Pilkington Optitherm™ S1 Plus | Ultra Low-Emissivity Thermal Insulation Glass | Pilkington UK

Pilkington Optitherm™ S1 Plus

Pilkington Optitherm™ S1 Plus

Pilkington Optitherm™ S1 Plus is a UK-manufactured, off-line coated , ultra-low-emissivity (low-e) glass designed to deliver best-in-class thermal insulation with a neutral aesthetic in insulating glass units (IGUs). Engineered to meet the demands of modern UK buildings, it supports compliance with energy regulations and helps reduce heating costs—without compromising on clarity or flexibility.

Key Benefits for UK Fabricators & Glaziers

  • Ug-value 1.0 W/m²K in Double Glazed IGU – In accordance with EN 673
  • Ug-value as low as 0.5 W/m²K in Triple Glazed IGU – Supporting ultra-efficient building envelopes
  • Neutral appearance – High light transmittance and minimal colour shift ensure clear, natural views with no unwanted tint
  • Flexible processing – Supplied as a single coated stock suitable for annealed, toughened or laminated formats, simplifying inventory and reducing lead times
  • Multi-functional integration – Can be combined with Pilkington Optilam™, Pilkington Optiphon™, or other specialist coatings (e.g. solar control, self-cleaning, bird-safe) to meet complex performance needs

Manufactured in the UK

Pilkington Optitherm™ S1 Plus is proudly manufactured in the UK, supporting British industry and ensuring consistent quality, availability and service. Produced to exacting standards at Pilkington’s UK facilities, it benefits from:

  • Local production and supply – helping reduce lead times and simplify logistics for fabricators and IGU manufacturers across the UK
  • Reliable quality assurance – manufactured under ISO-certified processes
  • Support for UK construction and sustainability goals – contributing to lower embodied carbon through reduced transport distances and alignment with national energy-efficiency targets
  • Technical and customer support from UK-based teams – ensuring Investor in Customers (IIC) gold-rated service and expert technical guidance throughout specification, processing and installation

By choosing Pilkington UK, specifiers and fabricators are investing in products that are not only high-performing but also locally made—reinforcing the value of UK craftsmanship in modern glazing solutions.

Supporting UK Regulations & Energy Efficiency Goals

Pilkington Optitherm™ S1 Plus is designed to help specifiers, contractors and installers meet today’s stringent energy standards and future-proof their projects.

  • Supports compliance with Part L of the Building Regulations in England and Wales, and Section 6 in Scotland
  • Helps reduce heating energy demand—enhancing occupant comfort, helping lower heating bills, and reducing carbon emissions
  • Enables windows and façades to achieve low U-values and meet Passivhaus performance targets , contribute to EPC upgrades and qualify for Retrofit Fund initiatives

Energy and Environmental Benefits

Pilkington Optitherm™ S1 Plus contributes to energy-efficient building design by:

  • Reducing excessive heat loss through glazing, helping to lower heating bills
  • Supporting carbon reduction goals in line with the UK’s net-zero strategy
  • Providing thermal comfort in both residential and commercial environments, especially in UK climates

Applications in the UK Market

Pilkington Optitherm™ S1 Plus is suitable for a wide range of high-performance glazing applications:

  • Windows, curtain walls and glazed façades
  • Retrofit and refurbishment projects targeting energy upgrades
  • Commercial buildings with large, glazed areas (e.g. offices, schools, healthcare)
  • Architectural designs prioritising daylight and visual clarity
  • Projects requiring multi-functional glazing (e.g. acoustic, safety, solar control)

Fabrication & Processing

Pilkington Optitherm™ S1 Plus is available in multiple formats to suit trade and project requirements:

  • Annealed for standard IGU configurations
  • Toughened for safety and strength applications
  • Laminated for enhanced acoustic, security or safety performance

Processing Notes:

  • IGUs incorporating Pilkington Optitherm™ S1 Plus should be glazed in accordance with National Standards or Codes of Practice
  • Coated glass should be converted to IGUs within specified timeframes. See Overview of processing times in our Handling & Processing Guidelines
  • Minimal colour shift between batches; for critical visual applications, coordinate glazing runs with manufacturer
  • Confirm compatibility with edge seals with your supplier

The coating for Pilkington Optitherm™ S1 Plus should always face the cavity of an insulating glass unit and is designed to be used on glass surface #3 of a double-glazed unit (counting from the outside).

 

Ready to specify Pilkington Optitherm™ S1 Plus?

Contact your local Pilkington UK representative today for technical guidance, samples, or details of your nearest UK supplier.

 

October 2025
Version UK:2.1.1

 

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