Retrofits in heritage buildings without altering façades. Learn about structure, thermal performance, and case studies.
Preserving heritage façades is both a cultural mission and a regulatory requirement. Across Europe, North America, and Asia, historic buildings face strict conservation rules that forbid altering original windows or decorative frames. Yet these buildings often leak energy, causing high heating and cooling costs.
HaanGlas Vacuum Insulating Glass (VIG) provides a breakthrough: slim-profile glazing that delivers triple-glass insulation values in a thickness of just 6–8 mm, allowing direct replacement of existing glass panes while keeping the original frames intact.
The Structure Behind Slim-Profile VIG
HaanGlas VIG features a 0.15 mm vacuum cavity sealed with precision micro-support pillars and advanced low-temperature edge sealing. The result is a lightweight unit that achieves U-values as low as 0.47 W/m²·K, far outperforming traditional double glazing.
Unlike bulky triple glazing, which requires new, reinforced frames, slim VIG integrates directly into heritage wooden or steel frames. This makes it an ideal solution for projects where visual authenticity is as important as energy efficiency.
Why Historic Retrofits Are So Challenging
Façade restrictions: Original mullions, muntins, and decorative lines must remain untouched.
Frame strength: Old wood or metal frames cannot support heavy triple glazing.
Energy codes: Modern sustainability standards (LEED, Passive House, BREEAM) demand better insulation.
Occupant disruption: Retrofits must minimize downtime and intervention.
Slim VIG resolves all of these pain points by upgrading only the glass unit. This low-intrusion retrofit strategy is both regulator- and architect-friendly.
Energy Savings and Sustainability
According to HaanGlas performance data, replacing old double glazing with VIG can save up to 60% in annual energy consumption.
With U-values below 0.5 W/m²·K and sound insulation levels over 36 dB, VIG also improves comfort while cutting carbon emissions.For historic buildings, this means compliance with today’s demanding energy codes without sacrificing heritage authenticity.
Proven Applications in Heritage Projects
HaanGlas showcases several retrofit applications in its Retrofitting with Energy-Efficient Vacuum Glazing section, where outdated windows were upgraded using slim-profile VIG without any frame replacements.
For larger façade applications, products like Oversized Tempered VIG demonstrate that even monumental heritage structures can benefit from advanced thermal upgrades.
Six Reasons Slim VIG is the Heritage Retrofit Solution
Low-intrusion installation – replace glass, not frames.
Authenticity preserved – façades remain visually identical.
Lightweight design – protects fragile heritage frames.
Superior insulation – U-values down to 0.47 W/m²·K.
Acoustic comfort – >36 dB sound reduction for urban areas.
Proven durability – edge seals tested for decades of performance.
Conclusion
Heritage buildings no longer have to choose between preserving history and achieving energy efficiency. With HaanGlas slim-profile VIG, architects, engineers, and building owners can retrofit aging façades to meet modern sustainability standards—without compromising authenticity.
