The first sensor node consists of a WeatherDuino transmitter and an Air Quality Monitor housed in a weatherproof box fixed to the side of the house. A mains adapter in the room directly below the Node provides 12 volts DC to the TX board and the AQM. A variable DC-DC converter provides approximately 10 volts to a fan which draws fresh air from outside via a fine mesh filter. A similar filter covers the exhaust port of the weatherproof housing.