Thermal Performance Optimization of Double and Triple Glazing Systems for Slovenian Climate Conditions

Anita Prapotnik Brdnik

doi:10.3390/su132111857

Abstract

Glazing elements are an important part of the thermal envelope of a building. Therefore, good thermal performance of glazing elements can improve indoor comfort and reduce annual maintenance costs and CO2 (carbon dioxide) emissions by reducing heat loss. Reducing heat loss through glazing elements during the heating season can be achieved by combining low thermal transmittance with high solar heat gain. Using standardized calculation methods and measured climate data for three Slovenian locations representing typical continental, mountainous and Mediterranean climates, this study predicts the best combination of optical properties (emissivity, transmittance and reflectance) of glass panes in double and triple glazing systems that contribute to minimal heat loss. It was found that for the double glazing system, the minimum heating and cooling demand for buildings with low solar gains or high solar gains and applied shading is achieved by an inner pane with high transmittance without low-emissivity coating, and an outer pane with low-emissivity coating with minimum possible emissivity. In Maribor and Portorož climatic zones, the panes with low emissivity coating should be used as inner panes in buildings with high solar gains. For triple glazing, the minimum heating and cooling requirements are achieved with two or three panes with low emissivity. For buildings with low solar gains, an emissivity of the coating of 0.03 is preferable, but for buildings with high solar gains, lower emissivity values should be used.

Highlights

Windows represent an important element of the building envelope, providing daylight, views of the external environment, and natural ventilation [1]
Since building energy consumption is responsible for 20% to 40% of CO2 emissions [8], efforts to reduce heat loss through glazing systems are of great importance
Since the model does not include the effects of the window frame and the thermal bridge between the window and the wall, it is important to mention that if the heat transfer coefficient of the glazing is much higher than the heat transfer coefficient of the wall, the effective thermal transmittance of the glazing will be higher than predicted due to the resulting thermal bridge

Summary

Introduction

Windows represent an important element of the building envelope, providing daylight, views of the external environment, and natural ventilation [1]. As these factors play an important role in indoor comfort [2,3,4], glass elements are becoming increasingly important, leading to the development of buildings with large areas of the building envelope covered with glass elements, such as glass buildings [5] and buildings with double-skin facades [6,7]. The heat transfer coefficient indicates the ability of the glazing to reduce heat loss. In wellinsulated buildings with a large window area, a high total solar transmittance can

Methods

Results

Conclusion