Here is a recipe for an efficient glass cleaner that will leave your windows sparkling.
To make 3 pints/2 liters
4 floz/115ml rubbing alcohol
4 floz/115ml household ammonia
3 pints/1.75litres warm water
Pour the alcohol and ammonia into a bucket, add the water and mix well. To use, transfer to a spray bottle and spray the glass with it. Allow it to sit for 30 seconds and then wipe off with newspaper.