1. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment DUPPEG Durable Peak Performance Evacuated Glazing Enerbuild No. 51 Centre for Sustainable Technologies University of Ulster Dr Philip Eames

2. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment Introduction  High heat loss through conventional glazing and the increased need to conserve energy has led to the increased use of highly insulating glazing systems.  Current technology for low heat loss windows usually comprises multiple panes of glass with low emittance films and inert gases.  Consequently visibility and solar gain is reduced, units are wide, heavy and difficult to install particularly to existing buildings.

3. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment Current vacuum glazing technology l Glass sheets are rigidly fused together using a solder glass edge seal l Entire system is heated to around 450°C and allowed to cool l Evacuation of the window is achieved through a pump out tube attached to one of the glass panes l High temperature sealing - incurs high embodied energy - precludes the use of tempered glass

4. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment Evacuated glazing l Vacuum glazing consists of two sheets of glass, hermetically sealed, with an evacuated gap between the glass sheets l An array of support pillars is used to keep the glass sheets apart after evacuation l Long wave emittance coatings may be used on the inner glass surfaces to reduce radiative heat transfer

5. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment

7. Potential market uptake Future research & development Links, potential synergies with other RTD projects (worldwide) Links with industry Strengths, weaknesses and competition

8. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment Schematic representation of an evacuated glazing Indium Edge Seal Support Pillar Array (exaggerated size) Glass Panes Soft Low Emittance Coatings

9. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment Low temperature edge sealing using Indium l Indium has the ability to join materials with greatly mismatched co-efficients of thermal expansion subject to thermal cycling l Indium has the ability to ‘wet’ or ‘cold weld’ to metals, glass and ceramics l Indium can mould itself to the shape of the materials being sealed

10. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment Vacuum chamber used for the production of evacuated glazing

11. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment Typical evacuated glazing sample manufactured at the University of Ulster

12. Energy Environment & Sustainable Development Thematic Network on Energy in the Built Environment Conclusions l A hermetic edge sealing technique for evacuated glazing using indium and its alloy’s at temperatures <200°C has been developed l Allows the use of soft low emittance coatings and tempered glass l Reduces embodied energy l Sealing temperatures are below the thermal tolerances for tempered glass - allows thinner glass sheets to be used - allows an increased pillar array spacing thereby - reduces the area of thermal conduction path - reduces the area of thermal conduction path - provides a less visually intrusive pillar array l Manufacturing in vacuum chamber eliminates the need for a pump out tube