Environmental Monitoring and Control

Working Library Environment

In the Working Library, we use small electronic sensors called ‘TinyTags’ to monitor the temperature and relative humidity (RH) at five different locations: the Third Floor; the First Floor; and all three main sections of the Basement. (There is also a sixth tag in the Basement of the Old Divinity School, which is discussed further in the Old Library Environment report.) As usual, thanks to dead batteries and the like, we do not have a complete set of data for the year, but we can nevertheless build a clear – and mildly concerning – picture.

Temperature has been fairly consistent with previous data. With the windows still open for ventilation in many places, the First Floor continues to be the coldest part of the Library, recording the lowest temperature overall this year – a pretty inhospitable 12 degrees – and lows of 15 even in August. In the same fortnight in August, the Third Floor recorded a maximum temperature of 39 degrees, so there has been considerable variation.

Thankfully, our Basement storage areas have remained relatively stable temperature-wise, but the same cannot be said for the RH. As Kathryn explains in the Old Library Environment report, readings over 60% are cause for concern. With the exception of the Closed Basement (highs of 65%), all 5 of our other monitoring sites have recorded maximum RH readings of 70% or more. The highest of these was 77% on the First Floor last October. For the main collection of modern student texts, this is obviously concerning enough, but since we hold extensive collections of older books and Special Collections material in the Basement areas, the humidity levels in the Working Library are turning into quite an urgent issue.

Caroline Ball Graduate Trainee

Environmental monitoring in the Old Library

Temperature and relative humidity are monitored continually at three locations in the Upper Library, three in the Lower Library, the Manuscripts Store, and the Reading Room. Readings can be accessed by the Library and by Tobit Curteis Associates, who have been acting as consultants since 2014 to advise on conditions in the Lower Library, where various mitigations have been trialled to reduce the effects of high humidity. It is now clear that passive and lowintervention measures are not going to be effective, and active air-handling will be required.

The graph (page 41) shows the Lower Library readings over July-August-September 2021. The bottom lines are temperature (scale on the right) and the top relative humidity (scale on the left). RH peaked at 79.6% on the north side of the building, but it remained consistently over 65% in all three locations throughout the summer. 70%+ rings serious alarm bells, but anything over 60% has the potential for mould outbreaks, particularly where mould has been experienced before. The Old Library report gives more detail on the widescale mould outbreak which followed, and the temporary air-handling solution which has been in place over the summer of 2022. Full evaluation of that system has yet to be completed.

It should be noted that the Special Collections also use a storage area in the Old Divinity School Basement, which houses significant collections of personal papers. (Initially set up as an area to receive and sort new collections before they moved to the Lower Library, this has become permanent storage by default, as there is no space to which collections can now move.) Worryingly, monitoring shows that this basement too experiences prolonged periods when RH rises above 70% and thus poses a significant risk to the material stored there. Storage space and environmental conditions are issues which the Historical Collections Committee will need to address as a matter of urgency.

Kathryn McKee Sub-Librarian and Special Collections Librarian

School of Pythagoras Environment

Environmental conditions in the Pythagoras Building have been mostly stable this year, with a small number of short-lived exceptions such as when a leak in the boiler room external to the building but serving it and others had to be repaired. In the first half of 2022, the relative humidity percentage was in the 30s to mid-40s and in the second half (to date), in the mid40s to mid-50s. Apart from a few days in June, the temperature was within the recommended parameters of 18-20 degrees, sometimes rising to 21 or on one occasion 22 degrees in the Upper Strong Room. At the time of writing the temperature in the Upper Strong Room is 17 degrees. There have been no significant issues with insects: some silverfish were found in traps in March but are otherwise less prevalent than last year, and a discovery of what may have been booklice was made in a trap set on steps leading into a storage area but none were found in the storage area and there has been no recurrence. A trap on the same set of steps was found one morning to have been half eaten by a mouse which almost certainly came in under the nearby external door, but the mouse was not found and presumably went out the way it came in.

Lynsey Darby College Archivist