Recently, there are a lot of buildings which have glass curtain walls from the design point of view. However, condensation often occurs on the spandrels of glass curtain walls in winter. The aim of this study is to establish measures to prevent condensation on the spandrels of glass curtain walls in commercial buildings.
The authors' previous study shows the basic concepts to prevent condensation by conducting full-scale experiments for glass curtain walls (T. Gondo, 2011).
However, in some cases there are differences between experiments and actual conditions in real buildings for example because of the influences of moisture evaporated from the calcium silicate board with high water content in the construction phase and the pressure difference between interior and exterior that occurs due to the temperature difference in winter.
In this study, case studies are conducted using simulations to clarity the countermeasures to prevent condensation on the spandrels of glass curtain walls both in the construction and operational phases. The results of the study are summarized as follows.
The conclusions from 1) to 4) are related to the operational phase and those from 5) to 9) are related to the construction phase.
1) In the standard condition, condensation occurs on the spandrels of glass curtain walls regardless of orientation and floor height. Especially, the amount of condensation is a lot for the cases for the north and with middle and high floor heights.
2) It is possible to reduce the amount of condensation by increasing the airtightness of the board, e.g., by installing joint gaskets and sealing tapes in the spandrels. However, condensation occurs on the glass of the spandrels due to the influence of moisture desorbed from and transmitted through the calcium silicate board.
3) It is possible to prevent condensation on the spandrel glass by increasing the airtightness by gaskets and exhausting the moisture from the calcium silicate board by the installation of 4 ventilation openings of 6mm x 60mm at both the upper and lower parts.
4) The installation of double glazing for the spandrel glass almost prevents condensation. However, condensation can still occur for the cases for the north and with high floor height.
5) In the cases under construction where the gaskets are installed for the board of the spandrel, condensation temporarily occurs due to the influence of moisture desorbed from the calcium silicate board regardless of orientation and floor height.
6) The amount of condensation tends to be large for the orientations where sunlight hits the board because the amount of desorbed moisture increases due to the heat of sunlight. In contrast, the amount of condensation is small for the north although condensation is generated for a long period.
7) It is possible to prevent condensation on the spandrel glass by exhausting the moisture from the calcium silicate board by the installation of 4 ventilation openings at both the upper and lower parts. The installation of the aluminum board, the calcium silicate board with low water content and double glazing are also effective.
8) The amount of condensation of the spandrel glasses is related to the insulation material behind the calcium silicate board and the paint color of the board.
9) Since condensation on the spandrel glass under construction is often temporary, it can be a countermeasure to wait until condensation disappears.
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