Moisture is the number one enemy of preservation. Not only does it result in the decay of paper, parchments and photographic film, it also causes organic colours and dyes to fade. If proper measures are not taken in time, then priceless artifacts made of organic material like wood, leather, paper, natural fibre, bone and ivory could be lost forever. Also, the storage of items such as classic cars and possessions stored within self-storage facilities are also at risk from uncontrolled humidity.
Generally warm and damp conditions can increase the speed of decay, but this can double with an increase of as little as 5°C. High temperatures can cause document wax seals to soften and even result in the combustion of cellulose nitrate film. At low temperatures, organic and plastic materials become brittle making them prone to physical damage. Excess moisture can cause corrosion, rust, mildew, mould, damage to car interiors, cardboard boxes collapsing, leather book bindings cracking,degradation of photographs or documents, high costs and energy wastage.
Although heating is often used as a way to control the relative humidity (RH), this method is both ineffective and costly. Meanwhile, the energy saving when using dehumidification compared to heating is approximately 60 per cent.
Humidity, temperature, light and air-borne pollutants all contribute to the deterioration of archival materials. Storage conditions that are too damp can encourage insect pest activity and the growth of mould, while conditions that are too dry can cause archival materials to become brittle. If the documents are subjected to sudden fluctuations in humidity, then the rapid loss and absorption of moisture can cause microscopic structural damage that will contribute to the overall deterioration of the material. The temperature can also affect deterioration because chemical reactions are faster in warmer conditions.
But it does not just have to be historical archives that are at risk of being damaged because of poor storage management. Important legal documents and financial records also need to be retained for a period by law here in the UK.
Maintaining the relative humidity at a correct and stable level by implementing correctly dimensioned dehumidification solutions is the first step in safeguarding archives and storage areas. Often these solutions can be based on refrigerant or desiccant dehumidifiers that have been designed to protect archives, galleries and museum buildings and, of course, the treasured items on display.
These high-performance dehumidification and ventilation systems both regulate and then control temperature, humidity and air quality. Recirculating the air and physically removing moisture from it, they also alleviate the need to continuously reheat incoming air as well.
If the dehumidification solution has integrated reversible heat pumps, the units convert energy taken out of the room as moisture to provide useful heat to warm the room, accelerating the drying process.