The effect of glass coating emittance and frame rebate on heat transfer through vacuum and electrochromic vacuum glazed windows

Yueping Fang, Philip Eames

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

The thermal performance of an electrochromic vacuum glazing and a vacuum glazing with a range of low-emittance coatings and frame rebate depths were simulated for insolations between 0 and 1000 W m−2 using a three-dimensional finite volume model. The vacuum glazing simulated comprised two 0.4 m×0.4 m glass panes separated by a 0.12 mm wide evacuated space supported by a 0.32 mm diameter pillar array spaced at 25 mm. The two glass sheets were sealed contiguously by a 6 mm wide metal edge seal and had either one or two low-emittance coatings. For the electrochromic vacuum glazing, a third glass pane on which an electrochromic layer was deposited was assumed to be sealed to an evacuated glass unit, to enable control of visible light transmittance and solar gain and thus improve occupant thermal comfort. It is shown that for both vacuum glazing and electrochromic vacuum glazings, when the coating emittance value is very low (close to 0.02), the use of two low-emittance coatings only gives limited improvement in glazing performance. The use of a single currently expensive low-emittance coating in both systems provided acceptable performance. Deeper frame rebate depths gave significant improvements in thermal performance for both glazing systems.
Original languageEnglish
Pages (from-to)2683-2695
Number of pages13
JournalSolar Energy Materials and Solar Cells
Volume90
Issue number16
DOIs
Publication statusPublished - 16 Oct 2006

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Vacuum
Heat transfer
Glass
Coatings
Incident solar radiation
Thermal comfort
Seals
Metals
Hot Temperature

Keywords

  • Vacuum glazing
  • Electrochromic vacuum glazing
  • Finite volume model
  • Low-emittance coating
  • U-value
  • Windows
  • Frames

Cite this

The effect of glass coating emittance and frame rebate on heat transfer through vacuum and electrochromic vacuum glazed windows. / Fang, Yueping; Eames, Philip.

In: Solar Energy Materials and Solar Cells, Vol. 90, No. 16, 16.10.2006, p. 2683-2695.

Research output: Contribution to journalArticle

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abstract = "The thermal performance of an electrochromic vacuum glazing and a vacuum glazing with a range of low-emittance coatings and frame rebate depths were simulated for insolations between 0 and 1000 W m−2 using a three-dimensional finite volume model. The vacuum glazing simulated comprised two 0.4 m×0.4 m glass panes separated by a 0.12 mm wide evacuated space supported by a 0.32 mm diameter pillar array spaced at 25 mm. The two glass sheets were sealed contiguously by a 6 mm wide metal edge seal and had either one or two low-emittance coatings. For the electrochromic vacuum glazing, a third glass pane on which an electrochromic layer was deposited was assumed to be sealed to an evacuated glass unit, to enable control of visible light transmittance and solar gain and thus improve occupant thermal comfort. It is shown that for both vacuum glazing and electrochromic vacuum glazings, when the coating emittance value is very low (close to 0.02), the use of two low-emittance coatings only gives limited improvement in glazing performance. The use of a single currently expensive low-emittance coating in both systems provided acceptable performance. Deeper frame rebate depths gave significant improvements in thermal performance for both glazing systems.",
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