On my dream home...
Someday I'm going to live in a house that not only has amazing insulation, but also has a smart passive central heating and cooling system. This house will have duct work like you'd find in a central air or forced air system, but it will also have a brain and eyes, and it will know how to use the internet. You see, it will have a temperature sensor outside the house, one (or more) inside the house, and a computer that can go on the internet to get the weather forecasts. I will give it a set of temperature parameters, a comfort/target zone and then allowed extremes. It will intelligently use external air to heat and cool the house. For example, in the summer it will blow in cold air at night, but only as much as is needed to keep the house in the comfort range the next day given the forecast. In the fall, like now, it would blow in warm air during the heat of the day (but not too much!) and then stop blowing in air when the outside air temperature drops below the inside air temperature. It could do all this with fans and only turn on the heat or AC when it was really necessary, and while I approximate this by opening the windows and using fans right now, I don't always notice when they need to be opened or closed in a particularly timely way. Actually, I'm really bad at noticing. I think this could greatly reduce my energy consumption and while improving my comfort.