A440.2-M1991

1.1 This Standard applies to fixed and operable windows, covered by CSA Standard CAN/CSA-A440, and to sliding glass doors, covered by CGSB Standard CAN/CGSB-82.1, that are factory-assembled and intended for vertical installation in buildings. Note: The term "window" is often used within this Standard to include both windows and sliding glass doors. 1.2 This Standard specifies both measurement and calculation methods for establishing the following window thermal properties for both residential and commercial applications: (a) overall heat transmission coefficient (U-value); and (b) solar heat gain coefficient (F). The window thermal properties are established for specific indoor and outdoor conditions. These properties will not be constant under actual conditions. Nevertheless, the values obtained by the methods specified are considered to provide an acceptable basis for comparing performance in use. 1.3 This Standard specifies a method for determining an energy performance rating (ER value) for windows under heating conditions in residential applications that come under Part 9 of the National Building Code of Canada. The energy rating equation includes factors for solar heat gain, heat loss by transmission, and heat loss by air leakage. The energy rating calculation assumes vertical installation in a typical residence and is based on average conditions for solar radiation incident on windows facing the four cardinal compass directions and representative climate zones in Canada. The energy rating provides a method for comparing different window products on the basis of their effect on the annual energy supplied by the house heating system. CSA Special Publication A440.3 (the user guide to CSA Standard A440.2) provides data and instructions for determining ER values for specific locations, orientations, and window sizes (ERS). It also provides advice on how to use these ERS values to determine the approximate increase or decrease in seasonal energy use associated with windows. 1.4 The following were not considered in the preparation of this Standard: (a) store fronts; (b) nonoperable portions of curtain walls; (c) fixed glazing cast into precast concrete panels; (d) greenhouse windows; (e) storm doors; (f) skylights; (g) sloped glazing; (h) curved glazing; (i) hinged doors; and (j) glass blocks. 1.5 This Standard does not address the ability of windows to retain thermal properties and air tightness over time under conditions of use.