Double Glazed Aluminium Casement Windows | 5+20A+5 Low-E Argon | SGL
Shaanxi SGL Doors&Windows Technology Co., Ltd. is one of the most reliable manufacturers and suppliers of double glazed aluminium casement windows | 5+20a+5 low-e argon | sgl in China, also supports customized service. Please feel free to wholesale high quality double glazed aluminium casement windows | 5+20a+5 low-e argon | sgl for sale here from our factory. If you have any enquiry about pricelist and quotation, please feel free to email us.
Product Description
Why Double Glazing is the Right Choice for Most Projects
Double glazing strikes the optimal balance between performance and cost. A 5+20A+5 insulated glass unit with Low-E coating and argon filling delivers approximately 60% better thermal performance than single glazing, while costing 40-50% less than triple glazing. For temperate climates - covering most of the UK, Western Europe, the US East Coast, and coastal Australia - this is the specification that meets building regulations without overspending.
The 20mm cavity width is deliberate. Narrower cavities (12-16mm) allow more thermal bridging across the gap. Wider cavities (24mm+) provide diminishing returns and increase frame depth unnecessarily. Twenty millimetres is the engineering optimum validated by decades of building physics research. Our units use argon gas - 67% less thermally conductive than air - and a Low-E coating on the inner pane's cavity-facing surface to reflect radiant heat back into the room.
IGU Quality That Outlasts the Building
The weak point of any double glazed window is the edge seal. SGL uses dual-seal technology: a polyisobutylene (PIB) primary seal for gas retention, backed by a polysulphide or silicone secondary seal for structural integrity. The aluminium or warm-edge spacer contains molecular sieve desiccant to absorb residual moisture. Every unit is tested to EN 1279 Parts 2 and 3 for gas leakage and moisture penetration before leaving the factory.
Independent accelerated ageing tests show our IGUs retain over 80% of the original argon fill after the equivalent of 20 years in service. In practical terms, this means the thermal performance you specify on day one is the performance you get for the lifetime of the building. And if something does go wrong, our 5-year glass warranty covers replacement.
Double Glazing Features
5+20A+5 Low-E Argon as Standard
Not an upgrade - this is our baseline specification. The 5mm clear outer pane withstands windborne debris and thermal shock. The 5mm Low-E inner pane reflects long-wave infrared radiation back into the room. The 20mm argon-filled cavity suppresses convective heat transfer. Together they achieve 1.6 W/m²K - compliant with UK Part L and EU EPBD for new dwellings.
35-42 dB Noise Reduction
The mass-air-mass principle of double glazing naturally attenuates sound: the two glass panes vibrate at different frequencies, and the gas cavity dampens sound wave transmission. A 5+20A+5 unit achieves 38-40 dB reduction - enough to cut 70 dB street traffic to a quiet 30 dB indoors. For airports or motorways, specify a 6.38mm laminated inner pane to reach 42-45 dB.
85% UV Protection for Interiors
Our standard Low-E coating blocks approximately 85% of ultraviolet radiation while transmitting 75%+ of visible light. This protects timber floors, upholstery, artwork, and retail merchandise from photodegradation and fading without making interiors feel gloomy. For museums or galleries, we offer laminated glass with a dedicated UV-interlayer that blocks 99% of UV.
Dual-Seal IGU with 20-Year Argon Retention
PIB primary seal + polysulphide secondary seal + desiccant-filled spacer = an IGU that retains over 80% argon after 20 years of equivalent ageing. This is verified by independent EN 1279-2 gas leakage testing. The desiccant prevents internal condensation (fogging) by maintaining cavity dew point below −40°C.
6+16A+6 Upgrade for Large Units
For oversized casement windows (above 1,500mm in either dimension), we recommend 6mm panes with a 16mm cavity. The thicker glass increases structural strength and improves sound insulation by 2-3 dB. The slightly narrower cavity maintains thermal performance because the increased glass mass offsets the reduced gap. Custom configurations available on request.
Warm-Edge Spacer Option
Standard aluminium box spacers create a thermal bridge at the IGU perimeter. Our optional warm-edge spacers (Swisspacer or TGI) use stainless steel composite or thermoplastic materials that reduce edge U-value by approximately 0.2 W/m²K. This may seem small, but on a full facade it can be the difference between passing and failing a Part L SAP calculation.
Suitable For
Double glazed aluminium casement windows are the standard specification for projects where cost, performance, and compliance must balance:
- Residential Housing Developments
- Apartments & Condominiums
- Student Accommodation
- Hotels & Serviced Apartments
- Retail & High Street Frontages
- Office Buildings (Temperate Climates)
- Renovation & Replacement Projects
our aluminum window Application
our factory
Client Visit
Frequently Asked Questions
Q: Q1: What is a 5+20A+5 double glazed unit?
