Roller shutters can have a surprisingly big impact on greenhouse gas emissions and energy bills. The additional layer offered by the roller shutter acts as a great form of thermal insulation, although certain styles are of course more effective than others. For example, thick galvanised steel will have a significantly greater impact on heat retention than perforated aluminium, but either way the difference to your energy bill will be noticeable.
It applies the other way round too. In the summer, the roller shutter keeps out heat when it is closed and also prevents the thermal magnifying effect of glass on the inside. For this reason it can also help to reduce your electricity bills in the summer as you are less likely to require air conditioning.