When shopping for new windows, one term you will come across is U-value. What does it mean?
U-Value = Heat Loss
The U-value (thermal transmittance) measures how well a window keeps heat from escaping. It indicates the amount of heat that passes through the window over time. The lower the U-value, the stronger the window insulation performance.
Why It Matters
- Lower energy bills – Better insulation means less heat loss, so your heating system does not have to work as hard.
- Comfort – Rooms stay warmer in the winter and cooler in the summer.
- Sustainability – Efficient windows help reduce your carbon footprint.
What is a Good U-Value?
- Single glazing: Around 5.0 W/m²K (poor insulation)
- Double glazing: Around 1.2–2.0 W/m²K
- Triple glazing: Around 0.8–1.2 W/m²K (excellent insulation)
Look for windows with a U-value less than 1.6 W/m²K for good performance. In colder climates, aim for even lower.
In Short…
U-value indicates the amount of heat that passes through the window over time. The lower the number, the better. It is a key factor in choosing energy-efficient, comfortable, and cost-saving windows.