Heavy demands are made today on the indoor climate in storerooms of museums and archives. These demands have resulted in increasingly advanced air-conditioning plants with high initial costs and on-going operating expenses. The control and maintenance of the installations are so difficult that often it is impossible to maintain the specified indoor climate. A Swedish-Danish research and development collaboration was established in order to map the thermal values and humidity of the outdoor climate, the building, the indoor climate, and the storage areas. The state archives of Schleswig-Holstein are stored in unventilated, well-insulated rooms that are heated to maintain an almost constant relative humidity, buffered by the archives themselves. -- CAL