Windows & Glass

Windows (timber/aluminium).

Timber windows have the lowest CO₂ footprint. Choose timber or timber/aluminium windows with U-value below 1.0 W/m²K for the best energy and climate profile.

Key Figures

Carbon Footprint (GWP): 35 kg CO₂-eq/m²
Density: varierer
Expected Lifespan: 30–60 år

What is windows (timber/aluminium)?

A window is a combined unit of frame and glass. Carbon footprint varies significantly by frame material: timber windows have low footprint, aluminium windows are high, and composite (timber/alu) is in between. Energy efficiency (U-value) is the most important parameter for climate impact over lifespan.

Carbon Footprint Compared

Timber window ← this material 20 kg CO₂/m²

Timber/aluminium composite 40 kg CO₂/m²

Aluminium window (recycled) 50 kg CO₂/m²

Aluminium window (primary) 100 kg CO₂/m²

Negative carbon footprint (green) indicates carbon storage. Data based on EPD averages from ECO Platform and estimates per EN 15804.

Typical Applications

check_circle Residential windows
check_circle Facade windows and elements
check_circle Roof windows
check_circle Patio doors and sliding windows

In Renovation

Window renovation is typically the energy renovation measure with the shortest payback period, especially going from single to double or triple glazing. Always specify the U-value and be aware of cold bridges in the frame.

Questions about windows (timber/aluminium)

What is the CO₂ difference between timber and aluminium windows?

Timber windows have GWP of approximately 15–25 kg CO₂/m². Aluminium windows (primary alu) 80–120 kg CO₂/m². Timber/alu composite 35–50 kg CO₂/m². Timber is clearly best climatically.

Which windows require least maintenance?

Aluminium windows are almost maintenance-free (no painting needed). Timber/alu composite requires only interior maintenance. Timber alone requires painting/oiling externally every 3–7 years.

When should windows be replaced?

Windows should be replaced when: U-value is above 2.5 (single glazing), there is condensation in thermal panes, the frame is rotted, or draughts cause discomfort. Energy renovation typically includes window replacement.

Is it better to replace only the pane or the whole window?

If the frame is in good condition and original glass thickness/frame size permits, the pane can be replaced alone. This is cheaper and reduces waste. A carpenter or window manufacturer can assess whether this is possible.

Related Materials

Windows & Glass

Glass

GWP: 0.86 kg CO₂/kg

Structure

Structural Timber

GWP: −0.72 kg CO₂/kg

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