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Good for heat loss
With sliding windows in a highly insulated design, the building envelope remains energy efficient even with a glass content of up to 98 percent.
Good for heat loss
The proportion of transparent surfaces in buildings has been increasing for years. Glass can now insulate just as well as solid facade elements, but at the same time allows a lot of daylight in and gives a modern, more open look. “High-quality glazing makes it possible to avoid heat loss and provide energy-efficient heating - but only in combination with intelligent construction concepts, suitable frame material and professional window installation,” says Dennis Schneider, Managing Director at Sunflex.
Highly insulated windows to prevent heat loss
As many people know, plain glass is not particularly suitable as a thermal insulation material. But a lot has happened in glazing in the last few decades. The heat transfer coefficient (Uw value, which indicates heat loss) has continued to reduce as glazing has developed. Single-glazed windows usually only achieve Uw values of around 4.7 to 6.2 W/mK, conventional insulating glass without coating around 3.0 W/m²K. With triple insulating glass, values of up to 0.4 W/m²K can now be achieved, which means heat losses that are ten times lower than with single glass. Energy-saving windows should have a UW value of less than 0.9 W/(m²K). "For example, we offer our new sliding windows in the highly insulated SF80 version with a Uw value from 0.8 W/m2K - depending on the size and glazing. Even with a glass content of up to 98 percent, the building shell remains energy efficient. And the highly thermally insulated aluminum-glass folding door SF75 also allows for a Uw value of 0.9 W/m2K good insulation values. “In this way, builders benefit from savings while at the same time having a slim profile design,” says Schneider.
Positive heat balance with solar radiation
With low heat losses and high heat gains at the same time, the energy balance of the window surfaces improves even further. The heat gains from a window are greater the more solar radiation it lets through. "If windows are aligned with the sun during building planning and protected against heat loss at night, they can have a better energy balance than a well-insulated external wall. Windows with triple glazing even achieve a positive energy balance. They gain more solar energy during the heating season than is lost in room heat," reports Schneider and adds: "To avoid overheating in summer, shading is important to use. There are also windows with coatings that let in less solar energy.”
Dense frames for energy efficiency
But it's not just the glazing itself that plays an important role in the thermal insulation of windows. Frame structures and assembly connections must also not form thermal bridges. "Warm air escapes from leaky frames - the frame can account for 15 to 35 percent of the heat loss of the entire window. The frame construction therefore also determines energy savings. However, professional installation allows windows to remain both airtight and waterproof over the long term. This not only leads to lower energy consumption, but also to better sound insulation and effective protection against mold," concludes Schneider. (gw)
