Pilkington Optitherm™ S1 Plus

Pilkington Optitherm™ S1 Plus is a UK-manufactured, off-line coated, low-emissivity (low-e) glass that delivers the best thermal insulation within the Pilkington UK low-e range.

Intended to meet the demands of modern UK buildings, it supports compliance with energy regulations (The Building Regulations 2010 (England) Approved Document L Volume 1) and helps homeowners reduce heating costs—without compromising on clarity.

Ready to specify Pilkington Optitherm™ S1 Plus?

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

The Declaration of Performance (DoP) for our products can be accessed via www.pilkington.com/ce. Supporting test evidence for the DoP can be requested via enquiries@pilkington.com.

April 2026
Version UK:2.1.1

Key Features Applications Downloads
EPD Verified

Key Features

  • Low-e coating reflects heat back into the room, reducing heat loss.
  • Neutral view through glass due to high light transmission.
  • 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.
  • Available in annealed form and can be toughened or laminated without compromising performance or appearance.
  • No edge deletion required when used with Pilkington UK-approved sealants.

 

Applications


Pilkington Optitherm™ S1 Plus is suitable for a wide range of residential and commercial projects:

  • Windows and doors
  • New-build housing/buildings.
  • Replacement and retrofit windows.
  • Areas susceptible to excessive heat loss.
  • Glazed extensions, conservatories and garden rooms.
  • Energy-efficient upgrades to existing homes.

Pilkington Optitherm™ S1 Plus Downloads

Pilkington Spectrum

Pilkington Spectrum is a Windows-based glass performance model which enables you to quickly and efficiently calculate key properties of a wide range of single glazing and insulating glass units. Also available as an app for mobile devices, you can use Pilkington Spectrum to provide the following information:

  • Light and solar properties (transmittance, reflectance, absorptance, g value, etc.).
  • Centre pane Ug-value.
  • Sound insulation values.
  • Global Warming Potential (GWP), or carbon footprint.
  • Ultra violet (uv) transmittance and colour rendering index (Ra).
  • Other properties (e.g. pendulum body impact resistance, fire resistance, resistance to manual attack, etc.).
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