HomeWhat does this value indicate? How much heat escapes through the glass.
The lower the value, the better the glass insulates.
Ug (Glazing Heat Transfer Coefficient)
is a key parameter that indicates how much heat escapes through 1 square meter of insulating glass. The lower the Ug value, the better the glass insulates, resulting in smaller heat losses through the window. It is one of the main factors determining the overall thermal insulation of a window, along with the frame and other parameters.
What influences the Ug value
- Number of panes: Double glazing has a higher Ug (worse), while triple and quadruple glazing have a lower Ug (better).
- Gas filling: Krypton or argon in the inter-pane space improves insulation (lower Ug) compared to air.
- Low-E coatings: Thin coatings on the glass reflect radiant heat back into the interior.
Importance of the Ug value:
Energy efficiency: Low Ug values are essential for low-energy and passive houses.
Unit
Watts per square meter Kelvin W/(m²K)
Related values
Uf: Frame Heat Transfer Coefficient (link to window glossary)
Uw: Overall Window Heat Transfer Coefficient (link to window glossary)
Ψg (Psi): Linear heat transfer coefficient at the frame-glass junction (spacer) (window glossary)
