Effective energy balance of common window systems in New Zealand

Abstract

This research describes a mathematical approach based on some well-established methods to assess the Effective Energy Balance of common window systems in New Zealand. Direct comparisons are made between daylighting gain and solar heat gain/loss of a glazing and the solar heat gain/loss of a wall having the same area and with varying thermal resistance values, taking into consideration the effect of orientation, to help clarify the roles of daylight and solar heat radiation in the potential annual energy saving of common window systems. Two of the important findings are (1) daylighting plays an important role in potential energy saving and (2) depending on the percentages of window area on a wall, double glazing will not necessarily result in bigger energy saving than single glazing. While the scope of this study is limited to a 30m x 10m room with different orientations and with different RT values, the results demonstrate that the prediction of Potential Annual Energy Saving is a more useful technique for optimising the energy performance of window systems than the Effective Energy Balance approach.