i did not take the cost of reduced meaintenance in account , the reduced production cost / transport cost as a result of the longer lifespan of led.
Also the heating argument is only valid if the house is electric heated; if its heated by another source it will be cheaper then electric and as a result the few watt of heat not produced by the light will be cheaper.
Also i personally prefer to sleep in the dark so switch off lighting in my bedroom ect.
For people who are to lazy to switch light on and off there are the sensors that can do that for them and they are also getting far cheaper so that could be an aditional saving.
Since led works on direct current it becomes far more practical to have a solar panel/ storage battery setup to take care fo the ligths of a building.
Its true led ligths will "not save the earth" all by themselfs but only narrow minded people think there is a single silver bullit for all problems combined..