FENSA-registered glazing experts. Made-to-measure sealed units, shipped UK-wide, backed by a 10-year warranty.
Clear double glazing — the maximum-light, no-coating default
When daylight matters more than U-value, clear double glazing is the right answer. Pane Relief supplies standard clear sealed units in 4mm-20mm-4mm and 4mm-16mm-4mm builds (24mm and 28mm overall), with no low-E coating, no tinting, and no solar-control film. That gives you around 80% visible light transmittance — the highest in our range — and a neutral, near-invisible appearance through the pane. The trade-off: a slightly higher U-value (around 2.8 W/m²K versus 1.2-1.4 for coated low-E). For internal partitions, listed-building DG-permitted lights, north-facing rooms where heat loss matters less than daylight, and pre-1900 conservation projects where a coating reflection would read wrong on a sash, clear DG is the spec to ask for.
When low-E is the wrong answer
Listed-building consent allowing double glazing in like-for-like sashes will often specify "uncoated clear" to keep external reflection consistent with the originals. Internal partitions, kitchen pass-throughs, and stair-window lights also benefit from maximum daylight rather than the slight green tint of a soft-coat low-E. Free spec advice on the helpline if you're not sure whether coated or uncoated fits the project.
Configure clear DGArchitect, conservation officer, glazier
BS EN 1279-compliant clear DG with full UKCA marking and Declaration of Performance on request. We supply Pilkington Optifloat or Saint-Gobain Planiclear base glass — both are CE/UKCA-marked low-iron-free annealed float, suitable for sash refurb, secondary glazing primary lights, and Grade II DG-permitted retrofits. Trade tier pricing on 5+/20+/50+ orders.
Trade pricing & bulk ordersCommon clear-DG scenarios — pick the closest match
Six typical use-cases where uncoated clear DG is the right call over low-E or solar-control alternatives.
Standard 24mm clear DG
4mm-16mm-4mm argon-filled clear annealed. The default rectangular spec — fits most casement and sash rebates.
28mm clear DG
4mm-20mm-4mm argon-filled clear. Wider cavity for marginally better thermal — newer UPVC and timber profiles.
Slim 14mm clear (heritage)
Krypton-filled slim profile for listed sashes — see the slim DG range for the conservation-grade option.
Internal partitions
Office, studio, or domestic glass walls. Clear DG here for acoustic plus light — no coating needed indoors.
North-facing rooms
Low solar gain rooms (north elevation, shaded) where maximising visible daylight beats coating-driven U-value.
Custom clear DG
Non-standard sizes, shaped, or toughened safety variants — configure live.
Measure twice, order once
Same measure rule as our other sealed units — get the rebate-to-rebate sealed-unit size, not the daylight opening.
The 5-step measure
- Open the window or pop a glazing bead. Measure visible glass width at top, middle, and bottom — use the smallest number.
- Measure visible glass height at left, middle, and right — use the smallest number.
- Add 6mm to both dimensions (3mm of glass tucked into each side of the rebate).
- Measure overall sealed-unit thickness with vernier callipers — clear DG comes in 24mm or 28mm overall by default.
- Send us a photo of the frame profile and rebate depth if you want a sanity-check before ordering. Free service on the helpline.
Pricing transparency
Prices on this collection start at the smallest stock size in base clear spec (4mm-16mm-4mm argon-filled annealed, no coating). Custom sizes, toughened, laminated, shaped, or oversized lights are all priced live in the configurator. Trade accounts unlock tier pricing and Net 30 terms.
Clear double glazing — common questions answered
Q: What's the light transmittance of clear DG, and why does it matter?
Clear annealed double glazing transmits approximately 80-82% of visible daylight through both panes. Add a soft-coat low-E and that drops to around 76-78% (still high, but the coating introduces a faint green or blue tint visible at grazing angles). Solar-control coatings drop transmittance further, to 60-70%. In rooms where natural light is the priority — north-facing offices, internal stair lights, daylight-critical art studios, listed-property primary rooms — the uncoated clear spec is the right choice even if it costs you 0.2-0.4 W/m²K on the U-value.
