A few years back, I decided I need to build a Home Automation (HA) system for my house so that I can collect and monitor all kinds of data around the house such as temperature, humidity, power usages as well as having the ability to control lightings, and thermostats.
For years I have many different little gadgets that I placed around the house to monitor room temperatures, humidities and the power usage. However, all these sensory gadgets come with their own displays and consoles that if I need to find out what’s the current temperature in the living room or the outside temperature and humidity, I need to physically walk up to the display unit to read the data off from it. If I want to know the power usage of the house over the weekend, I need to go into the kitchen and fiddle around with the energy monitor display unit to recall the energy usage in the past few days.
I have no issue with this in the past because I only had occasional interest in those data, until one day, I received my quarterly energy bill that knocks me off my chair. OK, we had a cold winter but the energy I used went up by more than 40%! Adding to the fact that the oil prices at the time had already shot passed US$130 a barrel and heading towards US$140. That is when I decided that I need some way to maintain a history of my energy usage of my house so that I can figure out when, why and where those energy were spent on and be able to turn-off lights and appliances when not being used either remotely or automatically.
After a bit of research, I decided to build my HA system based around the Domoticz system. The main reason for this is that majority of my collection of sensory gadgets are made by Oregon Scientific. In Europe, these sensors work in the 433.92MHz ISM radio band. With a 433MHz transceiver from RFXcom, I can quickly setup my HA system to collect data from these sensors I already have. The Domoticz system is one of many home automation systems that works with the RFXcom transceiver. This transceiver also has a growing list of devices that it can decode too. I’d suggest you check out these supported devices first before making any purchase of new sensors.
I have no idea how much processing power will be needed for a HA system, I began my experimental setup of the Domoticz system on an old Raspberry Pi 1 model B board with just 256MB RAM. For a home automation system that will be running 24×7, using a low power board like a Raspberry Pi make sense. To my surprise, this system with just a single core CPU and only 256MB RAM ran rather well and very responsive.
I was very please to find that the system not just able to capture all the Oregon Scientific (OS) sensors that I have around the house, it was also able to capture the data from my OWL energy monitor too. Although my collection of the Oregon Scientific kits were purchase over many years, the system was able to capture data from both old and new sensors.
For example, I have two OS radio clocks that come with external temperature/humidity unit. I never pay much attention to these annex units because I brought them as general alarm-clock/radio for my bedside table. When the Domoticz system scans for available sensors, I was surprise it picked up those annex sensors that I have almost forgotten about! Those sensors suddenly found its purpose and became part of my home automation system sensors.
Another important task that I wanted my home automation system to do is to collect data from my Oregon Scientific Weather station system. This weather station has it’s own display unit which I need to interrogate every time I need to find out anything about the weather, which is a pain because the display unit sits on the mantel piece in the living room. With the new HA system, I can see all the weather information such as the wind speed/direction, rain gauge, outside temperature/humidity and UV index all from the system web page. This mean I can check my home environment from my smart phone anywhere in the world.I was really pleased to see the system up and running without any major obstacles, It’s very nice to be able to see all the information I needed on one page which Domoticz called Dashboard, and now I want to add more sensors to my system. I would like to monitor all the rooms in my house, and I also want to monitor the temperature of my central heating system as well as the temperature of my fridge and freezer.
Although I can purchase, more sensors from Oregon Scientific, simple temperature sensors cost £15/ea and for an extra £5, you can get sensors that can also measure the humidity. However, I can not find any sensors for my central heating system, my fridge and my freezer that will emits Oregon Scientific protocol. I could place an Oregon Scientific temperature sensor in the fridge, but I don’t think my wife will approve it, also I’m not sure if the sensor will work if place in the freezer.
Alternatively, I can modify an existing sensor unit but that isn’t an elegant solution, I wouldn’t want to solder long wires from a stock sensor unit and have that placed inside the fridge or have it mount on the pipes of my central heating system. It will look very untidy. Besides, this is not the kind of permanent fixture that I’d like to see in my house. So instead I’ll make my own custom sensors that can emit Oregon Scientific protocol. These sensors should present itself as a normal Oregon Scientific sensor to Domiticz via the RFXcom transceiver.
In my next article, I’ll discuss how I built my own low power sensors that present itself as a Oregon Scientific sensor.