Replacement, upgrade and specialist double glazing, made to your measurements and delivered across the UK
FENSA Registered BS EN 1279 10-Year Warranty
Trade pricing & bulk orders
Standard double-glazing — like-for-like replacement units
Like-for-like sealed-unit replacement at the spec your existing frame was built for — the "no surprises" route. If your window or door already has double-glazing and it's failed (misted, blown, cracked), you usually don't want a thermal-spec upgrade — you want exactly what was there before, so it drops back into the existing rebate without modification, the U-value matches the surrounding panes, and the visual finish is consistent across the property. This collection is that workhorse: 24mm or 28mm argon-filled low-E units, BS EN 1279 compliant, BFRC-rated, made to your dimensions in 5-7 working days. The flagship product on this page covers the most-ordered build; everything else is one click away in the configurator.
Replacing a failed unit, no upgrade needed
Free delivery to Bristol (BS) postcodes (£180 inc. VAT elsewhere on the UK mainland), 10-year manufacturer warranty on edge-seal integrity (BS EN 1279-2), FENSA-registered installer recommendations in your postcode, and a phone helpline (9am–5pm, Mon–Fri) for measurement sanity-checks. Most standard double-glazed units ship in 5-7 working days. Spec-match service: send a photo of the existing edge-seal and we'll match the build.
Configure my unitInstaller or FM running like-for-like jobs
Trade accounts, tiered volume discount on 5+/20+/50+ unit orders, scheduled site delivery for repair-rota work, priority dispatch. UKCA-marked, BS EN 1279-compliant; Declaration of Performance and BFRC ratings shipped on request. Standardised stock builds in the configurator for fast quote and order.
Trade pricing & bulk ordersOnly one product showing? Here's why.
This collection deliberately surfaces the single most-ordered standard double-glazed build as a flagship product — the spec we ship more of than anything else. For non-standard dimensions, every other variant (alternative cavity build, A+ low-E, krypton, toughened, laminated, acoustic, slim-profile, oversized) is built to spec via the configurator. You're never limited to what's visible on this page.
24mm flagship
4-16-4 argon-filled low-E. U-value 1.4 W/m²K. The UK's most-installed sealed-unit spec since 2010.
Custom dimensions
Enter your width, height, and cavity build for live pricing. Same lead time, same warranty.
Full DG range
All double-glazed cavity builds, coatings, gas fills, and safety options. Use this if you're spec-shopping.
Slim 14mm / 16mm
For Victorian sash, conservation, and listed-building retrofit where original rebate is shallow.
By window type
Casement, sash, bay, tilt-and-turn. Use the window-type finder if you're not sure what build your frame takes.
Measure twice, order once
Standard double-glazed units come in fixed cavity builds. A 28mm unit won't fit a 24mm rebate (or vice versa). Get the thickness right.
The 5-step measure
- Measure the visible glass width at top, middle, and bottom — use the smallest.
- Measure the visible glass height at left, middle, and right — use the smallest.
- Then add 25mm to the width and 25mm to the height for the sealed-unit size.
- Measure the existing unit thickness edge-on with vernier callipers — typically 24mm or 28mm. This is the critical dimension. Don't guess.
- Photograph the kitemark or BS EN reference printed on the edge of the existing unit — we'll use it to spec-match the low-E coating and gas fill.
Pricing transparency
Prices include VAT. The "from" price on each product page is for the smallest stock-size 24mm low-E argon-filled unit at base spec — the flagship. Custom dimensions, A+/A++ coatings, krypton fill, safety glass, acoustic interlayers, and oversized panels are all priced live in the configurator. No quote-only spec lock-in, no hidden surcharges — what the configurator shows is what you pay (plus VAT and any postcode surcharge).
Standard double-glazing — common questions answered
Q: Why is there only one product visible in this collection?
By design — we surface the single most-ordered standard double-glazed sealed unit as the flagship for this category. If your spec exactly matches (24mm argon-filled low-E, rectangular, within stock-size range), it's the fastest path to order. For any other size or build, the configurator covers every variant — alternative cavities (20mm, 28mm), upgraded coatings (A+ low-E, krypton), safety glass, acoustic interlayers, oversized panels, shaped units. The flagship isn't the limit; it's the express lane.
Q: Is "standard" double-glazing different from "double-glazing"?
Yes — "standard" here means the like-for-like rebuild of what's already there: 24mm or 28mm cavity, argon-filled, basic low-E coating, BFRC C/D-rated, built to current Building Regs Part L minimum (U-value 1.4 W/m²K). The broader double-glazing collection covers premium variants — A+/A++ rated, krypton-filled, acoustic, conservation slim-profile. Standard is the right choice if you're replacing one failed unit in an otherwise-fine frame; the broader range is for upgrade scenarios.
Q: Will a like-for-like replacement match the surrounding panes visually?
Almost always. Modern soft-coat low-E coatings (the standard since 2010) are colour-neutral and visually consistent across manufacturers. The visible difference between a fresh unit and a 5- or 10-year-old neighbour is typically imperceptible from inside the room and fractional from the street. The exception is if your existing units have an older hard-coat coating (slightly green tint) — flag it on the order and we'll match the tint.
Q: How long has the current "standard" spec actually been current?
The 24mm argon-filled low-E build has been the UK volume default since around 2010 — driven by the introduction of BFRC ratings (2008) and tightening Building Regs Part L (2010, 2013, 2022 revisions). Before that, the standard was 4-12-4 air-filled with no low-E coating (still common in 1990s housing — and the typical failure-replacement scenario). Pre-1990s, 4-6-4 or 4-8-4 air-filled were standard. We can match any of these older specs if you want strict visual consistency in older property.
Q: Should I take the chance to upgrade while replacing the failed unit?
Honest answer: depends on which unit failed and how many others are similar age. One failed unit out of many: don't bother upgrading (mismatched coatings can look slightly different, and the marginal energy gain on one window is minimal). Multiple failures across the property: yes, upgrade — go A+ low-E or low-E + krypton across the lot, you'll get a meaningful U-value drop and consistent finish. Whole-property retrofit triggered by energy bills: upgrade and consider whether the frames themselves need replacing too.
Q: Does the flagship spec hit current Building Regulations?
Yes — comfortably. Approved Document L (Conservation of fuel and power) requires U-value 1.4 W/m²K or better for replacement glazing in existing dwellings. The 24mm argon-filled low-E flagship hits 1.3-1.4 (varies slightly with low-E supplier and gas fill quality). BFRC C-rated minimum, often B. SAP/EPC calculations and BFRC certification surfaced on request for compliance evidence.
Q: Lead time, warranty, and what happens if I get the size wrong?
Stock-size flagship 24mm units: 5-7 working days. Custom-size rectangular double glazing: 5–7 working days. 10-year manufacturer warranty on edge-seal integrity (BS EN 1279-2 weathered durability), 10-year on coatings. If a unit is mis-measured, we remake it and you pay the same price again — so the free phone sanity-check exists precisely so you don't get to that stage. 0117 330 3057, 9am–5pm Mon–Fri.
Q: Do you supply BS EN 1279 documentation and BFRC rating certificates?
Yes — every unit ships UKCA-marked with BS EN 1279 compliance as standard. Declaration of Performance documents (DoP) and BFRC rating certificates are available on request for any order — flag at checkout or email sales@panerelief.co.uk with the order reference. Useful for Building Control sign-off, FENSA certification, or insurance documentation.
Related guides, collections, and specifications
Spec it in 60 seconds or call us for a sanity-check
Helpline 0117 330 3057 (9am–5pm, Mon–Fri), or request a quote. Trade accounts unlock live tier pricing.