Air Exchange Rate and Internal Air Flows in a Naturally Ventilated Museum Building

Abstract

A controlled indoor environment is crucial to the preservation of valuable historical artefacts in museums, but is influenced by many factors such as building properties, exhibit design, number of visitors, outdoor conditions etc. This study aims to monitor the local air exchange rates (AERs) and internal air flows in the Viking Ship Museum, Oslo, Norway during different outdoor conditions and is part of a project to create a new museum for the ships. Homogeneous emission tracer techniques (with tracer A) were used to monitor the local mean age of air (from which the local AER can be estimated). The internal air flows from a building zone were monitored by loading that zone with another tracer (B). The building outline is in the shape of a cross with four wings emanating from a central tower and thus naturally creates five zones to investigate. Three measurement periods were conducted with outdoor conditions ranging from winter to late summer. During winter conditions the average hourly air exchange rate (ACH) for the museum is fairly low (0.05 h-1), but during summer conditions it rises fourfold (0.2 h-1). During the summer, windows and doors may be kept open and the number of visitors peaks. The internal flows are very large, as indicated by very similar patterns of the sampler loads for both A and B tracers in relation to the twenty sampling positions.