Replace single or old double glazing with high-efficiency glass
High-efficiency glass insulates two to three times better than ordinary double glazing; replacing 1 m² of single glazing saves about 23 m³ of gas a year.
Do it yourself
Sources checked on .
High-efficiency glass has a thin metal coating and a gas filling such as argon. It insulates two to three times better than ordinary double glazing and four to five times better than single glazing. Its U-value is about 1.1 W/m²K, against 2.9 for old double glazing and 5.8 for single glazing; the lower the number, the better.
To see what you have, look for a U-value or product name on the spacer bar between the panes, or hold a flame near the glass: a reflection with a different colour points to a coating. That test is not always reliable.
New windows make a home more airtight. Plan air supply in the dry rooms at the same time, with grilles in the new windows or a ventilation system, to avoid condensation and mould.
Details
| Impact | Large · Replacing 1 m² of single glazing saves about 23 m³ of gas a year, at least about 200 kWh. Replacing 5 m² or more of single glazing passes 1,000 kWh a year. How we rate impact |
|---|---|
| CO₂ saved | About 40 kg of CO₂ a year per m² of glass, roughly the yearly uptake of 4 forest trees. How we count CO₂ |
| Estimated saving | About 23 m³ of natural gas or 25 litres of heating oil a year for each m² of single glazing replaced, according to the Flemish government. (confidence: medium) |
| Who acts | You (owner) |
| Needs landlord's agreement | No |
| Type | Action |
| Constant or subject to change | Constant · Good practice that barely changes with new laws, prices or services. |
Do this together with
Sources
- Hoogrendementsglas (in Dutch) · Vlaamse overheid (vlaanderen.be) (official source) · checked on
- Verluchting en ventilatie (in Dutch) · Vlaamse overheid (vlaanderen.be) (official source) · checked on