{"product_id":"28mm-low-e-a-rated-double-glazed-unit","title":"28mm Low-E A-Rated Double Glazed Unit","description":"\n\u003cp class=\"pr-flagship__lede\"\u003e\u003cstrong\u003eThe A-rated upgrade\u003c\/strong\u003e. A 28mm low-E argon-filled sealed unit (4mm clear \/ 20mm cavity with planitherm soft-coat \/ 4mm clear) delivers a centre-pane U-value of 1.1 W\/m²K and a Window Energy Rating of A under BFRC certification — the spec UK building inspectors expect for Approved Document L compliance on replacement glazing.\u003c\/p\u003e\n\n\u003cp\u003e\"Low-E\" means low-emissivity: a microscopically-thin metallic-oxide coating on the inside face of the inner pane that reflects long-wave heat radiation back into the room while letting visible light through. The Pilkington K-Glass (hard-coat) and Optitherm S1 \/ Planitherm Total+ (soft-coat) families are the UK-standard options — soft-coat performs better thermally but must be sealed inside the cavity (it oxidises if exposed to air, which is why it always faces the cavity, never the room).\u003c\/p\u003e\n\n\u003ch2\u003eTechnical specification\u003c\/h2\u003e\n\u003ctable class=\"pr-spec-table\"\u003e\n  \u003ctr\u003e\n\u003cth\u003eOverall thickness\u003c\/th\u003e\n\u003ctd\u003e28mm\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eBuild-up\u003c\/th\u003e\n\u003ctd\u003e4mm clear \/ 20mm argon cavity \/ 4mm clear with Planitherm Total+ soft-coat (face 3)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eGas fill\u003c\/th\u003e\n\u003ctd\u003e90% argon (BS EN 1279-3)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eSpacer bar\u003c\/th\u003e\n\u003ctd\u003eWarm-edge composite, black (low thermal bridging)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eU-value (centre-pane)\u003c\/th\u003e\n\u003ctd\u003e1.1 W\/m²K\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eU-value (whole window with PVCu frame)\u003c\/th\u003e\n\u003ctd\u003e1.4 W\/m²K\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eg-value\u003c\/th\u003e\n\u003ctd\u003e0.62\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eLight transmittance\u003c\/th\u003e\n\u003ctd\u003e~78%\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eBFRC Window Energy Rating\u003c\/th\u003e\n\u003ctd\u003eA (when fitted in a compliant frame)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eStandards\u003c\/th\u003e\n\u003ctd\u003eBS EN 1279, BS EN 673 (U-value), BS EN 410 (light\/solar)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eWhere this unit is required\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBuilding Regs Approved Document L\u003c\/strong\u003e — Part L1B requires replacement window units to meet a U-value of 1.4 W\/m²K or better. A 28mm Low-E argon unit clears that with 0.3 W\/m²K of headroom.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNew build and significant extensions\u003c\/strong\u003e — Local building control will check that replacement glazing in extensions ≥ 30% of floor area meets Part L. This unit is the default A-rated spec.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCold-room retrofits\u003c\/strong\u003e — North-facing bedrooms, single-glazed conservatories being upgraded, rooms above unheated garages. The 1.1 U-value cuts radiant heat loss roughly 22% vs a standard 24mm argon unit.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eEPC band improvement\u003c\/strong\u003e — Upgrading to A-rated glazing typically lifts an EPC by 5-10 points depending on the existing baseline. For landlords, this is a route to MEES C compliance ahead of the 2028 deadline.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eEnergy-rated glass selection in depth is covered on the \u003ca href=\"\/pages\/energy-rated-glass-units\"\u003e\u003cstrong\u003eenergy-rated glass topical page\u003c\/strong\u003e\u003c\/a\u003e — U-value vs g-value tradeoffs, BFRC vs CE-label differences, and how the WER calculation actually works.