So, this is hardly even an engineering question, but here it goes anyway. I'm off from college; my parents are at work and my brother is at school. I'm the only one in a 4 person house with central air, and I'm cold. So I turn up the heat. But I'm the only one home, and I'm just in my bedroom. I don't need the living room, bathrooms and other bedrooms heated, just my bedroom. So I'm wasting a ton of heat just so that one relatively small room is a few degrees warmer. So has anyone ever engineered a way to heat only specific rooms with central air? It seems like it'd be very easy to just make switches for each air duct to control whether they stayed open or were shut off. This way, in situations like mine, I wouldn't have to burn enough fuel to raise the whole houses temperature so that I can be warmer, I'd only have to burn a fraction of that. It could also be useful for houses where certain rooms are perpetually colder or warmer than others. It seems, from here, that it wouldn't be hard to automate the system, have a thermostat in each room, and have air ducts that let an adjustable amount of air in, so that when the heater is running, everyone can control exactly how warm their room should be. Does this seem unreasonable to anyone? I feel like the technology to do this is at least half a century old, yet I'm not sure it's ever been tried. With prices for fossil fuel so high lately, it could also save people a lot of money, and make whoever started selling it some money as well.