How much can I save on heating costs with new windows?

The underrated principle: the window as a heater

When people think about windows and energy, insulation is usually the first thing that comes to mind. That's correct - but only half the story. Windows do something else too: they let sunlight, and with it warmth, into the room.

"The window is often reduced to its insulating capacity, and therefore to the Uf or Uw value. What gets forgotten is that the energy gained from the sun is actually the bigger factor. The window captures energy and supports the heating system. With the right window configuration, the energy gained exceeds the energy lost."

In concrete terms: a well-configured window can bring in more energy over the course of a year than it loses. Salamander myWindow's calculation for a cubic house with three standard windows:

Energy balance: three modern windows compared (Salamander myWindow)

• 844 kWh/a | Solar heat gain from sunlight

• 425 kWh/a | Heat loss through the window area

• +419 kWh/a | Positive heat balance - the window delivers energy

Chamber technology: what's behind good insulation values

A window's U-value (Uw) indicates how much heat is lost per square metre and degree Kelvin of temperature difference - the lower, the better. Modern uPVC windows with a 5- or 6-chamber profile now achieve values that would have been unthinkable 15 years ago.

"The bluEvolution system provides first-class insulation, keeping the warmth inside the home. Certified by the Passive House Institute, it achieves impressive values thanks to thermal steel and sustainable EvoCore."

The flagship model bluEvolution 82 from Salamander myWindow achieves a Uw value of 0.73 W/(m²K) - that's Passive House standard. By comparison, an old single-glazed window from the 1970s has a U-value of around 5.0 W/(m²K) - seven times the heat loss.

Technical specifications, bluEvolution 82 (Salamander myWindow)

• Uw value: 0.73 W/(m²K) | Passive House suitable

• Uf value MD: 0.98 W/(m²K)

• 6-chamber technology with proven sealing system

• Thermal steel: cold bridges eliminated, structural strength retained

• EvoCore in the frame: fully separable and recyclable

• Eligible for funding: KfW funding up to Passive House standard

What this means in everyday life: lower costs, more comfort

A Uw value of 0.73 instead of, say, 2.5 (typical for old double glazing) means in practice: significantly lower heating bills, no cold draughts near the window in winter, and less condensation. That's not a marketing promise - it's physics.

And then there's the funding on top: anyone installing windows with Passive House-standard values can apply for grants through KfW. Salamander myWindow supports buyers through this entire process - from the configurator through the partner installer to the funding application.

Financial benefits at a glance

• Reduced heating costs thanks to outstanding insulation values (5- and 6-chamber profile)

• KfW funding: eligible up to Passive House standard

• Increased property value through an energy-efficient, high-quality product

• Greater appeal when letting or selling

Tip for older buildings: the right window configuration pays off

Renovating a period property brings a particular challenge: the windows need to suit the architecture - while still offering modern insulation. Salamander myWindow solves this with the C3 principle: Climate (location and light), Case (building type), and Customer (individual preferences) all feed into the choice of window.

The result: a window that not only looks good, but is precisely tailored to the building's energy situation. Whether it's a south-facing aspect with maximum solar gain or a north-facing façade with optimised insulation - the myWindow app helps you make the right decision.

Conclusion: new windows pay for themselves

The question "Is it worth replacing your windows?" has a clear answer: yes - if you choose the right windows. Lower heating costs, KfW funding, increased property value, and a cosier feel thanks to more light and less draught all make a strong case.

Salamander myWindow makes getting started easy with the myWindow configurator: in under five minutes, your details are captured and passed on to specialist retailers.