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Atrium Skylights Practice in Canada: A Survey on Thermal and Daylight Design Choices
Anca D. Galasiu and Morad R. Atif
Indoor Environment Program, Institute for Research in Construction National Research Council Canada Ottawa, Ontario, Canada K1A 0R6
Abstract
There is a deliberate choice of atrium skylights that have a tremendous impact on the daylighting and thermal performance of atria. A survey was conducted to determine the common thermal and light transmittance characteristics of today?s most frequently built atrium skylights, and to define the designers? rationale in selecting this type of systems. The work is part of a research project aimed at investigating the energy costs and indoor environment of Canadian atrium buildings.
A sample of Canadian atrium designers were asked to provide information about atrium projects they were recently involved in, and their needs with respect to research deliverables in this field. Requested information included the type of atrium glazing systems most commonly used in Canadian climates; the most frequently used glazing type; the relevance of daylighting in selecting the atrium glazing; and the rationale used in selecting the atrium skylight. Data about the range of commonly specified glass shading coefficients, visible transmittance coefficients, and heat transfer coefficients was gathered and analyzed.
Results of this informal survey suggest that thermal and daylighting performance are not always a priority when it comes to selecting an atrium skylight. Regardless of climatic conditions, the most commonly specified type of glazing system was double-glazing. Most designers did not identify daylighting as an important factor in the design process, and ?aesthetics? was often mentioned as the main rationale for selecting a certain type of glass and glazing system for the atrium skylight. Nevertheless, ?daylighting? contributes greatly to the aesthetics of the atrium space. The range of Solar Heat Gain Coefficients (SHGC), Light Transmittance and Heat Transfer (U-value) Coefficients being used is large, and the survey indicates no link between the magnitude of these coefficients and the climatic conditions at the location of the building.
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