\u003c\/p\u003e\n\n\u003ch2\u003eStock sizes and pricing\u003c\/h2\u003e\n\u003cp\u003eFive UK-standard stock sizes are below. Each is dispatched 5-7 working days from a FENSA-registered manufacturing partner. Custom sizes via the \u003ca href=\"\/pages\/configure\"\u003e\u003cstrong\u003econfigurator\u003c\/strong\u003e\u003c\/a\u003e at the same per-m² rate. Trade accounts see tiered pricing on login.\u003c\/p\u003e\n\n\u003ch2\u003eCertification and standards\u003c\/h2\u003e\n\u003cp\u003eEvery unit ships with a UKCA mark, a unique IGU edge-stamp identifying the manufacturer batch, and a Declaration of Performance referencing BS EN 1279 (parts 1, 2, 3, 5, 6). The Planitherm coating carries Saint-Gobain's batch certification. BFRC ratings are issued on the whole-window assembly (frame + glass); the glass alone contributes the U=1.1 centre-pane figure, with the frame contributing the rest.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003ch3\u003eWhat's the difference between A-rated, B-rated, and C-rated glass?\u003c\/h3\u003e\n\u003cp\u003eThe BFRC Window Energy Rating combines U-value (heat loss), g-value (solar gain), and L-factor (air leakage). A-rated requires WER ≥ 0 — meaning solar gain offsets heat loss over a year. C-rated allows WER -20. A 28mm Low-E argon unit in a standard PVCu frame is the simplest path to an A rating.\u003c\/p\u003e\n\n\u003ch3\u003eSoft-coat vs hard-coat low-E?\u003c\/h3\u003e\n\u003cp\u003eHard-coat (Pilkington K) is pyrolytic — fused into the glass at the float-line, durable, can be toughened, slightly worse U-value (~1.5 W\/m²K in a 28mm unit). Soft-coat (Planitherm\/Optitherm) is sputter-deposited, higher performance (1.1 W\/m²K), must live inside the sealed cavity. This flagship uses Planitherm Total+ on face 3.\u003c\/p\u003e\n\n\u003ch3\u003eWill fitting A-rated glass alone improve my EPC?\u003c\/h3\u003e\n\u003cp\u003eYes — replacement glazing scores under \"windows\" in the EPC RdSAP model. The improvement depends on the previous baseline: replacing single-glazed sash windows with A-rated DG can add 8-12 EPC points; replacing first-generation DG (1990s) typically adds 3-5 points.\u003c\/p\u003e\n\n\u003ch3\u003eCan I use this in a listed building?\u003c\/h3\u003e\n\u003cp\u003eListed-building consent is local-authority-dependent. Conservation officers usually accept slim or low-iron variants where sightline matters. The 28mm Low-E is too thick for most original Georgian sash rebates — for those, consider the \u003ca href=\"\/pages\/slim-double-glazing\"\u003eslim Krypton variant\u003c\/a\u003e.\u003c\/p\u003e\n\n\u003ch3\u003eDoes the Planitherm coating tint the glass?\u003c\/h3\u003e\n\u003cp\u003eSlightly. There's a faint neutral\/bronze haze visible at sharp viewing angles, particularly with the sun behind you. From inside looking out, the tint is invisible. Light transmittance drops from ~80% (uncoated) to ~78% — imperceptible in normal use.\u003c\/p\u003e\n\n\u003ch3\u003eWarranty?\u003c\/h3\u003e\n\u003cp\u003e10-year manufacturer warranty on edge-seal integrity (BS EN 1279-2 weathering) and 5-year warranty on coating integrity (Planitherm batch certification). Argon retention warranted to 80% of initial fill at 10 years.\u003c\/p\u003e\n","brand":"Pane Relief","offers":[{"title":"600 × 400 mm","offer_id":61851582660938,"sku":"DG28-LOWE-600x400","price":45.0,"currency_code":"GBP","in_stock":true},{"title":"800 × 600 mm","offer_id":61851582693706,"sku":"DG28-LOWE-800x600","price":59.0,"currency_code":"GBP","in_stock":true},{"title":"1000 × 800 mm","offer_id":61851582726474,"sku":"DG28-LOWE-1000x800","price":98.0,"currency_code":"GBP","in_stock":true},{"title":"1200 × 1000 mm","offer_id":61851582759242,"sku":"DG28-LOWE-1200x1000","price":147.0,"currency_code":"GBP","in_stock":true},{"title":"1500 × 1200 mm","offer_id":61851582792010,"sku":"DG28-LOWE-1500x1200","price":220.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/3515\/2458\/files\/double-glazed-sealed-unit-igu-product-cutaway_fc56842d-dbfd-4b3b-8927-69d95e679010.webp?v=1778952473","url":"https:\/\/panerelief.co.uk\/products\/28mm-low-e-a-rated-double-glazed-unit","provider":"Pane Relief","version":"1.0","type":"link"}