EPC ratings increasingly matter — for property value, for prospective buyers, for landlords (the minimum is rising), and for anyone considering an air-source heat pump or solar export tariff. The single biggest contributor to most UK EPCs is the windows.
How EPC scores windows
EPC assessors look at the type, age and rating of your windows. Roughly:
- Single-glazed timber/metal: very poor — the worst category
- Pre-2000 double-glazed: below average
- 2000s–2010s standard double-glazed: average
- A-rated modern double-glazed: good
- A+ / A++ low-E argon-filled double-glazed: very good
- Triple-glazed: excellent
Real-world impact
From the EPCs we've seen post-installation across Staffordshire, replacing pre-2010 double-glazing with modern A+ rated windows typically improves the EPC rating by 4–10 points — generally enough to nudge you up one band, sometimes two if you were on the borderline.
Replacing genuinely old single-glazing or pre-1990 double-glazing produces a more dramatic improvement: 8–18 points, often two bands.
Combining upgrades for best results
If you're EPC-driven (e.g. a landlord trying to hit C, or a homeowner planning solar export), the best returns come from combining upgrades:
- A++ rated windows
- A-rated front and back doors
- Loft insulation top-up to 270mm
- Cavity wall insulation (if not already present)
- Modern condensing boiler or heat pump
What we recommend
For EPC-focused upgrades, specify A++ windows with argon-filled triple glazing on north-facing elevations and Bay/Bow windows. The thermal benefit is materially better than standard double-glazing and the EPC difference is measurable. We routinely specify Deceuninck 2800, VEKA OMNIA and Residence R9 with triple-glazing for EPC-driven projects.
Request a free EPC-focused quote — we'll provide indicative U-values and expected EPC impact based on your current rating.