A: 5+20A+5 describes an insulated glass unit (IGU) with two 5mm glass panes separated by a 20mm air/argon gap (the 'A' stands for air or argon). The outer pane is typically clear tempered glass, while the inner pane carries a Low-E coating that reflects radiant heat back into the room. This configuration balances thermal performance, sound insulation, and cost - making it the most popular specification for residential and commercial aluminium casement windows.
Q: Q2: How much sound do double glazed casement windows block?
A: SGL double glazed aluminium casement windows achieve 35-42 dB sound reduction, depending on glass thickness and cavity width. A 5+20A+5 unit with argon filling typically blocks 38-40 dB - sufficient to reduce busy street noise to a quiet indoor level. For extreme noise environments (airports, motorways), we offer laminated inner panes that increase performance to 42-45 dB.
Q: Q3: Is double glazing enough for cold climates?
A: Double glazing with Low-E coating and argon filling achieves a U-value of 1.6 W/m²K, which meets building regulations in most temperate climates (UK, France, Northern US, coastal Australia). For sub-zero winter regions (Canada, Scandinavia, Central Asia) or Passivhaus projects, triple glazing is recommended for U-values below 1.4 W/m²K. We offer both options and can advise based on your local climate and energy code.
Q: Q4: How long does the argon gas last in double glazed units?
A: Our IGUs use dual-seal technology (PIB primary seal + polysulphide or silicone secondary seal) with desiccant-filled spacers. Independent testing shows argon retention above 80% after 20 years - well beyond the typical building lifecycle. The units are certified to EN 1279 parts 2 and 3 for gas leakage and moisture penetration. In the unlikely event of seal failure, the 5-year glass warranty covers replacement.
Q: Q5: Do double glazed windows block UV rays?
A: Yes. Our standard Low-E coated inner pane blocks approximately 85% of UV radiation while maintaining 75%+ visible light transmittance. This protects interior furnishings, flooring, and artwork from fading without making rooms feel dark. For maximum UV protection (museums, galleries, high-end retail), we can specify laminated glass with a UV-interlayer that blocks 99% of UV while still allowing 70%+ visible light through.
Project Case Studies
We provide one-stop door and window solutions for individual buyers, contractors, renovation companies, and more.
Our address
No. 2 Group, Fumiao Village, Laojun Town, Hantai District, Hanzhong City, Shaanxi Province, China
Phone Number
+86 13335450021
sgl-factory@sgl-doors-windows.com
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Double Glazed Unit Specifications
| Specification | Details |
|---|---|
| Glass Configuration | 5+20A+5 (standard) / 6+16A+6 (upgraded) |
| Outer Pane | 5mm clear tempered glass |
| Inner Pane | 5mm tempered Low-E glass (surface #3 coating) |
| Cavity Fill | Argon gas (90%+ fill rate) |
| Cavity Width | 20mm (16mm / 24mm optional) |
| Spacer | Aluminium box / Warm-edge (Swisspacer optional) |
| U-Value | 1.6 W/m²K (double Low-E argon) |
| Sound Insulation | 35 – 42 dB (laminated inner pane: 42-45 dB) |
| Light Transmittance | ≥ 75% |
| Solar Heat Gain (SHGC) | 0.45 – 0.55 |
| UV Rejection | ≥ 85% |
| Sealing | Dual-seal: PIB primary + polysulphide secondary |
| IGU Certification | EN 1279-2 (gas) / EN 1279-3 (moisture) |
| Frame Material | Aluminium Alloy 6063-T5 |
| Opening Type | Inward / Outward |
| Profile Thickness | 1.4mm / 1.6mm / 2.0mm |
| Surface Finish | Powder Coating / Anodizing / Wood Grain |
| Certifications | CE (EN 14351-1), ISO 9001:2015 |
| Warranty | 10-year frame / 5-year glass & hardware |
- 5+20A+5 IGU as standard - 5mm clear outer + 20mm argon cavity + 5mm Low-E inner
- U-value 1.6 W/m²K - meets UK Part L, EU EPBD, AU NCC for temperate climates
- 35-42 dB sound reduction - busy street noise reduced to quiet indoor levels
- 85% UV blocking - protects furnishings from fading without darkening rooms
- Dual-seal IGU technology - EN 1279 certified, 20-year argon retention
- Factory-direct - 19 years experience, 9,000 m² plant, CE & ISO 9001
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