Hygrothermal simulations of energy-saving measures to stabilize the internal environment of an archive depot

In archives the indoor climate should be kept as constant as possible. Attention is focused primarily on the avoidance of short-term moisture and temperature fluctuations. Seasonal climate changes represent a lower risk. An air conditioning system (full climate control) is not optimal from an energy and financial point of view. Stable indoor climate conditions are mainly influenced by the heat storage capacity and the hygroscopic properties of the components, the air exchange with outside air, the humidity and heat from internal sources. Because of the interaction of all these parameters, it is often difficult to assess their impact on the indoor climate. By hygrothermal calculations the influence of design, ventilation, internal moisture sources and the inventory have been studied. The aim of this study is, to get an optimal climate with minimal technical equipment on an energy-saving way. The calculations show that it is essential to reach a low air exchange rate, a high standard of insulation, to avoid solar gains by windows and to achieve low humidity and heat loads. In addition it is substantial to avoid built-in moisture. The calculations also show that the so-called "Kölner Modell" with its extremely massive outer walls is not suited for archive depots. This is because the large quantities of archive material take over both the thermal and hygric buffering.