Insulin not in use (ie a pen or a vial that has been opened and used) should be kept in the fridge as insulin only lasts for about a month out of the fridge.
Insulin that is in use should not be kept in the fridge and should be disposed of after about a month/28 days.
@not-so-lucky have you tried reading the patient information leaflet with storage instructions on it that comes with your novorapid? You might want to check if you are actually following the guidance set out in that.
@spaceman flipping heck, are you recommending that instead of keeping insulin in the fridge, as the manufacturers recommend, people keep it in two locked boxes near a wall? What is the guarantee the locked boxed aren't just going to be at room temperature, so the insulin will only last in the double locked boxes for 28 days? What danger is there to children in having insulin in the fridge? Unless you also keep your needles in the fridge what are the going to do with the chilled insulin? Drink it? Apart from probably not tasting very nice drinking it won't actually do them any harm because the stomach acids just destroy the insulin, that's why we have to inject it. Unless you're also locking away your bleach and your beer, locking your insulin away seems a little extreme.