Window Energy Rating in Ireland — What the Label Means and Why It Matters for BER
On this page
Window Energy Rating (WER): A+ to E scale. The whole-window U-value is what counts for BER, not the glass alone.
Window Energy Rating (WER) in Ireland: A+ to E scale. The whole-window U-value is what counts for BER, not the glass alone. A+ rated windows: U-value 0.7–0.9 W/m²K. A rated: 0.9–1.2. B rated: 1.2–1.4. C and below: 1.4+. BER A1 needs A or A+ rated windows. Part L 2022 minimum is C (U-value 1.4). The supplier should provide a WER label for every window. The label includes: the brand, the model, the U-value, the solar heat gain coefficient, and the air leakage. Check the label before you order — it's the easiest way to compare windows across brands.
When this matters most
You're comparing windows and need to understand the labels.
When this doesn't apply
You've already specified the windows.
Sources
NSAI, Window Energy Rating scheme. https://www.nsai.ie/
Frequently asked questions
What is a Window Energy Rating (WER)?
An A+ to E scale rating of the whole window (glass + frame + spacer). The label includes: brand, model, U-value, solar heat gain coefficient, and air leakage. Required for every window in Ireland.
What WER do I need for BER A1?
A or A+. U-value 0.7–1.2 W/m²K whole-window. Part L 2022 minimum is C (1.4).
Where can I find the WER label?
On the window itself, in the supplier's brochure, or on the NSAI website. Ask the supplier for the label before you order.
When this matters most
You're comparing windows and need to understand the labels.
When this doesn't apply
You've already specified the windows.
Where to go next
Next decision
The next step in your build sequence.
- Door Budget for a Self-Build in Ireland — Internal Doors, External Doors, and Ironmongery →
- Front Door in Ireland — Composite, Timber, Aluminium, and What the BER Counts →
- Garage Door in Ireland — Sectional, Roller, or Up-and-Over, and What the BER Counts →
- Passive House Windows in Ireland — U-value, Frame, and What the Certifier Wants →
- Sliding Doors in Ireland — Aluminium Sliders, Lift-and-Slide, and the U-value Trade-Off →
- Window Installation in Ireland — Cavity Closer, Dpc, and the Airtightness Detail →
Branch into
Adjacent decisions at the same stage.
Watch out for
Common mistakes, hidden costs, gotchas.
Compare with
Alternative approaches worth knowing.