New York Library Association. - The eBulletin

Facility Planning: Making Sense of the Data - Collections

Part 6 of the Facility Planning Series by Karen Watson & Robert Hubsher

“I don't profess to be profound; but I do lay claim to common sense.” ~ Emily Dickenson

Weeding collections is a subject that many librarians often find difficult to talk about, let alone do.  However, it is an essential part of effective collection management.  How do you manage your collections?  When do you let go of parts of collections?  Managing your assets is fraught with difficult decisions but it is essential when you are planning any physical changes in your library.  Take heart!  With your strategic plan as your guide, you have a road map to help you plan future collection development.

Looking at your collections as only one of the resources available to you at the library will help you to regard your collections objectively and without emotion. It may be cozy and comforting to surround yourself with books but not when overstuffed shelves are a detriment to fully meeting your users' requirements. (This is a photo of shelving in a library in New York – thank you to the librarian there for allowing me to use it)

Gathering, Documenting and Making Sense of Data about the Collections

The space required to accommodate a library's collections will account for 40% to 60% of the total area in a public library building.

Accurately representing the size of the collection is critical in determining the appropriate size of the building.

It is, however, unwise to simply assume that what you have on your shelves now is what you will need to accommodate your users’ needs. Before gathering any data about the size of the collections, the collection must be rigorously weeded.

Why waste space that can be used for other purposes by housing materials that have remained unused for years and are outdated or in poor condition? I have participated in a move that was done before weeding.  It was discouraging to know I was putting books on shelves that were soon to be removed and sold at the local book fair.

Weeding the Library’s Collections: How to take full advantage of your ILS

Your library's weeding policy should include criteria for removing materials based on use, age and condition.

Use criteria will define a standard for removing items which are underused. Reports generated by the ILS will provide information about use, particularly about materials that are most heavily used and those that are underused or not used at all. Serious consideration should be given to removing an item that has not been used in the last two or three years.  Of course all items should be considered on their own merits. For example, you may want to retain titles, even those that have not been borrowed recently by an author who is experiencing a rival of interest spurred perhaps by a new movie or television series based on one of her books.

Age criteria should be based on established standards for materials by subject. For example, 000 (computer science) should be no older than two or three years; 389 (Folklore) may be kept as long as condition permits; 540s (Chemistry) should not be older than three to five years; and 590s (Zoology) should have nothing prior to 1986.

You can also prepare reports from your ILS that list items older than the defined publications date for each subject category in your weeding policy.

Condition criteria are somewhat subjective.  Safe to say that books with missing pages, CDs or DVDs which are scratched and cannot be repaired, and materials which are water-damaged, smelly or moldy should be removed.

Gathering data about the condition of the collection requires the actual physical examination of materials to determine if they are damaged and, therefore, candidates to be withdrawn or replaced.

Information about use, age and condition of materials will help you make decisions about retention, which can reduce the size of the collections and hence reduce space needs. Although we are not addressing collection development, it is important to note that the data on heavily used materials can help you find patterns that will support decisions about the acquisition of library materials. Such patterns, in turn, affect space planning. For example, data may show that fiction materials are used more heavily than non-fiction, but that currently, the latter occupies proportionately more space than the former. Such a scenario could indicate a need to increase the space allocated for fiction and possibly reduce the space for non-fiction.

Overall, the data you collect will help you make strategic decisions about your collections and assure that the appropriate amount of space is allocated.

Collection Size Calculations

The next step; gather information about the quantity of items in your library’s collections. You will then be able to translate this information into space requirements for use by your designer.

Your ILS can generate reports that identify the number of volumes/items held by the library in each collection type. It is important to divide data by collection type if collections are shelved separately. For example, non-fiction materials are usually shelved as a single collection, however, some libraries maintain a biography collection separately; fiction is usually shelved as a single collection, but some libraries shelve at least some genres separately.

