Generally, use hyphens when a pair of words are used adjectivally, but only when the meaning is ambiguous otherwise. The library brings a lot to the table and I am sure you will at some point in your projects find it very useful. Take your pick from leather school shoes, more casual black plimsolls or even a pair of durable school boots to see out the year.
It is hugely appreciated if you can mention where you found me from ie: google search, orangutan foundation, article, advertising. And as someone who genuinely enjoys exercise and feels great after a run (and on the whole avoids custard creams and caffeine all day) I just don't understand people that would choose to live without that endorphin rush and sense of well being that exercise brings. This brings infra red motion and hatch opening intruder detection, water in bilge, and engine temperature warning for unauthorised engine use.