HILIT AEROGEL WINDOW

1. HILIT AEROGEL WINDOW HILIT Highly Insulating and Light transmitting aerogel glazing for window (JOR3-CT97-0187) EnerBuild participant number: 44 Thematic group 5 – Buildings components (incl. windows, facades) Co-ordinator: Karsten I. Jensen Dept. of Buildings and Energy (IBE) Technical University of Denmark (DTU)

2. HILIT AEROGEL WINDOW BACKGROUND Two JOULE II projects French aerogel projects (=> patent) Danish project (assembly apparatus) Swedish pilot plant for aerogel production (high temperature process)

3. HILIT AEROGEL WINDOW • PROJECT OBJECTIVES • Main objectives: • pre-industrial elaboration process evaluation for the chemical part (aerogel process) and the glazing assembly process of aerogel window • to estimate the energetic interest of such glazings. • Other objectives: • Flat aerogel sheets of about 60 x 60 x 2 cm3 with a solar transmittance of 90 % or more and the lowest heat conductivity ever reported for such material.

4. HILIT AEROGEL WINDOW • Other objectives: • Flat aerogel sheets of about 60 x 60 x 2 cm3 with a solar transmit-tance of 90 % or more and the lowest heat conductivity ever re-ported for such material. • The aerogel material exhibits only negligible image blur i.e. the optical quality is at the same level as ordi-nary glass panes. • Feasibility study which analyses the technical potential of aerogel windows.

5. HILIT AEROGEL WINDOW • Other objectives: • Prototypes of 60 x 60 cm5 evacu-ated aerogel glazing (aerogel thickness of 20 mm) made by the proposed process and having a centre heat loss coefficient (U-val-ue) below 0.4 W/m5 K, an overall U-value below 0.5 W/m5 K and a solar energy transmittance (g-val-ue) above 75 %. Finally, the life-time of the glazing with respect to maintaining the gas pressure be-low 50- 100 hPa will be at least 30 years.

6. HILIT AEROGEL WINDOW • Other objectives: • Technical and economic evaluation of an industrial production of • aerogel glazings for windows. • Analysis of market potential of aerogel windows

7. HILIT AEROGEL WINDOW • At the end of the project: • A supercritically CO2 based process with recovery, that can give flat aerogel tiles of 60 cm square as well as a glazing assembly process, suited for an industrial production, for the same size • A general scheme for demonstration of the new technology will be drafted.

8. HILIT AEROGEL WINDOW • Observations: • At the end of year two of three • (ends on 31 October next year). • Potential energy savings and markets – due in year three. • The same for the technical and economic evaluation of an industrial production of aerogel glazings. • The aerogel process: • The patented process is scaled up from a few cm sq to 55 cm sq. • So-called ultra flat and crack-free aerogel tiles are obtained. • Installation of separation and recycling of CO2 has begun.

9. HILIT AEROGEL WINDOW • Observations (cont.): • The aerogel material: • Due to ultra flatness, the image blur related to the surfaces is decreased. • Improvements still needed on the bulk related image blur. • Heat conductivity – • ~ 16 mW/m K (amb. gas pressure) • ~ 8 mW/m K (gas pressure below 50 hPa)

10. HILIT AEROGEL WINDOW • Observations (cont.): • The glazing: • Five prototypes made by means of the Aerogel Glazing Evacuation and Assembly (AGEA) apparatus.

11. HILIT AEROGEL WINDOW • Observations (cont.): • The latest prototype is made with aerogel produced within the project. • Aerogel thickness: 18 mm • 4 mm low iron glass panes, • 60 cm x 60 cm • Rim seal; plastic foil and butyl • It failed (leaked), but is going to be repaired. • Outdoor measurement: • Solar transmittance (direct-hemispherical): 72%. • Application of “non-reflective coating” can increase the value by 2 –3 points

12. HILIT AEROGEL WINDOW Observations (cont.): Prototype number five:

13. HILIT AEROGEL WINDOW • Observation (cont.): • The present optical quality sufficient for so-called secondary applications, i.e. • sky lights • bath rooms • day lighting • green houses • white goods etc. • Or as transparent insulation; • solar collectors • solar walls etc.

14. HILIT AEROGEL WINDOW • Observation (cont.): • Strengths: • high solar transmittance and • high insulation at the same time • Weaknesses: • the aerogel must be protected from liquid water, • rough vacuum (gas pressure below 50 – 100 hPa) required • Problems: • the optical quality of the aerogel material not at the same level as for ordinary glass panes

15. HILIT AEROGEL WINDOW • Project status • progress in good accordance with the work programme • both the material process and the glazing process are shown to be feasible • the material process – safe and low temperature is possible • the glazing process – evacuation and assembly within a few minutes • the glazing – high solar transmittance and low U-value and almost no cold bridge at the edge • no problems of paramount importance encountered – so far

16. HILIT AEROGEL WINDOW • CONCLUSION • Both the material process and the glazing process have been improved much • It seems possible to develop an aerogel glazing with an overall U-value close to the centre U-value • The optical quality of aerogel still needs to be improved for application as ordinary glazings, but sufficient for secondary applications • OUTLOOK • Demonstration phase planned • Other applications considered