Heritage Double Glazing – The Latest Glass Technology
When choosing glass for historic buildings in the UK, you need to balance energy efficiency, aesthetics, and compliance with building regulations and heritage conservation requirements. The best options depend on the specific needs of the building and its listing status. Slim double glazing for heritage projects sounds great on paper — but there is a better alternative.
New Glazing Technology
Advanced new glass technology called vacuum glazing. Fineo vacuum glazing is created by AGC Glass Europe and is a far superior option for heritage projects or conservation areas. It consists of two panes of glass, like double glazing, but instead of a larger gas filled cavity it has a 0.1mm vacuum gap. This innovation means Fineo is similar in thickness to single glazing but has the thermal insulation of triple glazing. The ultra-thin profile of 7.7mm and low U-value of 0.7 W/m2K means Fineo vacuum glazing can be easily retrofitted into historic timber window frames while complying with building regulations.
Compare Slim Double Glazing With Fineo Vacuum Glazing
Slim double glazing and Fineo vacuum insulated glazing (VIG) are both designed to improve thermal efficiency while maintaining a thinner profile than standard double glazing. However, they differ a lot in construction and performance.
Overall Thickness | Glass Thickness | Cavity | Gas | Coating | U-value | Guarantee | |
FINEO Vacuum Glazing | 7.7 mm | 4 mm | 0.1 mm | NONE | Low E | 0.7 | 20 Years |
Low Sightline Slim Double Glazing | 10 mm | 3 mm | 4 mm | Krypton/ Xenon | Low E | 1.9 | 5 Years |
Slim Double Glazing 12mm | 12 mm | 4 mm | 4 mm | Krypton | Low E | 1.9 | 10 Years |
Slim Double Glazing 14mm | 14 mm | 4 mm | 6 mm | Krypton | Low E | 1.5 | 10 Years |
Slim Double Glazing 16mm | 16 mm | 4 mm | 8 mm | Krypton | Low E | 1.3 | 10 Years |
Slim Double Glazing 18mm | 18 mm | 4 mm | 10 mm | Krypton | Low E | 1.1 | 10 Years |
Construction & Design
Slim Double Glazing: Consists of two panes of glass separated by a narrow air or gas-filled space (typically argon, krypton, or xenon). The cavity is smaller than in traditional double glazing, usually around 4–10 mm.
Vacuum Insulated Glazing (VIG): Fineo consists of two panes of glass with an ultra-thin vacuum gap (usually 0.1 mm). The vacuum eliminates heat transfer through conduction and convection.
Thermal Performance (U-Values)
Slim Double Glazing: Offers a U-value of around 1.1–1.9 W/m²K, depending on size of the cavity and gas used.
VIG: Fineo vacuum glazing offers much lower U-value of 0.7 W/m²K, making it comparable to or better than triple glazing.
Thickness & Weight
Slim Double Glazing: Typically 10–18 mm thick, making it suitable for retrofitting into certain frames types but not all.
VIG: Fineo is extremely thin at 7.7 mm, making it the best option for historic or listed buildings as the original frames can be restored and retained with the single replaced with vacuum glazing.
Durability & Lifespan
Slim Double Glazing: The sealant around the edges can degrade over time, allowing gas to escape, reducing efficiency. Lifespan is typically 15 years.
VIG: Fineo has a longer lifespan because there’s no gas to leak out. It can last 60+ years and has a market leading warranty of 20 years.
Suitability
Slim Double Glazing: Can be used in certain projects but may not meet all criteria for building regulations.
VIG: Fineo vacuum glass is best for heritage buildings, listed properties and conservation areas. The glass complies with building regulations and has been approved by Historic England.
