I have a good collection of hanging calendars of 2015.Like these:
Instead of burning them for fuel or selling it for recycling, how can I use it for another purpose within my office/house?
These are some ways by which I reuse a calendar:
You can use each sheet of the calendar to dress up your wardrobe in which you keep your clothes or book racks.
You can also dress up the kitchen rack in your house, where you keep your utensils. (This will help absorb moisture and will protect the rack if it made of wood)
The best way to use it would be to wrap up old books or even textbooks and notebooks of school children. Especially if one side of the calendar sheet is blank/white , you can wrap the book with the white side up.
If you can keep them until 2026, the days will be aligned the same as they are in 2015. ie Jan 1st is a Thursday and 28 days in Feb.
EDIT : More explanation. You can use a 2015 calendar as a 2026 calendar. There are 14 different patterns of days that a year can have. leap years that start on a Monday, non leap years that start on a Monday. Leap years that start on a Tuesday, non leap years starting on Tuesday and so on. 2 variations for each day of the week. If you were to look to see what day March 23 falls on a 2015 calendar it will be a Monday. You can use the same calendar for checking what day March 23 falls on in 2026, it will be Monday again, that day cycle has come round again.
If you have children available to you, donate the calendars to the children as raw materials for art projects.
It appears that the calendars are made of paper, so that could be turned into backing, paper mache, etc. Add some glue and creativity, and your are having a good time!