Some homes have been built in stages over several years, and with a mix match of architecture, and central climate control. This will cause certain areas of the house to be too cold or hot to inhabit when extreme weather comes to your location. This means that you will need to append alternative heating and cooling appliances to those areas for comfort levels to even out with the rest of house.
Install electric ceiling heaters in those locations will even out temperature situation, and let whomever is working or sleeping in the room share the same atmosphere as the rest of the household.
You may have added a bedroom on for an elderly family member like your mom, or mother-in-law so they could move in with your spouse, and kids in her golden years.
The problem with add on structures or rooms is that the technology, and materials change quite rapidly in the home improvement business, and there will be issues not only with temperature ranges, but with electrical issues, insulation, carpet matching, and more.
These additions should be done with a certified architect by your side so he or she can draw on their vast experience in this situation.
When you do this type of addition without plans, and do not know where the caveats will be, especially when attaching it to the existing structure, it will cost more than what you paid the architect to fix the situation.
In many instances, an added on bedroom will either have to have a partial slab poured for an extension of the foundation. Many will not do this and add the room with piers instead. That is a bad idea, as one structure will always settle with the ground differently, and cause cracks.
I bet you thought this was going to be more about electric ceiling heaters didn’t you?