Environmental Monitoring & Library Collection Management

by | Nov 7, 2023 | Blog, Library Collection

Library collection management is a challenging task not only because you need to worry about the management of the actual books as a collection, but also because, unlike museums, your collection is freely available for patrons to take home. You need to make decisions about what to keep, buy, weed, and/or preserve. How is environmental monitoring supposed to affect any of these decisions? Let’s start with the idea that, at any given moment, you can be said to have three different types of collections:

  • Catalog collection: The entire list of books as you own them, the collection as you can see it on your CMS.
  • Shelved collection: What your patrons actually see on the shelves, including all the spaces left behind by books that have been borrowed by other patrons. Because the shelved collection is likely missing all the books that people want to read, it can give a person standing in the stacks the idea that your collection is out-of-date or incomplete.
  • In-use collection: The books that are out of the library because someone has borrowed them and are the best evidence of what your patrons want to read.

At first glance, this does not seem to have anything to do with environmental monitoring and preventive care for collections. However, circulation (or lack thereof) can have a big impact on degradation – and not just because of direct handling.

How is library collection management related to environmental monitoring?

As a library, your main concern is your patrons. Your collections must be relevant, interesting, useful, and available to your patrons. This means that your collection’s wellbeing is key. Books need to be solid enough to be circulated. They cannot be moldy. They cannot be falling apart or faded.

If you apply the Pareto principle to your collections and guess that 20% of your books account for 80% of your circulation, with the 20% being most likely new books that you purchased in the past two years, then you can find yourself with blocks of books on shelves that barely move at all and a few items in some spaces in between that are rarely there until they pass the 2 year mark. So what does this mean for your environment?

If you think about the environment around your collections and the ten agents of deterioration as espoused by the Canadian Conservation Institute (CCI), the movement of both people and items will affect aspects of your environment related to temperature, relative humidity, pollution, light, and even pests. These different agents will affect your collections differentially depending on how often the collections are actually present. Let’s focus on the shelved collection, as described above – in other words, the books that are actually sitting on your shelves because they have not been checked out.

How can patron behavior affect environmental parameters and preservation?

Light exposure

If you have automatic lighting systems which turn on and off based on movement detection (common in university libraries), a real-time monitoring system with light sensors will be able to tell you where patrons go the most. From our personal experience walking in libraries around the world, most lights we have seen in the stacks are fluorescent tubes – this means they do not necessarily have low UV emittance unless filters have been both applied and are regularly maintained and replaced.

Perhaps changing all your stacks light bulbs to LEDs is not feasible within your budget. However, knowing which lights go on the most will allow you to prioritize UV filtering or replacing those specific lights first. Placing UV filters will allow you to minimize fading and deterioration of your library materials.

Temperature and relative humidity

Darkness, higher temperatures and relative humidity (RH) levels will directly affect the chances of mold in your stacks. The more books you have in a space, the more they will be likely to buffer the humidity in the area, absorbing moisture when the RH is high and then releasing it when it is low. This difference will not only affect chances of mold, but it can also make materials swell or shrink – causing mechanical problems in the books.

If you add patron behavior into the mix, remember people are hot and breathe out humidity. This means that those areas where people walk around the most will likely have higher temperatures than areas which are rarely visited. Depending on how long someone stays in the stacks, this can have different effects on relative humidity. If the person is around for a short time, the temperatures will go up slightly, and the relative humidity can go down because of it. However, once the person has been there for longer, the humidity in their breath will be adding moisture, so the relative humidity will also tick up. If you have open desks and study areas close to your stacks, be aware of how often people use them – are they affecting your environmental parameters significantly?

Particulate matter

People are constantly shedding skin cells, dropping hairs, and bringing in dust in their shoes and clothes. Over time, areas where people walk around a lot are likely to accumulate much more dust than areas where they do not. Dust and dirt accumulation on your shelves and on the books themselves will attract moisture and insects. Enough dirt can attract enough moisture to create a microclimate around your books that will encourage mold growth, which can stain your books or worse, cause a full-scale infestation (and a health hazard).

Take note of where people walk the most and be sure to focus your cleaning efforts on these areas. Still, don’t forget to also clean where there are rarely people walking by! The lack of air movement in a space that is lightly dusty will also encourage mold growth.

Ensure proper air circulation around the shelves and storage areas to prevent the buildup of stagnant air. Good airflow helps regulate temperature and humidity levels, reducing the potential for mold growth and other environmental hazards. If you do not have a general HVAC system, place your dehumidifiers strategically based on your monitoring data.


Pest incidence will be tied to temperature, relative humidity and particulate matter. On top of this, be aware that visitors may also accidentally introduce insects into your collections. Visitor (or even staff) coats in the colder months are suspected to bring in moths in museums. Some visitors may even sneak in a snack in the stack (see what we did there?). Keep a regular cleaning schedule especially in areas with high visitor traffic. Don’t forget to add the dark, hidden spaces behind shelves and corners to a deep cleaning schedule that can be done at least every year, as dust and food leftovers tends to accumulate in them after long periods of time becoming a nice spot for insects to thrive.

If you don’t have one already, try to introduce an integrated pest management monitoring system in your stacks to catch early signs of infestations. Check out our IPM webinars if you’re not sure where to start.

In a library, keep an eye out for silverfish and booklice – both indicators of high humidity and mold. If you have any leather-bound volumes, watch out for dermestids like carpet beetles and anobiids (the original “bookworms”). If you would like to learn more about pests in libraries, check out the MuseumPests.net website. They have excellent images and labels so you can filter pests by the type of material they infest.

Sustainability and energy efficiency

A good environmental monitoring program can help you improve your sustainability and energy efficiency practices. Using movement-detection lights to avoid both excessive light exposure and energy use in areas where there are fewer patrons will lower your energy bill.

A good software program with reliable temperature and relative humidity graphs might even be able to forewarn you before your HVAC system fails completely, thus preventing a very expensive and potentially long-winded disaster.




Make sure your collection development policy includes some basic guidelines for environmental monitoring and preservation which are directly related and applicable to your unique situation and patron behavior.

You may set preferred levels of temperature and relative humidity in different areas and decide on which areas cleaning staff needs to focus on most.

If you use Conserv Cloud, you can integrate your pest observations into your monitoring program. Conserv’s partnership with MuseumPests.net means you can pull up their database images to help you identify your insects.

You can make decisions on UV-filters or new light bulbs based on which areas have the most transit.


As a librarian, your major concern is to serve your community. You are constantly analyzing the use of your collections to make decisions about new purchases and weeding. You might also be making decisions on rebinding volumes that get a lot of use and are harder to replace.

As you make your decisions, it really is preferable that you can make them based on factors that are important to you – circulation, normal wear and tear, relevance, content – you should not have to be forced to weed based on the fact that the book has gone moldy or has become too damaged by insects to continue.

We hope this article making connections between patron behavior, environmental monitoring and library collection management helps you think about your collections in new ways! If you want to learn more about how to start a real-time, wireless environmental monitoring, feel free to schedule a chat with us.

If you have any questions about environmental monitoring, integrated pest management, or just want to talk about preventative conservation, please reach out to us! Don’t forget to check out our blog or join our community of collections care professionals where you can discuss hot topics, connect with your peers or even take a course to get familiar with the Conserv platform.

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