In colder countries it reduces the energy bill significantly. The cost of lightning is reduced as the glass helps with better natural illumination and also the heating due to green house effect reduces the need for extra heating. These are essentially the same reasons that lead to higher energy consumption in the hotter countries like India. As the sunlight is very hot the curtains and blinds remain perpetually drawn resulting in a need for extra illumination and the green house effect increases the need for higher cooling. The Air Conditioning systems feel inadequate most of the time. It is like living inside a large inefficient Solar Cooker.
