Lighting technology has improved to the point where traditional filament lamps are now the most inefficient source of lighting and can be readily replaced by newer generation compact fluorescent and LED types.
Natural lighting is a much underused resource. Even in full daylight many people keep their lights burning bright. In reality, this is mostly unnecessary in terms of required levels of illumination.
There are many new and innovative products such as the light pipe that permit areas that lack direct access to sunlight to benefit from natural lighting.