Is your window frame still stable and windproof enough, then you might consider to immediately replace your current single-glazing by super insulating glazing. The costs for this high yield glass pay themselves back by the money you safe on heating costs. If your window frame is no longer in good condition and cannot be repaired, we advise you to replace your old windows by completely new windows with super insulating glazing. Make sure that both the window frame and the glass insulate properly. Difference in energy loss for single-glazing, double-glazing and super insulating glass. High yield glass insulates five times better than single-glazing and two to three times better than regular double-glazing. The increased thermal comfort is indicated with a U-value (heat transmission rate).
The U-value indicates the heat loss per second, per m² and per degree of temperature difference between indoors and outdoors. The lower this U-value is, the lower the heat loss and the higher the temperature on the inside of the glass. For an outside temperature of 0°C and an indoor temperature of 20°C, the inside of single-glazing has a temperature of 5,6°C and of 17,3°C for high yield glass with U=1.1 W/(m².k). Expressed in energy, you save approximately 44 liters of oil fuel or 36³ of natural gas each year when replacing one square meter of single glass with high yield glass (U = 1.1W/(m².k)). Expressed in money, you safe approximately 36 Euros on oil fuel and 23.55 Euros on natural gas (prices June 2012) per m² of glass. Comparing thermal comfort in Single-glazing, Double-glazing and High-efficiency glazing. The window frame construction is also important. The heat loss via a window frame is also determined by the insulation capacity of the window frames. For metal windows, a thermal break of the window frame is needed. In order to be eligible for the tax reduction, the heat transmission rate of the glass + window needs to have a U-value that is smaller than or equal to 2,0 W/(m².k). Demand of your installer the guarantee that the placed combination of glass + window meets the requirements of the tax measure.