An evaluation of daylight distribution as an initial preventive conservation measure at two Smithsonian Institution Museums, Washington DC, USA

This paper presents the results of a light levels survey conducted at the Donald W. Reynolds Center for American Art and Portraiture in Washington DC. The museum space is shared by the National Portrait Gallery and the Smithsonian American Art Museum. After six years of extensive renovations, the building reopened to the public in July 1, 2006. The structure was not originally designed to house a museum collection since it contains numerous openings such as windows, doors and skylights, which provide a path for natural radiation to enter the building and come in contact with the artworks. From a preventive conservation standpoint, this is an important problem since sensitive works of art in the collection may be subjected to damage caused by light exposure. Environmental data loggers installed throughout the museum were programmed to take successive measurements every 10 min for 24 h a day, 7 days a week and 52 weeks a year. This light levels assessment started in November 1, 2007 and finished in October 31, 2008. This study presents a new method for determining natural radiation exposures registered in exhibition spaces that rely on both electric lighting and natural lighting, considering the growing trend of using daylight illumination in museums.