Q: When should I upgrade from clear DG to low-E?
For most modern habitable rooms — bedrooms, living rooms, kitchens — low-E is the right call. The U-value drop (2.8 → ~1.2 W/m²K) typically saves £80-£140 per window per year in heating costs, paying back the small coating premium within 1-2 winters. Stick with clear DG when (a) you're targeting maximum daylight in a light-priority room, (b) listed-building consent specifies uncoated for like-for-like reflection match, (c) it's an internal partition where heat loss isn't a factor, or (d) you're glazing a porch or unheated space where thermal performance is irrelevant.
Q: Is clear DG ever permitted in a listed building?
Yes — increasingly so. Since the 2017 Historic England guidance shift, many Grade II conservation officers will permit slim or standard DG in like-for-like sashes provided the timber muntins, glazing-bar proportions, and reflection signature match the originals. Uncoated clear is often specified for the reflection-match reason (low-E coatings can read as a faint green tint at grazing angles, which conservation officers may reject). Always confirm the spec with your local conservation officer in writing before ordering. We supply a free spec-sheet for officer sign-off on request.
Q: Does clear DG come with argon fill, or is that an upgrade?
Argon fill is included as standard on all our clear DG units — no upcharge. Argon is denser than air and reduces conductive heat transfer across the cavity by roughly 15%, dropping a clear-DG U-value from around 3.0 W/m²K (air-filled) to around 2.7-2.8 W/m²K (argon-filled). Krypton fill is a further upgrade (useful in narrow-cavity slim units where there's less gap to insulate), available on request — see the slim DG range for krypton-as-standard.
Q: Safety glass — does clear DG come toughened?
Standard clear DG is annealed (non-safety) by default. Toughened (BS EN 12150) or laminated (BS EN 14449) safety upgrades are selectable in the configurator and are legally required in critical locations: any pane below 800mm cill height in a habitable room, within 300mm of a door edge, or anywhere a person could fall against the glass. Bathroom windows, low-cill bedrooms, stair lights, and floor-to-ceiling primary glazing all typically need safety glass. The configurator flags critical-location panels automatically once you enter dimensions and cill height.
Q: Will clear DG meet current Building Regs (Part L)?
On its own, no — current Approved Document L (2022 revision) requires a window U-value of 1.4 W/m²K or better for replacement glazing in dwellings. Standard clear DG sits at around 2.8 W/m²K, which means it does not meet Part L for a notifiable replacement. Use cases where clear DG is still appropriate: like-for-like in a listed building (exempt from Part L for the original fabric), internal partitions (not subject to Part L), unheated outbuildings, and secondary-glazing inner lights (the outer primary light is what's regulated). For Part L-compliant clear-aesthetic glass, ask about Pilkington OptiView — a coated unit with near-invisible coating signature.
Q: How does clear DG compare to triple glazing for daylight?
Triple glazing adds a third pane and therefore another reflective interface — daylight transmittance drops to around 70-72% on a clear TG unit, and lower again on coated TG. If maximum visible light is the priority, double-glazed clear is the right answer. If thermal performance dominates (Passive House standard, large picture windows in a colder microclimate), triple is right — see the 28mm TG or 32mm TG ranges.
Q: What's the warranty and lead time?
Every clear DG unit ships with our 10-year manufacturer warranty on edge-seal integrity (BS EN 1279-2 weathered durability) and full UKCA marking. Stock rectangular sizes ship in 5-7 working days. Non-stock custom rectangular: 7-10 working days. Shaped, arched, or oversized panels (any dimension over 1500mm): 10-14 working days. Toughened or laminated safety variants add 2-3 working days. Free UK mainland delivery on all orders.
Related guides and specifications
Not sure if clear or coated DG is right for the project?
Call the helpline on 0117 330 3057 (08:00-18:00 Mon-Fri), or request a quote. Free spec-match review for listed-building and conservation projects.