Environmental Sensors at House Arkko

In 2009 we constructed an environmental sensor network that is designed to monitor the conditions and the healt of the building, and to provide information about outside weather conditions. The system runs on top of our Ethernet Category 6 cable plant. Most of the sensors are so small that its hard to see whether the Ethernet port in the wall has a sensor in it. There are currently about 60 active sensors.

The main features of the system are:

• Real-time monitoring of the temperature and humidity in various rooms and inside equipment. A graphical display overlayd on the floor plans shows the current situation.

• History graphs for each collected variable.

• Jabber alarms for exceptional conditions, e.g., sudden drop of temperature in a room with a door outside indicates that the door has been opened.


• Other services include a toaster on message, humidity alarm, fire alarm, laundry dry message, misconfigured ventilation system alarm, and so on.


• Facebook application to monitor the outside weather situation.

The system itself is based on sensors that employ the OneWire protocol. Most of the programming and devices are made by ourselves, but there are some commercial components as well:

• OneWire temperature sensors, built from DS18S20 chips and Ethernet plugs.


• OneWire temperature/humidity sensors from AAG Electronica.


• OneWire wind sensors from AAG Electronica (not installed yet).


• OneWire temperature/humidity/solar sensors from Hobby Boards.


• Two 30-port OneWire hubs, constructed from 6-port hubs from Hobby Boards.


• Linux based server running in our communications room.


• Our own software for initializing, monitoring, and reporting/alarming sensor network status.


• OWFS open source software for communicating with the sensor network.


• FREETALK open source software for jabber connections.


• GNUPLOT open source software for graphics.

You can read more about the entire network design rationale here.

Created September 8th, 2009.
Last modified January 26th, 2010 by Jari Arkko

There have been visitors since September 8th, 2009.