The State Hermitage Museum, St Petersburg

Case study: daylighting

Stephen Cannon-Brookes, 17.01.2011
Stephen Cannon-Brookes explains how climate-based daylight modelling helped to facilitate the maximum use of daylight in the State Hermitage Museum in St Petersburg
STATE HERMITAGE MUSEUM, ST PETERSBURG

The redevelopment of the east wing of the General Staff Building at the State Hermitage Museum in St Petersburg provided an opportunity to test out climate-based daylight modelling (CBDM) within the parameters widely experienced in museums with daylit interiors. CBDM is a computer-based analysis of daylight in interiors that uses realistic sky and sun conditions to accurately simulate the amount and distribution of light. Click here to find out more about this technique

The museum requested maximum use of daylight in the galleries, the avoidance of active systems of control and adopted maximum dosages for the exposure to both daylight and electric light on vertical hanging surfaces.

CBDM was employed to analyse dosage levels in existing sidelit interiors, which will be used for displaying paintings and decorative art objects and as a predictive design tool for new toplit galleries (see below) earmarked for the Impressionist collections.

Using CBDM on a three-dimensional model of a test room, a prediction of annual dosage was derived for the walls and floor. Tests were made of annual daylight dosages for normal opening hours, assuming blackout at other times. The findings showed that there was, as expected, a wide variation of dosage across surfaces and also how much this is influenced by sunlight.

Not surprisingly, just short periods of sunlight falling on a specific area can easily exceed the recommended maximum annual dosage. However, the location of sunlight penetration is predictable with respect to time of day and year, and this allows for relatively unsophisticated control using diffusing shades of the type commonly used in the Hermitage Museum. Outside the “risk hours”, the windows can be left unobstructed and the dosage pattern showed that minimal further intervention was required.

This finding supports a rather different attitude than that widely promoted for daylit interiors with light-sensitive contents. This is because it allows the integration of objects with the performance characteristics of the building and for selection of the preferred level of intervention to control daylight exposure, the default being passive low-risk solutions.


MODELLING NEW TOPLIGHT GALLERIES

As an historic building within a tightly policed conservation area, there were only limited opportunities for the Hermitage Museum and its architects to realise a series of toplit galleries for its Impressionist collection. The daylight design evolved from these limitations into a series of pyramidal ceilings and relatively small openings, which precluded the need for active control of incident sunlight. And during the winter, it provides a degree of “liveliness” in the limited daylight present.

CBDM was used to tune the basic design of the galleries to show that dosage levels on walls could be relatively even, despite the sunlight tending to create a high degree of asymmetry. This was achieved by relying on sunlight being reflected and diffused by the pyramidal ceilings, most of which are broken into two vertical zones to avoid sunlight penetrating close to the wall and thus becoming distracting.

The technique also allowed the evaluation and inclusion of a passive redistribution material in the glazing of the rooflights (Serraglaze), which was positioned to reflect a large proportion of high-angle summer sunlight from the roof while admitting low-angle winter sunlight.

The net result was a gallery design requiring no active intervention to control sunlight and only a blackout blind to avoid exposure outside visiting hours.

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