One of the big energy hogs in our house is our clunky old second fridge in the garage. I measured its energy consumption with the [MS6115 power meter](http://green-change.com/2008/11/27/ms6115-mains-power-meter-review/), and it uses a whopping 2.5 kWh/day!
Many Aussie houses have one of these beasts, which is a big reason why the NSW State Government is now offering money to people to [hand them in for recycling](http://green-change.com/2009/03/26/fridge-buyback-scheme-come-to-the-illawarra/).
Simply getting rid of the fridge is difficult, though. We have three young children, and so go through a lot of milk, yoghurt, and juice (and, truth be told, wine!). If we turned off the second fridge and only used our main one, we’d have to shop for milk and juice every couple of days. The second fridge gives us the space to store a weeks’ worth at a time.
A while ago I read in [Renew](http://www.ata.org.au/publications/renew), the magazine of the Australian Alternative Technology Association, a story about [hacking a chest freezer to operate as a chest fridge](http://mtbest.net/chest_fridge.pdf?PHPSESSID=906149616069103a408b942ea2e93110). The author has posted about [his chest fridge](http://mtbest.net/chest_fridge.html) on his Mt Best web site.
The concept is actually very simple. You take a chest freezer, plug it into a temperature controller, and place the controller’s temperature probe inside the freezer. The device then just turns the freezer on and off at the wall depending upon the temperature inside it. If you set it to about 3 degrees C, it works as a fridge.
An alternative approach is to simply swap the freezer’s thermostat for a fridge one. Although technically reversible, this is a little more of a permanent hack. A very good article about it was recently published on the [Aussies Living Simply](http://aussieslivingsimply.com.au/articles/fridge.pdf) web site.
Why would you want to do that?
Because chest freezers have great insulation (2-3 times thicker than a fridge) and open from the top (so you don’t lose all the cold air when opening them), this makes for an incredibly efficient fridge. Various people around the net are claiming they use just 0.1 to 0.3 kWh/day. That’s 1/10th of what my clunker of a fridge uses!
This simple idea has played on my mind for over a year now. So this weekend I began my own Chest Fridge Conversion Project.
First step was to obtain the freezer. I’ve been keeping an eye on eBay, newspaper classifieds, notice boards, etc for a while now. Finally, I discovered a guy around the corner from me selling a Westinghouse 210L chest freezer. Perfect! Twenty minutes and $90 later, I had a working chest freezer.
The [thermostat used and sold by Mt Best](http://mtbest.net/freezer-to-fridge-thermostat.html) is a little pricey for my project at $150, although it looks very good. I found an [alternative temperature controller](http://mashmaster.com.au/p/365439/fridgemate-mkii-digital-temperature-controller-kit.html) that works the same way at a home brew supply shop for just $50. Home brewing people use these with old fridges to maintain a constant temperature for optimum fermentation – exactly what I want to do (hopefully without the fermentation, though).
So I’ve ordered the FridgeMate Mk II digital temperature controller, and am eagerly awaiting its delivery. Stay tuned for an update!