{"product_id":"44mm-premium-triple-glazed-krypton-low-e-unit","title":"44mm Premium Triple Glazed Unit (Krypton + Soft-Coat Low-E)","description":"\n\u003cp class=\"pr-flagship__lede\"\u003e\u003cstrong\u003eThe Passivhaus spec — without the bespoke German lead time\u003c\/strong\u003e. A 44mm premium triple-glazed unit (4mm \/ 16mm krypton + soft-coat low-E \/ 4mm \/ 16mm krypton + soft-coat low-E \/ 4mm) delivers a centre-pane U-value of 0.5 W\/m²K and a whole-window U-value of 0.7-0.8 W\/m²K in a thermally-broken frame — meeting the Passivhaus Institut's strict 0.8 W\/m²K window requirement for cool-temperate climates.\u003c\/p\u003e\n\n\u003cp\u003eThis is the spec the Scandinavian and German new-build market has used as a baseline for two decades. In the UK, it appears in Passivhaus retrofits (EnerPHit), Future Homes Standard pilot projects, and any deep-retrofit where fabric heat-loss is being driven below 15 kWh\/m²·yr. It is the most thermally-efficient mainstream IGU available, and the spec heat-pump-led retrofits depend on to keep flow temperatures at 35-45°C.\u003c\/p\u003e\n\n\u003ch2\u003eWhy both krypton fills AND dual low-E coatings\u003c\/h2\u003e\n\u003cp\u003eEach thermal layer compounds. Krypton at 16mm in this unit's wider cavity gives ~10% additional benefit over argon (the cavity is just shallow enough that krypton still outperforms). Soft-coat low-E on faces 3 and 5 — the inner surfaces of each cavity — reflects long-wave radiant heat back into the warm side of each cavity. The dual-coating strategy means each cavity does roughly half the work, instead of single-coating loading all the thermal performance onto one face.\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\u003e44mm\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eBuild-up\u003c\/th\u003e\n\u003ctd\u003e4mm clear \/ 16mm krypton \/ 4mm clear (Planitherm face 3) \/ 16mm krypton \/ 4mm clear (Planitherm face 5)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eCavities\u003c\/th\u003e\n\u003ctd\u003e2 × 16mm krypton-filled (BS EN 1279-3 verified ≥90%)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eSpacer bars\u003c\/th\u003e\n\u003ctd\u003e2 × warm-edge composite, black low-conductivity\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eU-value (centre-pane)\u003c\/th\u003e\n\u003ctd\u003e0.5 W\/m²K\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eU-value (whole window in thermally-broken alu\/timber frame)\u003c\/th\u003e\n\u003ctd\u003e0.7-0.8 W\/m²K\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eg-value\u003c\/th\u003e\n\u003ctd\u003e0.50 (slightly lower than standard triple — dual coating trade)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eLight transmittance\u003c\/th\u003e\n\u003ctd\u003e~70%\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 Passivhaus frame)\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eWeight\u003c\/th\u003e\n\u003ctd\u003e~30 kg\/m² — confirm hinge \/ sash rating\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003ctr\u003e\n\u003cth\u003eStandards\u003c\/th\u003e\n\u003ctd\u003eBS EN 1279, BS EN 673, BS EN 410, PHI window certification compatible\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eWhere this unit is the right call\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePassivhaus and EnerPHit projects\u003c\/strong\u003e — Passivhaus Institut whole-window requirement is ≤ 0.8 W\/m²K for cool-temperate climates. This unit delivers it in a standard frame.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHeat-pump retrofits\u003c\/strong\u003e — ASHPs operate most efficiently at low flow temperatures (35-45°C). Premium triple cuts fabric heat loss enough that an ASHP can hold setpoint without bumping flow temperature into the high-COP penalty zone.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFuture Homes Standard pilot builds\u003c\/strong\u003e — the 2025+ FHS draft envelope targets whole-window U ≤ 0.8 W\/m²K. This spec is the cleanest path.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eEPC band A targets\u003c\/strong\u003e — for landlords planning ahead of the proposed 2030 MEES B (or future C-ratchet), premium triple is the glazing spec that consistently scores band-A.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNorth-facing principal rooms in deep-retrofit projects\u003c\/strong\u003e where every kWh of fabric heat loss matters and the install budget can absorb the premium.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eThe whole-window thermal math, BFRC vs PHI certification, and a side-by-side payback analysis against A-rated double is on the \u003ca href=\"\/pages\/triple-glazing\"\u003e\u003cstrong\u003etriple glazing topical page\u003c\/strong\u003e\u003c\/a\u003e. For Building Regs Approved Document L compliance only (not Passivhaus), the lower-cost \u003ca href=\"\/products\/36mm-standard-triple-glazed-unit\"\u003e36mm Standard Triple Glazed Unit\u003c\/a\u003e is the practical choice.