible transmittances). WINDOW 4.1 provides a versatile heat transfer analysis method consistent with the rating procedure developed by the National Fenestration Rating Council (NFRC). The program can be used to design and develop new products, to rate and compare performance characteristics of all types of window products, to assist educators in teaching heat transfer through windows, and to help public officials in developing building energy codes.

WINDOW 4.1 is an update to WINDOW 4.0. The WINDOW 4 series is a major revision to previous versions of WINDOW. We strongly urge all users to read this manual before using the program. Users who need professional assistance with the WINDOW 4.1 program or other window performance simulation issues are encouraged to contact one or more of the NFRC-accredited Simulation Laboratories.

1 aArasteh, Dariush, K.1 aFinlayson, Elizabeth, U.1 aHuizenga, Charlie uhttps://facades.lbl.gov/publications/window-41-program-description01036nas a2200157 4500008004100000050001400041245005600055210005400111520051900165100002900684700002500713700002200738700002300760700001800783856007700801 1993 eng d aLBL-3394300aWindow 4.0: Documentation of Calculation Procedures0 aWindow 40 Documentation of Calculation Procedures3 a

WINDOW 4.0 is a publicly available IBM PC compatible computer program developed by the Building Technologies Group at the Lawrence Berkeley Laboratory for calculating the thermal and optical properties necessary for heat transfer analyses of fenestration products. This report explains the calculation methods used in WINDOW 4.0 and is meant as a tool for those interested in understanding the procedures contained in WINDOW 4.0. All the calculations are discussed in the International System of units (SI).

1 aFinlayson, Elizabeth, U.1 aArasteh, Dariush, K.1 aHuizenga, Charlie1 aRubin, Michael, D.1 aReilly, Susan uhttps://facades.lbl.gov/publications/window-40-documentation-calculation