(See also part 2 at http://cspgs.blogspot.com/2014/02/other-areas-library-expansion-plans_17.html )
In 2007 Sunnyvale proposed a Library Bond measure for $100M for the tear down of the existing library and construction of a new library of 100K sq. ft. - a cost of $1,000 per sq. ft.. There was no money set aside over previous years for this proposed expansion. There were no pictures, architectural drawings, mock-ups, or plans for the proposed library.
Not every city does it that way. Here are what some other cities and counties have done: Click on a slide/photo to get a greatly enlarged view.
The Chapel Hill, NC public library more than doubled in size (27K to 62K sq. ft.) at roughly $500/sq. ft. The plans were laid out - and built as described. Finished April, 2013.
A full set here including floor plans of both floors:
Completed view exterior
Completed view interior
See images at: http://chapelhillpubliclibrary.org/txp/index.php?id=854
For a fantastic interactive panorama view of the Chapel Hill, NC new library, enabling you to walk through it, see here (must see):
Here's another - a small (5,000 sq. ft.) library with a 50% increase to 7,790 sq. ft. at $200/sq. ft., construction started November 2013. C.f., http://haworth.bccls.org/images/haworthpowerpoint-2.pdf
In 2007 Sunnyvale residents were voting for a bond measure purely on faith that the proposed library would be what they wanted. Without any opposition, it received 59% of the vote, failing to garner the California constitution's mandated 2/3 majority for a tax increase.
The Kent County, Michigan library system created several floor plans and drawings as a natural part of the planning process. Doing this does not guarantee a successful vote for the expansion, but NOT doing it is a recipe for failure.
For more plans see: http://www.kdl.org/kdl/pdf/GrandvilleExpansionPlan.pdf
The Sunnyvale "Library of the Future" study often referred in support of the 2007 bond measure had no drawings, no floor plans, nothing at all to indicate what the library would look like and what it would include. There has been no plan since then to go to the voters again with a more clearly articulated library and bond plan. Too bad. With proper preparation, a well designed building expansion could win.
There are quite a number of libraries which expand and modernize around the country without tearing down what exists. Here's one county library in Wyoming. Even though money was set aside over 30 years ago, detailed plans were made public so residents could form an opinion.
Although we can assume everyone involved in the Sunnyvale proposal was honest and sincere, some people are likely to be a bit skeptical without more detail of what was going to be built than was provided (i.e., close to zero). In trying to get money for a library expansion, (which Deborah and I both support) it is important to convey as much information as necessary to convince people to raise their own taxes.