Choosing your lightbulbs

You usually choose a lightbulb depending on it's shape, technology and aspect. But you should normally choose your lightbulb depending on the size and type of room you want to light.
The rule is to use 15 to 20 watts per square meter in living rooms and kitchens, and 10 to 15 watts per square meter for rooms which you use less and for bedrooms.
Divide these numbers by 5 if you use ecological lightbulbs.