Having retrofitted thousands of homes, I have come to the conclusion that most two-storey homes are constructed upside down. In a typical two-storey home, the bedrooms are upstairs and the living areas are downstairs.

In winter, when you put on the central heating and try to warm up the living spaces, the warm air rises. This sends heat to the bedrooms and leaves the downstairs section cold. This creates an uncomfortable environment in both sections of the home. In the middle of summer, the upstairs bedrooms become superheated because they are (often) not shaded by surrounding structures (buildings or trees).

Upstairs bears the full force of the sun all day. In addition, hot air rises from within the home. Turning on air conditioning upstairs to try to cool the bedrooms, will result in the cool air sinking to the ground floor. This is because cold air is dense and heavier than warm air, so it will fall down the stairs or void. This means downstairs is cooler, but upstairs is still hot and uncomfortable. This is why when you go to bed at night in summer, it may be hot upstairs despite running air conditioning.

In addition, having a bedroom over a garage can be problematic as the garage heats up and passes the heat directly to the bedroom above. Often garage doors are metal, which conducts heat and that makes a garage a pretty hot place. More often, there is no insulation between the garage and the room above. So a bedroom over a garage can have quite a thermal issue.

This is why I think two-story homes are upside down, the bedrooms should be on the ground floor of the home and the living areas should be upstairs.