Nanogel® Transparent Aerogel Daylighting Panels Successful in First European Installation

EMPA tests and other research measuring the first European installation of Nanogel® translucent aerogel daylighting panels in a school sports hall in Buchwiesen, Zurich confirmed the data initially estimated by architect Arnold Amsler. The sports hall installation demonstrates even light distribution with consistent brightness and ability to maintain comfortable climatic conditions in summer and winter.

Evaluation and testing at the Buchwiesen sports hall were conducted by Peter Hartmann, Prof. Dr. Technical University (ETH) Zurich and supported by summer comfort measurements by the Department of Building Physics of the EMPA.

Scobatherm® Polyester translucent building elements incorporating Nanogel hydrophobic silica aerogel – manufactured exclusively by Cabot Corporation – were produced by Swiss building material company Scobalit and installed in 1000m² of roofing and 350m² of north-facing facade of the sports hall. Uniformly diffused light was a key requirement for the school building project and Amsler was impressed with the potential of the Scobatherm building elements to maximise the advantages of daylight. Zurich officials were also impressed by the thermal insulation benefits of Scobatherm for the potential energy and cost savings.

The planning documents for the hall specified a value of 0.03-0.05, or 3-5%, for the hall’s daylight quotient parameter. This is usually a difficult specification to achieve on a longitudinal elevation in a sports hall with normal fenestration. Although the occupied area of the Buchwiesen sports hall was located below ground level, the Nanogel filled product allowed daylight quotient to fill the hall’s complete area. In fact, the daylight quotient was exceeded in the central area of the hall.

Photographs of the building confirm the very even light distribution within the Buchwiesen sports hall. Brightness measurements plotted onto the photograph (taken on a sunny, cloudless day in March) are all in a similar range for the hall’s playing area, ceiling and rear concrete wall. This provides very favourable conditions for activities played longitudinally.

The light conditions are slightly less favourable for games played transversely because there are darker areas along the longitudinal walls. However, these light conditions are still within a comfortable range in contrast to glare.

Brightness measurements taken over a similar period at a conventionally built sports hall of a canton school at Winterthur, showed considerable variation, demonstrating the contrasts that create glare for the hall’s users.

The climate in the hall during the summer months was the area of greatest uncertainty for the Buchwiesen project. This concern was partly reduced by positioning the building so that it received as little direct sunlight as possible and when there was sunlight, it was at a low angle.

Temperature measurements were taken inside the hall during 10 days in July when it was not in use and when outside temperatures, not in direct sunlight, rose to 30-35°C. When a combination of the hall’s programmed night ventilation with open windows for about 40%of the day, the inside temperatures rose 2-4°C above outside temperatures. When the windows were left open at all times during the day, except when it was raining, the internal temperature was always below the external reading by an average of 4°C. The maximum temperature in the hall was reached at 17.00 hours, well outside normal primary school teaching hours.

The tests demonstrate that a marked improvement in the climatic conditions could be achieved in summer by optimising the ventilation. Even with peak temperatures outside of 33°C, the hall’s users would be able to stay inside for longer hours at temperatures below 26°C.

Architect Arnold Amsler says the comparison of daylight and glare between a sports hall of standard design and that built incorporating the Scobatherm building elements is strongly in favour of the Buchwiesen project, its bright atmosphere being particularly impressive. He believes further improv

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