Energy Performance Of Glazing Research Articles

Energy performance of glazings in European climates

Windows can cause significant thermal energy gains or losses in buildings. Focusing on wintertime, a simple method for analyzing and discussing energy flows through glazings is presented. The impact of the glazing quality, the façade orientation, and the severity of the climate on the ratio of solar gains to thermal losses through glazings are shown. As regards the passive solar heating of buildings, the glazing quality is represented by the ratio of the total solar energy transmittance to the thermal transmittance ( g/U). The severity of the climate is determined by the ratio of the interior-exterior temperature difference to the solar irradiance (Δ θ/I). In this study, the method is based on monthly mean values of interior-exterior temperature difference and solar irradiance. Not at least because the approach is straightforward, it might also be valuable for educational purposes. For eight case study locations in Europe namely Bucharest, London, Madrid, Moscow, Rome, Stockholm, Warsaw and Zurich, charts are presented, which display condensed information on the energy performance of glazings. At a given location, the gain-to-loss ratio varies by a factor of roughly 30 depending on the glazing quality and the façade orientation. At all locations and façade orientations, modern triple glazings perform best and enable net gains at south façades in December even in Moscow and Stockholm.

Energy performance of glazings and windows

The purpose of the work is to make it possible to compare the energy performance of different glazings or windows in an easy way. The energy performance is expressed by the net energy gain, which is given as the solar gain minus the heat loss. The net energy gain from glazings and windows both depend on the thermal transmittance (the U-value) and the total solar energy transmittance (the g-value). This fact makes it difficult to choose the glazings or windows with respect to energy performance in a given case. To compare different glazings or windows in an easy way, diagrams have been produced which give the net energy gain based on the orientation, the tilt, the U-value and the g-value of the glazings or windows. In addition, a single diagram showing the net energy gain in a one-family house has been produced which takes into account the orientation of the windows in the building. This makes it possible to evaluate the energy performance of different glazings or windows for a one-family house using a single diagram. The diagrams give an easy way of comparing different glazings or windows so the best solution in a given case can be chosen. In addition, the diagram showing the net energy gain in a one-family house is used in the Danish Energy Labelling and Rating system for classification of glazings.