Pilkington has launched K Glass™ S, a UK-manufactured low-emissivity (low-e) glass designed to reduce heat loss through window glazing while maintaining high light transmission. The product, coated off-line, reflects infrared heat back into interior spaces and allows passive solar gain, positioning it as a compliance tool for fabricators and installers working to UK Building Regulations 2010 (England) Approved Document L Volume 1, which mandates minimum band B Window Energy Ratings (WER) for new windows in Table 4.2.
The glass achieves its thermal performance through a low-e coating that reflects long-wave infrared radiation while transmitting short-wave solar radiation. This dual function reduces heat loss while permitting solar heat gain. According to the manufacturer, K Glass™ S can help window systems achieve WER band A and higher across PVC-U, timber, and aluminium frame types, exceeding the regulatory minimum.
The product's neutral appearance stems from high visible light transmittance, a feature that distinguishes it from some insulating glass configurations where low-e coatings introduce colour casts. Pilkington states the coating maintains its neutral view-through characteristics in both annealed form and after toughening or lamination. No edge deletion is required when the glass is sealed with Pilkington K Glass™ S-approved sealants, simplifying fabrication protocols. The product is available in annealed form and can be processed into toughened or laminated safety glass without compromising optical or thermal performance.
The UK Building Regulations 2010 Approved Document L Volume 1 sets minimum energy performance thresholds for new and replacement windows. Table 4.2 requires windows in dwellings to achieve at least WER band B, a metric that combines U-value, g-value, and air leakage. Low-e coatings are a standard specification route to meet this threshold. By enabling WER band A performance, K Glass™ S provides a margin above the regulatory minimum.
Pilkington identifies several target applications for K Glass™ S: new-build housing and commercial buildings, replacement and retrofit window installations, conservatories and garden rooms, and insulating glass units for uPVC, aluminium, or timber frame systems. K Glass™ S is manufactured in the UK, reducing lead times and freight costs for domestic fabricators. The product is supported by handling and processing guidelines, test reports, and technical support from Pilkington UK representatives. Declarations of Performance are accessible via the manufacturer's website at www.pilkington.com/ce.
