Bulletproof glass with thermal insulation

Objective

The transparent building envelope poses a critical challenge in safety-sensitive areas of structures. While glazing facilitates interaction between the interior and exterior, it combines this architectural quality with only limited resistance to ballistic impacts. Consequently, thick and heavy single-pane glass sections have typically been used to date, which present significant drawbacks in terms of dead weight, construction, and thermal insulation. At the same time, however, energy requirements for building envelopes are increasing in accordance with the Building Energy Act (GEG).

The ZIM collaborative project between the Chair of Structural Engineering at the University of Siegen and SiLATEC Sicherheits- und Laminatglastechnik GmbH addresses these conflicts by developing innovative bullet-resistant glazing with high thermal insulation. The goal is to design transparent specialty safety glazing that meets the ballistic requirements for bullet resistance according to DIN EN 1063, as well as the energy efficiency and structural constraints of modern facades.

The research includes experimental ballistics tests and numerical simulations to analyze the failure behavior of multilayer composite systems. The focus is on material combinations of glass and plastics. The development of multi-pane insulating glass (MIG) or the targeted integration of vacuum insulating glass (VIG) enables bullet-resistant glazing that significantly improves thermal insulation while reducing the nominal thickness. The results contribute to the further development of energy-efficient facades with both passive and active safety features and open up design possibilities for transparent building envelopes in safety-critical applications. 

Applications of bullet-resistant glass with thermal insulation

• Administrative buildings with heightened security requirements while maintaining transparency
• Embassies and critical infrastructure with requirements for ballistic protection and energy efficiency
• Special-purpose buildings with security requirements
• Facade applications with ballistic resistance and enhanced thermal insulation
• Existing buildings requiring retrofitting with lightweight, slim, bullet-resistant, and energy-optimized glazing
• Public areas requiring enhanced personal protection 

Methodology, Data Basis, and Scope of the Study

• Experimental ballistics tests in accordance with DIN EN 1063
• Numerical simulations based on the finite element method (FEM) for preliminary sizing
• Evaluation of splinter emission, projectile behavior before and after impact, nominal thickness, and self-weight
• Investigation of monolithic and multilayer cross-sections as laminates consisting of float glass (FG), tempered safety glass (ESG), polycarbonate (PC), or polymethyl methacrylate (PMMA), as well as polymer interlayers made of polyvinyl butyral (PVB) and polyurethane (PUR)
• Testing as single-pane glass, multi-pane insulating glass (MIG), and vacuum insulating glass (VIG)
• Study of production at SiLATEC Sicherheits- und Laminatglastechnik GmbH using existing and optimized manufacturing processes 

Results

• Demonstration of the combination of ballistic resistance and thermal insulation in glazing
• Materials such as glass exhibit a significant reduction in projectile velocity, but also pronounced shattering
• Materials such as polycarbonate exhibit lower energy absorption but very good shatter resistance
• Reduction in nominal thickness and weight through the combination of glass and plastic
• Improved thermal performance compared to conventional specialized safety glazing with thermal insulation through integration into multi-pane insulating glass (MIG) or vacuum insulating glass (VIG)
• Contribution to the energy-efficient retrofitting and sustainable upgrading of buildings, taking into account active and passive safety
• Increased transparency and architectural design flexibility