Old windows are responsible for the biggest heat loss. Replacing the windows first gets the most out of the façade insulation — we see it on every site.
With every façade renovation, clients ask us the same question: where do we start? Our answer is almost always the same: with the windows. Not because they are the prettiest, but because they are the biggest leak in the envelope.
The biggest heat loss
Old windows let heat, draughts and noise through. New double or triple glazing reduces heat loss by 15 to 25%. Only when the window is right can the insulation around it do its job.
15–25%less heat loss with new glazing
214new windows in Mechelen
294new windows in Wachtebeke
Why the windows first?
- The biggest leak first. Old windows are responsible for the biggest heat loss of the façade.
- The connection is right. Planning windows and insulation together means reveals and sills are finished in one go — without thermal bridges.
- Immediate savings. You notice the difference in heating costs from the first winter.
- Quiet. New windows also keep outside noise out — the residents in Tielt-Winge noticed it straight away.
Airtight installation is as important as the glass
A window is only as good as its installation. We set the frame level and stress-free, finish the connection airtight and insulate under the sills with XPS — so heat loss disappears at the critical connections.
- Frame fixed level and stress-free.
- Airtight connection: no draughts, no thermal bridge.
- XPS insulation under the sills, as in Gent and Neerpelt.
- Window ventilation planned before the window is manufactured.
Window replacement is the first step of a façade renovation. That way you get the maximum out of the façade insulation and save on heating costs straight away.
Grava Group
