Some embodiments provide a program that receives a first set of data and a first greenhouse gas emission value. The program stores, in a cache, the first set of data and the first greenhouse gas emission value. The program receives a second set of data and a second greenhouse gas emission value. The program stores, in the cache, the second set of data and the second greenhouse gas emission value. The program receives a third set of data and a third greenhouse gas emission value. The program determines one of the first and second sets of data to remove from the cache based on the first and second greenhouse gas emission values. The program replaces, in the cache, one of the first and second sets of data and the corresponding first or second greenhouse gas emission value with the third set of data and the third greenhouse gas emission value.