Planning Shifts of Collections:

Calculations


Determine final amount of growth space per shelf when shift is done:

  1. Count new shelves being added to the collection.
  2. Multiply them by 35" (assuming each shelf is 35" long)
  3. Add the total number of current shelves to the number of newly added shelves for your final total # shelves.
  4. Add the total newly added growth space inches to the total current inches growth space available.
  5. Divide your grand total inches of growth space by the final total # of shelves. This tells you the average number of inches of growth space to leave per shelf.
  6. Double check yourself by doing it another way: there are several ways to do it. Divide your total inches of books by your grand total number shelves, and subtract that number from 35" (length of shelf).

Example:

Given:

  1. Count new shelves being added to the collection.
    50

  2. Multiply them by 35" (assuming each shelf is 35" long)
    50 x 35 = 1,7500 new inches being added to my library

  3. Add the total number of current shelves to the number of newly added shelves for your final total # shelves.
    100 current shelves plus 50 new shelves = 150 total shelves.

  4. Add the total newly added growth space inches to the total current inches growth space available.
    1750 new inches plus 100 old inches of growth space is 1850" total growth space that will be available

  5. Divide your grand total inches of growth space by the final total # of shelves. This tells you the average number of inches of growth space to leave per shelf.
    1850 divided by 150 shelves = 12.3" growth space / shelf

  6. .Double check yourself by doing it another way: there are several ways to do it. Divide your total inches of books by your grand total number shelves, and subtract that number from 35" (length of shelf).
    • 150 shelves x 35" = 5250 total inches available
    • 5250 - 3400" of books = 1850 " growth space
    • 3400" books / 150 shelves = 22.66 inches of books per shelf
    • 22.6 inches of books + 12.3 inches of space = 34.9 " long shelf.
    Yup, it works!


Now you know how many inches of growth space you need to leave per shelf in your completed library. You may choose to leave more space in faster-growing areas and less space in slower-growing areas.

On these web pages, we're leaving the same # inches of growth space per shelf, library wide.

When you're crunching numbers, don't let the calculator or the spreadsheet convince you against your better judgement. If you have a gut feeling that something is wrong, punch the numbers around until they feel better to you. Try to draw pictures in your head of what you're doing so you have an idea of where you'll end up, and if the numbers are in that neighborhood, you know you're on the right track. Double check your answers by doing the math a different way.

Re-doing a shift on paper is a million times easier than re-doing it in real life.




Transfer data from your measuring sheets to a spreadsheet:

Floor: Range Beg. Call# End. Call# # sections hatch marks of empty space # shelves inches growth space total inches available inches of books total inches needed - final total sf sections needed - final running total sections needed
a b c d e f g h i j k l
1 1:1 A AP2.N7G43 11 8 148            
2 1:2 AP2.N7G45 AP2.P4 v.11 11 11 150            
3 1:3 AP2.P4 v.12 AP2.S3T99 12 8 165            
4 Totals 34 27 463            








Formulas for the spreadsheet:

Floor: Range Beg. Call# End. Call# # sections hatch marks of empty space # shelves inches growth space total inches available inches of books total inches needed - final total sf sections needed - final running total sections needed
a b c d e f g h i j k l
1             e1 x 35
see:(1)		 f1 x 35
see:(2)		 h1 - g1 (i1/20)x35
see:(3)		 (j1/35) / 6.5
see:(4)		  
2                       k2+k1
see (5)
3                        
4 Totals sum of
d		 sum of
e		 sum of
f		 sum of
g		 sum of
h		 sum of
i		 sum of
j		 sum of
k		 sum of
l

(1): for measuring strings that are 35" long. If you use a 36" string, multiply by 36.

(2): for shelves that average 35" each.

(3): to find out how many inches you'll need for the books on this range, you'll have to have decided how much growth space per shelf you plan to leave.

(4): Look at your measuring sheets and the actual call number area to get an idea of the average number of shelves per section:

So, remember that number (the average number of shelves per single faced sections); you'll need it in a second.

Now, divide your total inches needed by 35 (h/35) to find out how many shelves you'll need for this area. Then divide the number of shelves that you need by your ave # shelves/sf section: (ex: 6.5): (h/35) / 6.5. That should tell you how many single-faced sections you need.       *.

We're using sf shelving because the next step is to do a "paper shift": color in sf sections on maps so we know exactly where a mini-shift begins and ends.

(5): Just so you know what your grand total sections are for this shift area, add the number of sections needed up as you go along. I can't quite recall why this number is useful to us, but I found it on my spread sheet so I included it for you.




Next:
Do a Paper Shift





* 991122: Thanks to Diane Brodson of Arlington Heights Memorial Library for catching a typo/thinko in this formula. Previous to today the formula had read (h/35) * 6.5 which is clearly wrong. Got to divide by the average number of shelves per single-faced section, not multiply by them! Well, our shifts worked and our spreadsheets worked, so we must have done it right and I just typed/thought it wrong when I was writing up how we did it. Thanks again, Diane, and aplogies to anybody who got confused.


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Page created by sstevens@darkwing.uoregon.edu
Last substantive update: 970506