\u003c\/p\u003e\n\n\u003ch2\u003eStock sizes and pricing\u003c\/h2\u003e\n\u003cp\u003eFive UK-standard stock sizes below. Dispatch 10-14 working days (premium krypton + dual coating extends lead time vs standard triple). Custom sizes via the \u003ca href=\"\/pages\/configure\"\u003e\u003cstrong\u003econfigurator\u003c\/strong\u003e\u003c\/a\u003e — including Passivhaus-certified frames, oversized panes (\u0026gt;1500mm), and asymmetric panes for combined thermal-plus-acoustic stacks.\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eFrame load note:\u003c\/strong\u003e at ~30 kg\/m² this unit is materially heavier than double glazing. Hinge capacity, frame reinforcement, and sash-balance specifications need to be checked. For a 1500 × 1200 unit, that's roughly 54 kg — outside the capacity of many budget PVCu profiles. Confirm with your frame supplier before specifying.\u003c\/p\u003e\n\n\u003ch2\u003eCertification and standards\u003c\/h2\u003e\n\u003cp\u003eUKCA-marked, BS EN 1279 compliant. PHI-certified component manufacturers carry a Passivhaus stamp — request this batch stamp at order for Passivhaus project documentation. The dual Planitherm coatings carry Saint-Gobain's batch certification. Krypton retention is warranted to ≥80% of initial fill at 10 years.\u003c\/p\u003e\n\n\u003ch2\u003eFrequently asked questions\u003c\/h2\u003e\n\u003ch3\u003eIs the premium over standard triple worth it?\u003c\/h3\u003e\n\u003cp\u003eDepends on the energy strategy. For a heat-pump-led deep retrofit driving toward 15 kWh\/m²·yr fabric demand: yes — the 0.3 W\/m²K centre-pane reduction integrates over a heating season into measurable kWh savings. For Building Regs replacement on a 1980s extension: probably not — the standard triple does the regs job at ~70% of the cost.\u003c\/p\u003e\n\n\u003ch3\u003eWill my frame take this unit?\u003c\/h3\u003e\n\u003cp\u003eModern 70-90mm thermally-broken aluminium and timber-aluminium composite frames are designed for 44-48mm units. Older 60mm PVCu and most 1990s aluminium will not accept it — you'd be replacing the whole window assembly, not just reglazing. Send a frame profile photo to \u003ca href=\"\/pages\/contact-us\"\u003eour contact form\u003c\/a\u003e for compatibility advice before ordering.\u003c\/p\u003e\n\n\u003ch3\u003eWhy is g-value lower than standard triple?\u003c\/h3\u003e\n\u003cp\u003eTwo soft-coat low-E layers vs one in a standard triple. Each coating reflects some short-wave solar plus most long-wave radiant. Two coatings reflect more solar — that's the price of the U-value improvement. For south-facing principal rooms in colder climates, the passive solar loss is real and worth modelling against the U-value win.\u003c\/p\u003e\n\n\u003ch3\u003eKrypton retention over 25 years?\u003c\/h3\u003e\n\u003cp\u003eIndustry standard is \u0026lt;1% per year under EN-1279-2 accelerated weathering. Over 25 years that's ~22% total. At ~78% krypton + 22% air, centre-pane U-value rises from 0.5 to ~0.55 W\/m²K — still well inside Passivhaus territory. Edge-seal failure is the real long-term risk (15-25 years), not krypton diffusion.\u003c\/p\u003e\n\n\u003ch3\u003ePassivhaus certification — what's actually required?\u003c\/h3\u003e\n\u003cp\u003ePHI window certification is on the whole-window assembly (frame + glass + spacer + installation method), not on the glass alone. This unit is a PHI-compatible component — fitted into a PHI-certified frame, the assembly can be PHI-certified. Glass-only certification is not a thing.\u003c\/p\u003e\n\n\u003ch3\u003eComparison with vacuum-insulated glazing (VIG)?\u003c\/h3\u003e\n\u003cp\u003eVIG (Pilkington Spacia, LandVac, FineoVacuum) offers similar U-values in a 6-8mm overall thickness — useful for heritage retrofits where slim DG can't deliver enough thermal performance. Cost is 3-5× higher per m². For mainstream new-build and major retrofit where rebate depth isn't constrained, premium triple is the cost-optimal route to Passivhaus thermals.\u003c\/p\u003e\n\n\u003ch3\u003eWarranty?\u003c\/h3\u003e\n\u003cp\u003e10 years on edge-seal integrity. 10 years on krypton retention to ≥80% of initial fill. 5 years on each Planitherm coating (separate Saint-Gobain certifications per face). Whole-window Passivhaus performance is warranted on the frame manufacturer's terms — confirm with your frame supplier.\u003c\/p\u003e\n","brand":"Pane Relief","offers":[{"title":"600 × 400 mm","offer_id":61853203628362,"sku":"TG44-PREMKR-600x400","price":54.0,"currency_code":"GBP","in_stock":true},{"title":"800 × 600 mm","offer_id":61853203661130,"sku":"TG44-PREMKR-800x600","price":108.0,"currency_code":"GBP","in_stock":true},{"title":"1000 × 800 mm","offer_id":61853203693898,"sku":"TG44-PREMKR-1000x800","price":179.0,"currency_code":"GBP","in_stock":true},{"title":"1200 × 1000 mm","offer_id":61853203726666,"sku":"TG44-PREMKR-1200x1000","price":268.0,"currency_code":"GBP","in_stock":true},{"title":"1500 × 1200 mm","offer_id":61853203759434,"sku":"TG44-PREMKR-1500x1200","price":402.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0895\/3515\/2458\/files\/triple-glazed-insulated-glass-unit-igu-cutaway_b9d55c0d-89a0-4b10-be78-51ce1e018902.webp?v=1779007264","url":"https:\/\/panerelief.co.uk\/products\/44mm-premium-triple-glazed-krypton-low-e-unit","provider":"Pane Relief","version":"1.0","type":"link"}