Rapberry Pi powered velux windows. An old velux remote wired to a sainsmart relay board and a MCP chip. The windows are opened and closed based on the temperature of the house and the weather outside. If the heating comes on (or has been on in the last 4 hours), then the windows close.
Velux windows have sensors which close if it rains.
Each Friday is PiDay here at Adafruit! Be sure to check out our posts, tutorials and new Raspberry Pi related products. Adafruit has the largest and best selection of Raspberry Pi accessories and all the code & tutorials to get you up and running in no time!