Hygrothermal optimisation of museum storage spaces

Abstract

Despite the large economic and ecologic costs, museum storage spaces are often equipped with extensive air conditioning, to provide the desired stable interior climate. The new "passive conditioning" paradigm aims at resolving these costs: a high-hygrothermal-inertia building with a high-hygrothermal-resistance envelope is to satisfactorily stabilise that interior climate, with no need for mechanical air conditioning hence. This paper first studies the reliability of full passive conditioning for museum storage spaces. It is shown to be an illusion, since it usually results in excessive interior humidities. Auxiliary dehumidification is thus required to provide good conservation conditions, and it is secondly investigated how the dehumidification load can be diminished. The study reveals the crucial impact of air tightness, while thermal insulation only has a minor influence. To further reduce the economic and ecologic cost of conditioning, the paper finally assesses "concentrated dehumidification": dehumidification during a part of the day only, while leaving the humidity free-running during the rest of the day. It is established that the hygric inertia of the interior air, building walls and stored objects keeps the fluctuations of the interior relative humidities to a minimum when considering adequately air tight museum storage spaces.

Internal environment in the museum building—Assessment and improvement of air exchange and its impact on energy demand for heating

“…The average number of visiting groups ranges from 15 up to 30 people. On the other hand, large air exchange can have an undesirable effect as it causes additional dehumidification of air and makes it impossible to maintain appropriate environmental conditions in storage areas [29,30].…”

Influence of Indoor Microclimate Distribution on Mould Infestation in a University Library

“…On this, it should be noted that although the ultra violet component of the light spectrum are found to be detrimental to growth of microbes [5], the same is identified [16] as one of the deteriorating factors of stored collections of books and archives. More so, the heat from sunlight increases the ambient temperature and hence inhibit the growth of some species [2,17]. Nevertheless, excessive heat intrusion into the buildings remains a contributory factor to an increase in cooling loads on HVAC systems-an energy efficiency issue.…”

Temporal humidity variations in the heritage climate of south east England

“…These damp days would fungi and mould to be more likely to grow (e.g. humidity temperature data of Polizzi et al [20]). Again the frequency is much higher in the UKCP09 projections than for the MIDAS observations at both Heathrow (diamonds) and Gatwick (squares).…”

“…An example would be estimation of the amount water removal required each day for dehumidification. Janssen and Christensen [20] explored the optimisation of the thermo-hygrometric climate of museums and determined the large amount of water to be removed from the interior to maintain 50% relative humidity. This removal was typically required in summer where cooling imposed increases in humidity.…”