Even though the collections are shelved in a continuous run, it is common practice to separate collections and begin each in a new bay, which effects the total space requirements for your shelving. Keep in mind that different types of AV materials are also shelved separately.

Formulae that have been commonly available for years can only provide you with an approximation of the space required to house your collections and will be useful to you only during the very preliminary stages of your library building project. These formulae use data about your library’s holdings and a multiplier to calculate the space required; for example, 8 books per square foot.

However, these calculations do not take into consideration the differences in size of materials by collection type, nor the fact that some collections are shelved separately.

For example, picture books occupy much less space per volume than do adult books and even among adult books there are wide differences in the size of items; collections such as genre, large print, picture books, etc. are shelved separately occupying more space than they would if shelved as a single collection.

End unit use is becoming more popular and can help increase your shelf space and encourage browsing.  This type of display will naturally have an impact on the way your designer plans the number of square feet allocated to your stacks.

In the Library Development Guide: Making the Case for Your Building Project – there is a table to help librarians prepare a preliminary assessment of the space their library requires.  This table provides a list of components found in a library building.  In the “COLLECTIONS” portion you will find multipliers for face out display of books, reference books, periodicals, face out periodicals, paperbacks and other collection-related items. Here is a link to a Word format version of that table:

Each year new items are added to your collections, items are lost and, if you weed regularly, items are removed. You can generate reports from the ILS to determine the number of items within each of these categories. Use this data to determine the net number of items added annually (Net# = the total number added minus the number lost and weeded).

The library’s strategic plan will affect the nature of the collections. For example, your strategic plan may call for the library to develop a comprehensive business collection and may point to gaps in the collection that need to be filled. You will need to determine the number of items that will be added and factor this into the calculation of the size of your collections. For an example of an approach to evaluating your collection, see the Southern Ontario Library System (SOLS) publication, A Guide to Developing a Collection Plan (2009).  A description of this Guide and a link to the main body of the text is available at:

Anticipating changes in the size and nature of the collections over time will help to assure that future needs can be accommodated. It cannot be emphasized enough that any changes in the nature and size of the collections or the approach to how items are displayed will have an impact on the space required for the collections and the adjacent areas.

Your final calculation of the shelving needed to accommodate your collections should include a percentage of unoccupied shelf space. Unoccupied shelf space makes reshelving and adding new items easier, facilitates collection management, and improves user access. The recommended percentage for unoccupied shelf space ranges from 10% to 25% per shelf.

These days there is a great deal of conversation about the end of print.  If we are to listen to the pundits, including some librarians, it would appear that we do not have to plan for physical collections because everything will be available in digital format.  We know that digital content will continue to increase, but we want to make it very clear that print will not disappear anytime soon.  Did you know that Amazon, the number one seller of e-books, started a print publishing company in 2009?  We do not believe they started this business out of altruism but rather because their market research indicated that there is a demand for print and hence a profit to be made.

There are two methods for gathering data about collections. The first, already mentioned above, is to generate reports from the library's ILS (if a library is not automated it will be necessary to actually count the physical items in the collection).

The second method is to actually go into the stacks and measure the linear feet of materials as they are arranged on the shelves, ensuring that each collection type is measured separately. Be sure to measure the materials only and not the shelving. Keep in mind that the best time to do this is only after the weeding has been completed.

What your Architect needs from you …

An architect or design professional will use the linear feet figure for each collection to accurately determine the space required for shelving in your library space

As you communicate your needs to a design professional be aware that you are giving information to a person who thinks visually usually in color and in three dimensions. The clearer you can be about your collections’ sizes, dimensions, placement and separations the better the architect can understand you. Although measuring the collections is time-consuming, it provides invaluable information which cannot be gleaned by simply knowing the quantity of the items in the library’s collections.



Click here to read Part 5 of this series.
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Click here to read Part 3 of this series.
Click here to read Part 2 of this series.
Click here to read Part 1 of this series.