IAQ 2003, Presentation 19:
The Effects of Air-conditioning Systems on Dirt Deposition
Helen Spande, Stephen Hackney, Stephanie Conforti & Helen Brett
The earliest galleries in Tate Britain were built in the late nineteenth century and the building has been enlarged to its present size over the intervening years. There are now 3 major air-conditioning systems (HVAC), installed in 1979, 82, and 2001, on this one site. Many of the earlier galleries are not air-conditioned. This gives us a useful opportunity to study the effects of air-conditioning on the distribution of particulate pollution. Works of art that have unprotected surfaces, that is, those that are not varnished, glazed or possible to display in cases, are normally displayed in air-conditioned areas of the gallery. So it is important to know the extent of the benefits of this procedure. Measurements have been carried out in different galleries at Tate Britain to assess the effects of air-conditioning systems on dirt deposition. Glass microscope slides were placed in various locations and gloss measurements were used to estimate dirt deposition. Readings were taken during two different periods to maximise reliability, and some assessment was made of typical variations within a room in order to achieve consistent results. The slides were placed on the tops of paintings frames at similar heights, distances from the wall and locations within each gallery with respect to doors and circulation of visitors. Initial results indicate lower readings of dust in the air-conditioned spaces, but not as low as we had assumed in our procedures. This may be because much dirt is being generated internally or is being brought in on visitors' clothes. The method of measurement is likely to be sensitive to larger particles and may not be giving useful information about the distribution of smaller diameter particles. Smaller particles are thought to be more significant in terms of conservation cleaning processes, because they have good covering power and are more strongly attached to surfaces.
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