Glazing related questions
Glazing related questions

Why is laminated glass a prerequisite?

We believe laminated glass is a prerequisite for rooflights, when being installed above people's heads to secure you and your family.

The laminated glass is constructed by two glass sheets with a very thin layer of polyvinyl butyrate (PVB) between them. This enables the internal layers of laminated glass to have the capacity to absorb the energy of impact and resist penetration.

All our glazing units come with a laminated inner pane.

What is the difference between toughened and laminated glass?

Our rooflights are produced with toughened glass on the outside and laminated glass on the inside. Toughened glass is stronger than the laminated glass of the same size and thickness. Worth mentioning is that toughened glass breaks up into hundreds of tiny pieces, while laminated glass holds in place if shattered. Therefore, we have decided to produce all our rooflights with a laminated inner pane to ensure optimum safety for you and your family.

What is Warm Edge Spacer technology?

All glazing units have a warm edge spacer to ensure a thermal breakage. Warm edge technology minimizes the risk of condensation at the pane edges and provides the glazing units with the most durable insulation capabilities.

What is Uw-value and how does it differ from Ug-value?

The Uw-value indicates the insulating value of the rooflight construction. It is calculated as the heat loss through the entire rooflight construction.
The Ug-value on the other hand, is the heat loss of the insulated glazing unit, measured at the center point of the insulated glazing unit.

These two metrics are completely different. You will often find the Ug-value (insulating properties of the glazing) to be really low, which is good for an insulating value. Whereas the Uw-value (entire rooflight construction) will tend to be somewhat higher.

At Vario by VELUX, we believe it is most accurate to indicate the Uw-value i.e. the insulating properties of the entire rooflight construction, as the Ug-value (insulating properties of the glazing) only provides part of the installed product's true insulating value.

Vario rooflights come with Uw-values between 1.1 to 2.5 [W/(m2K)] and Ug-values between 0.5 - 1.3 [Ug* (W/m2K)]

To see all the specific insulating values of our rooflight constructions and our insulated glazing units, please see our technical table.