The main access to the loft is via the spiral staircase between the two courts here at the Justice and Police Museum. This presented a challenge when in 2008 we were still working to stabilise the environmental conditions in the area allocated for storage of the photographic negatives. We decided to install an independent air conditioning unit to cool this area, allowing the main unit to concentrate on cooling the three museum buildings. This would also allow more control in prescribing an ideal environment (cool and dry) for the glass plate and cellulose- based negatives.
One problem remained – how best to get the hefty new air conditioning unit into the loft? The unit is 1890 mm tall, 830 mm wide and 550 mm deep, and was clearly too stocky to fit up the narrow, spiral staircase. Our only option was to investigate whether the small window, that provides access to the roof from the loft, would admit the unit.
Luckily, the unit was just smaller than the window opening. With a few millimetres to spare, a crane and small team of able bodies hoisted the unit above the roof (showing tremendous caution for the fabric of the heritage building) and slipped it into the loft space without a hitch. Here are a few photographs to illustrate the delicate operation.
Today the air conditioning unit operates within the negative cool store, providing an environment of about 18 degrees and 35 per cent relative humidity. This environment is cool enough for preservation, reducing the rate of deterioration, yet warm enough to allow us to work in the area, assessing and scanning the photographic material.
