Zircon addition to ceramic roof tiles increases solar reflectance, potentially reducing the urban heat-island effect and lowering demand for internal cooling of buildings

It has been shown that zircon can assist architects in lowering the environmental footprint of buildings they design.

A study has concluded that the addition of zircon increases the solar reflectance of ceramic tiles. A paper summarizing the findings of the study was presented at the ECerS conference in Turin (June 2019). It reported how if zircon-containing ceramic tiles are used as a building envelope, they improve the thermal comfort within the building by reducing energy requirements. When compared to other existing solutions including paints and cool paints, it reduces maintenance costs due to the high resistance of ceramic tiles to wear, dirt and stains.

The study, commissioned by the Zircon Industry Association and Centro Ceramico (Bologna), evaluated the effect of adding zircon to ceramic glazes of various colours.

Carried out both on a laboratory scale and by field trials, zircon was added to 36 tile samples both as an opacifier directly into the glaze formulation (up to 10wt%), and as frit component (up to 6.6 wt%). The solar reflective index (SRI) was calculated on all samples. The colorimetric coordinates were also determined, to evaluate any colour variation due to the presence of zircon. The thermal performance of the samples was automatically monitored every 30 minutes in an outdoor environment during the hot Italian summer period (June to September 2018).

Results of tests carried out on the samples of glazed ceramic tiles show that, in general, the addition of zircon increases the solar reflectance index (SRI) of the glazes, the effect being more pronounced when zircon is added as an opacifier. Also, as the zircon percentage in the glaze increases the SRI value increases linearly for all the colours analysed. Monitoring of the surface temperatures of the tile samples when exposed outdoors to solar radiation confirms that the higher values of brightness and solar reflectance parameters of the glaze are associated entirely to the addition of zircon.

Dr Keven Harlow, Executive Director, Zircon Industry Association commented:

“Environmental impact is increasingly important in today’s world. This study shows that by actively choosing zircon-containing tiles for the building envelope, architects and their customers can significantly reduce the overall environmental impact of the building, while lessening the roof maintenance required over time.

“This study, coupled with the recent Life Cycle Assessment (LCA) of zircon sand, demonstrates the value and benefit of zircon as a material in today’s world where there is a continuing drive to minimize our environmental impact.”

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Notes to editors

  1. Download a copy of the paper presented at the XVI ECerS Conference, Turin, (16-20 June 2019).
  2. The Zircon Industry Association (ZIA) is an independent industry association. Its mission is to represent and support the interests of the zircon, zirconia and zirconium value chains, from zircon sand production, to a wide range of downstream products including zircon flour, opacifiers, refractory materials, friction materials, fused zirconias and zirconium chemicals, metal and alloys. Its membership represents some 80% of the globally-produced zircon tonnage.


For further information, please contact:

Claire Caton / media@zircon-association.org

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